A Laboratory Manual for Students of Electrical Engineering Citation Forster, George (1926) A Laboratory Manual for Students of Electrical Engineering. Master's thesis, California Institute of Technology. doi:10.7907/W7JZ-JV04. https://resolver.caltech.edu/CaltechETD:etd-04262004-140837 Abstract No Abstract. Item Type: Thesis (Master's thesis) Subject Keywords: Physics ; Electrical Engineering Degree Grantor: California Institute of Technology Division: Physics, Mathematics and Astronomy Major Option: Physics Minor Option: Electrical Engineering Thesis Availability: Public (worldwide access) Research Advisor(s): Unknown, Unknown Thesis Committee: Unknown, Unknown Defense Date: 26 May 1926 Record Number: CaltechETD:etd-04262004-140837 Persistent URL: https://resolver.caltech.edu/CaltechETD:etd-04262004-140837 DOI: 10.7907/W7JZ-JV04 Default Usage Policy: No commercial reproduction, distribution, display or performance rights in this work are provided. ID Code: 1507 Collection: CaltechTHESIS Deposited By: Imported from ETD-db Deposited On: 29 Apr 2004 Last Modified: 03 Oct 2019 23:08 Thesis Files Preview PDF (Forster_g_1926.pdf) - Final Version See Usage Policy. 14MB Repository Staff Only: item control page

A LABORATORY MANUAL FOR Ae au STUDENTS OF ELECTRICAL BXGINTERING - O = George Forster e requirsnents for the degree tor of Science, at tne ietituis of Technology, May 26, 1025. “——“Tavee OC Eapt F700 1 Expt *2 0 Cmermiam 406, SDC —EXpEwSI OS, Open this sev when takin S Sht fid. ressta fid, vesig- tance ments. Expt *7 OC. ' Take Serfid. tes. while gen. ts loaded. \ FL Loan ReHEO. *9D.C,100C. HOw, LINE Sw 3 Oc, Disconnect VM. before opening ine sw. / 4 i Vv +BUS. + -BuUS. ~- j LINE sw + + evs ; 4. - t aus. ! LINE Sw. \ Loan : c RHEO. i i LoaD i Rife 1 Expt#Z A.C. wan Rrtcs. Loap : Heo. | QYNAMOMETER BOARD. i Qo NOY CLosE NORE Ke THAN ONE Switch | | lev. & | ° | | | txpi Sac, t POWER cagror INDICATOR. GENERATOR SYN. MOTOR ran FLD. (RoTor) llevac. Nov pc. DO NOT CLOSE DYNAPMOME: BOARD, Expt "4A, 6AL. THAN ONE SwitcH. - Expt.®8AC, 9AC. __ | TER | Lou" _ J HOV AC. Pri —" cal | nov 1 C. Ae tc. a e oe! VAM. sw. Te c @ ovo. ov oc ry TOWRM. TO WM DYNWAMOME TER SERIES COM, SEMIES COU BOARD TOWM. POT TowM. for COILs. cos. A ‘ovne. Expt #10A.C, IAC. Expt. *12AC ' Ret. . 3 ; f i —l a oor ALS cB end ’ > TO? mee. he an 2¢ Ciegurr ! | eng | pas L tL (Gace 5 : v i | v 1 i TO WM Pot. i con Towm - wm, Tow S seecon, SERCO POT 4 : | | cous. LIne i ry \ Lue ; TS to | Expt FIZ AC. Expt *14A.C. Loan Low oc ror Novas. oor WOwA C. | Vie RHEC. ! ! - Expt*t6 Ac : 2 i Pot. cou ie jaye WM jsan METER cou. A a | UNITY ef : 3 ' 1z 14 Lean : SECONDARY OFEN CIRCUIT * ee i ; rowwery oe METHOD POLARITY-AG METHOD Expt."I5A.C 1OV.AG. v Close voitage ewitches on WM and V only when taking readings. Close switch a only at start, for protection. 1-DG 2-DC 3-DC 4-DC 5-DC 6-DC 7-DC 8~DC 9~DC 10-DC 11-D¢e 12~DC 13-DC DIRECT-CURRWIT LABORATORY EXPERIMENTS General study of 4 Direct-Current Generator, and Motor. Operation of @ Shunt Motor. Operatton of a Shunt Generator, Measurement of Field and Armature Resistance. Saturation Curve of a Shunt Generator. External and Total Characteristics of a Shunt Generator. Armature Characteristic of a Shunt Generator, Armatura Reaction in a Shunt Generator. Saturation Curve of a Compound Generator. External and Total Characteristic of a Compound Generator. Armature Reaction in a Compound Generator. Speed Regulation of a Shunt Motor. Efficiency of a Shunt Motor by the Stray Power Method. Spe2d Regulation of a Comound Motor (Differential & Cumalativs). Operation of Shunt Gensrators in Parslicl. Operation of Compound Generators in Parallel. A.I Ee E. F. & E. Franklin Foster Gray Karapetoff Langsdorf .Morscroft S. & T. 5. &F. Smith Std. Hdbk. Pender Dawes R. & qT, REFERENCES Standardization Rules. "Elements of Electrical Rmginosring' Vel. 1, Franklin & Esty. "Dynamo Laboratory Manual". "Foster's Handbook", 7th Edition, 1913. "Principles & Practice of El2zctrical Engineering". "Experimental Electrical Envinosring". Vol. I Phird Edition, Vol. II Sacond Edition ‘Principles of Dirset Current Machines". "Short Course in Electrical Testing". "Laboratery & Factory Tests in Electrical Inginsering", Sever & Townsend. "Tasting of Electro-Magnstic Machinery," Swenson & Frankenfield. "Testing Dynamos & Motors. - "Standard Handbosk for Flctetrical Mmginsers". "Dirset Current Machinery". "Electrical Engineoring. "Direct Currents". Vol. I "Electrical Miginesring Laboratory "xperiments", Ricker & Tucker. SUPPLEMENT . Additional References M. & He “Continuous Current Circuits and Machinery" "Electrical Circuits and Machinery" Vol. I, II, IlI. Morecroft & Hehre. Expt. #1-Dc. Expt. #2-DC. Expt. #3-DC. Expt. #4-DC. Expt. #6-DC. Expt. #7-DC. Expt. #8-DC. Expt. #9-DC. Expt .#10-D6. Sxpt.#11-De. Expt. #12-DC. Expt -#13-DC. M. M e Me tol i M. M. M. Me Me M e & > @ He He He He He Vol. 1, Vol. IIl Vol. I, Vol.Ili . Vol. I, Vol.Ifl Vol. I, Vol.Iil Vol. I, Vol. I, Vol.Iil Vol. I, Vol. IIlr Vol. I, Pe Pe De p. pe De De Pe pe De. Pe pe Vol.III p Vol. I, Vol.III Vol. I, Vol.Iit Vol. I, Vol.Iil Vol. I, Vol.1It Vol. I, VYol.Iil pe pe pe pe pe i De De Pp. Pe 403-412, 20-31 390-399 3-14 396-399, 10-14 396-399, 10-14 385, 386, 238-251. 251-2533 253, 228-238. 400-402, 15-19 400-402, 400-402, - 15-19. 403-407, 413-418, 290-316, 42-46. 426-430, 263-271, 53-58. 263-2573 253-257; 253-2573 280-287, 293-3103 322-3523 422-4253 263-267; 431~4355 5 Me @ He. "Blectrical Circuits and Machinery" Vol. I, II, Iil Morecroft & Hehre Gherkins "Regulators" Expt. #1-AC. Me & He Vole Il p. 264-265; Vol.Iil De 100-109, Expt. Expt. Expt. ‘Expt. Expt. Expt. Expt. Expt. Expt. Expt. Expt. Expt. Expt. Expt. Expt. Expt. Expt. #9-AC. #10-AC #11-AC #12-AC #13-AC #14-AC #15-AC #16-AC #17-AC #18~AC #19-AC #20-AC #21-AC MT M. i pu if. Me Me Gherkin's ile So an & He & He Additional References (contd) Vol. II V81.IIL Vol. II - Vol. III Yol. {1 V¥1.IIT Vol. II Vol.Iil Vol. If Vol.IIl Vol. Il Vol.IIl Vol. Il Vol.iil Vol. IL Vol. IIL Vol. I Vol. II Vol. III Yol. II Vol.III Vol. Ii Vol.III Yol. I Vol. II Vol.IIil Vole I Vol. If pe. pe De ‘De Pe Pe Pp. Pp. De De. De pe Pe pe pe Pe pe pe De Pe De p. pe De p. Pe Pp. Pe 263-2643 100-109 263-266; 100-109. 265-273; 100-109. 276-286; 147-153. 345-359; 127-138. 345-359; 127-138. 360-381 ; 139-146. 360-361; 139-146. 92-99, 257-258, 316-319. 289-3243 110-118. 289-324; 110-118. 289-5243 110-118. 125-147, 447-449; 175-2093 72-74, 160-165. 543-3503 2735-2763 Regulators. Vol. I Vol. Il Vol. II Yol. II Yol. Il Pe Pe Pp. 125-147; 175~209. 289-324. 289-524. 289-324. Exot.# ss Pitla: Date Diasram of Conmections: Sketch neatly with pencil on a granh sheet the comiections as actually used in exveriment. Apparatus: Note name plate data of all machines used: Station ¢ Namo [ laks — — Nuvber Type Form J Yolts | Ameres arn “E.0. Frequency Speed Phase Instrumests: Gets take, mavbar, ete., of all meters, insttumente, and Wi soe Liensesa equ domant "asad. be ‘Uetor| Mace | tushsr [Medel | Type | Renge | Gepaci.y | Remarks _ nce halle ster atl womb Articis ]~ Mamtsr 7 parerist con lartiely (ister Begarl Tan” y ——Yy A wowed (a) Expt... Title _. _ Date inspection: ‘This should be made for every experiment performed, defects noted and corrected whenever possibla. 1. Is there sufficient oll ‘in the bearings? 2» Are the brushes badly worn?__sIncorrectly set? 3. Ie commtator rough or pitted? 4. Doas armatur? turn sasily? 5. Are all connections correct? 6. <Ar> couplings or b3led connections proporly madef, Fe | Is machine claar of toole and forsign particles? 8. Have your wiring inspectsd and OK'd by instructor, 9. Do oil rings turn ané provide sufficisnt lwerication after machine ‘$8 running? 10. Are thers any def2ct¢, and any unusual noiess in the wachine after it 49 rumning? . li. Note here the maxim and minimam currstt retings of aii the field rheostats you ugsé im the test. No. | Make Besistancs —_ poe mat Bot ies Note defects hare: (Correat thom, if pessibie) (o) fl-DC 1. GENERAL STUDY OF A DIRECT-CURRENT GENERATOR & MOTOR This shozt is to help you get acquainted with the apparatus you ‘will us? most frequontiy in your Laboratory work. Check and fill in all the required blank spaces as quickly as possible. If in doubt about ons or anothar, proce3d with the rest, omitting that one until assistance can b3 given you. Typ? of Dynamo: Direct Current Doubls-Currant Shunt Series Compound. __ Commutating-pole . Armature: Ring_ Drum Lap Wav 2 No. of slots Conductors per slot E.M.E. Current Watts Output Active lsngth Circumference? in feat Sp3e2d, repsm Peripheral speed, ft. per minuts Commtator: Activa length Total length Circumference in ft. Poripharal specd, ft. per min. Total No. of bars No. of bars between brush3s of opposite polarity. Averags voltage between bars Width of bars Width of insulation . Brushes: Material Bare? Copper coated? Width Thickness _ No. per set No. of s3ts Brush area psr-set Currant density in brushes, arm. {int Tension of sorings on brushes, lbs. Field: No. of coils Porm-wound? Hand-~wound? Neo. of poles Pole pitch (inch3s)_ (mach. degrees) (alec. do2grses) Pole width Pole length (axial) Width of pole shoe Length of pole shoe (axial) Width of commutating pola Length of commutation pole (axial) (ec) #1-DC TI. OPERATION OF A SHUNT MOTOR Procodure: jl. This test is to teach you four important and essential things concerning a Cirect-current motor and three concerning the use of ammeters and voltmeters. They are for the motor, (a) the method of ‘connection, (b) starting, (c) changing speed, and (d) reversing the diraction of rotation, and for the moters, (a) the proper method of interchanging am-eter lead connactions, (b) protecting ameters by means of a short-circuiting switch, and (c) protecting voltmeters and yoursolf by properly interchanging lead connzetions when necessary. As you will uso d.c. motors and metors in practically 2.v2ry oxp2riment you perform, it is to your advantage to momorizs th3s2 sive points imoodiately. 2. Us3 a low-rang> amm2tor in the fisld circuit, a high-rang? ammeter in the lina, and a high-rang> voltmeter across th3 terminals of the line switch. 3. Adjust th? ficsld rhtostat so that all resistanc? is out. “Soe that all amoster short-cireniting switches are closed. 4. ‘Obs .rve if tho voltmeter is rovorsed. If so, interchange its load conmnictions at the linoeswitch. Naver rovers? lead connections at the voltmoter terminals. 5. Closs the lines switch, rais? tho starting-box handl> to the first notch, and note the dirzction of rotation of the motor. If the rotation is ancorrsct, pull the lin? switch immediately and before reloasing the starting-box handl>. Thon reverso sithor the lead cormection at the field tarminals, or tos). at th? armature terminals, and proceed as before. 6. If the rotation is correct, procesd to move tho starting-box handle gradually from one netch to the noxt until it ergages th: cateh and stays in th2 upright position. 7, Before opaning tho ammeter short-cireuiting switches 3s2 if the motors are indicating in th> proner sens2. If not, ths lead connsctions at the meter tsorminals may bo interchsmged while the short circuiting switch is closed. 8. Tako raadings of ths line voltag? or eleetroemotive forces, armature currant, field currant, and speed, for fisld resistance out and also in. Do not pormit tha motor to spesd up excessivoly. 9. Reverse the direction of rotation of the motor. While startins, observe the fluctustions of ths armaturs current as the starting resistance is cut out. (4) PleDC__Proczdure Cont'd. Data: Tabulate all obsorvations on 2 standard data shoct. Quostions: Answors to questions 1-6 inclusiv? should be approved before starting ths t2st,.tho romaindsr to bo answered in the final raport. 1. State the function of a motor. 2.. What is (a) a shunt motor? (bo) a seri2s motor? (c) a compound motor? (d) a differential motor? 3. Compare the fisld resistance of a shunt metor with respect to its armature r3sistanc:. Why ars they diffrent? 4. Why is a starting rosistanc? nocessary and wrere is it placed? 5. State two methods for reversing the dirosction of rotation of @ shunt motor. 6. How can you regulate the sp3sd of a shunt motor? 7. (If the motor gave troubl3 in starting, to which of the follow- ing caus3s was it dus? (a) Groat overload praventing the turning of the armature. (b) Excessive friction in some part. (c) External or internal circuit open. (d) Wrong connections. (oe) Armaturs revolved at axcessivs snecd. (f) Armature revolved in wrong direction. (g) State any other cause. 8. Did the rasults chock your answers to (4), (5) a.nd (6)? References: $2.27. | pp. 3-6, 27+29, 64-66, 68-69. . Langedorf Art. 31, 60, 127. ' Gray Art. $2638, 86, 93-96, 100-101, 104, 401-404. Smith pp. 116-121 E. & F. Art. 26, 59. A.I.E.2. Definitions Std. Hdbk. Definiticns in Standardization Rules section. Pender p. 40, 198. Dawes p- 309. Karape toff p. 340 Vol. I. R. & Tf. p. 107, 128. (e) 10 r1L-DC DATA SHEET Station, A 3 | ¢ D=B-+-C E=AD Field| R.P.M. Volts | Arm. Fld fotal Watts Rheo. |# + tid ? Out In* *Do not permit the motor to speed up to oxcessive values. (£) Approved Expt-# 0 Pitle: | Date Diacram of Comections; Sketch neatly with pencil on & graph sheet the i: connections as a tually used in experiment. Apparatus: Note name plats data of all machines used: Station #¢ Name | Make | Mwrber Type Form 4 —— Volts | Amperes Kee H.P. | Frequency Spend Phase instruments: Noto make, mumbor, etc., of all meters, inetrumsnts, and miscellenceua equipmant used. Meter) Make itanpsr | Model | Type Remge Capacity Remarks q term il 4 Wen feed oe ae nar te oa Articis | Sumter aserintion Articia } Number” | DsserT TA] | ‘ (a) Expt. Title : . Date Inspection: This should be made for every experiment performed, defects noted and corrested whenever poseibl 3. 1. Is there sufficient ofl in the bearings? ~— 2. Are the bruchee badly worn? neorrecatly sat? Z. Is cemmtator rougn or pitted?_ 4. Do3s armatur? tun sasily? 5. Are all connsctions corract?. 6. Ar3 couplings or ba3lt:d connections properly madef 7. Ys machine clear of toole and forsign particiss? 8. Have your wiring inspectid and OK'd by instructor 9. Do of] rings turr. and provide sufficiont lubriceticn after machina ds romnding? 10. Are there any defechs, and any unusual noises in the machine after it i3 running? mee 11. Note here ths maxim end minimum currant ratings of all the field rheostats you ug3d in the test. No. | Mace Rasistance Currant Rating Note defects here: (Corrset thom, if pessinie) (>) | re Seen eens il #2~-D6 OPERATION OF A SHUNT GENERATOR REMENT OF FISLD AND ARMATURE ERSISTANCE Procedure: I. Qperation of a Shunt Generator. 1. This test is to teach you five important and essential things concerning a dirsct-current generator. They are; (a) the method of connsetion, (b) building-up tha voltage, (c) correcting one of the mest common hindrances to building-up, (d) varying tn voltag?, and (2) a common method of leading. As you will us2 a d.c. gonorator frequently in all your laboratory work, it is to your advantage to memorize theso fiva points inmcdiataly. 2 Use a low-rang>s ammoter in the fisld circuit, a high-rang? voltmeter across tho armatur? terminals, and @ higherangs ameter in the lines. 3. Have your connactions chacked & OK'd by instructor . 4 Adjust the goncrator fisld rhzostat so that all resistence is in. S23 that all amster short-circuiting switches ar2 closod. 5. Record thd voltag? dus to rosidual magnetism. 6. Cles2? the fisld switch, gradually decrease th? fisld circuit rosistancs and note th: voltcoter carsfully. If the voltage does not increase, insert all tho resistanc2, opm the field tch and reverss th2 leads at tho fisld terminals. Rafer to qasstion (11). 9%. Adjust th? voltags mtil its valw is about 110 volts, or the rated voltazs of ths machins, and reenrd. 8 With tho water rheostat plates out, @losa the 11 carsfully low2r ths rheostat plates into ths water wmtil indicates full-load current. Record the voltags. * tA ca etal ina aeaeen an in oo Va. by a 9. If pessiblsa adjust the fisld rasistanee until th2 volta, ths samo as it was at no-load, and racord. “10. With the sonsrator rumning at constant speed and shift the prush3s ; @ short distance arcumid ths com rasults. Do not pormit the conrutator to spark axevssivel Ltr. ll. Reverse the fisld connections after removing ths Loud ond opening ths fisld switch, and nete the 2ffect on the wossibilitr of bringing up the voltage, (a) 12 #2-NC Proeaiur3 contd. I. Measurement of Fisld Resistance. ——- 1. Use 2 lowerang? wmcoter and high-range voltmeter. 2. Hava your wiring inspected and OKtd by instructor, Z. §929 that moters are pronerly protects2d and oxternal fidld rasistanco is in. 4. Close the fisli switch, adjust the rheostat for a certain value of current and read the voltaga. 5. Rep3at for at least two difforent current valuts. II. Measuroment of Armatur2 Resistance. oe This test is mado frequently and should be memorized. a. Lap Winding. 1. Lift all the brushes from tho commutator. Do not chango the brush-holder ssttings, but relaase only the springs. 8 Use a low-range amcoter and voltsetar and tho special leads provided for the purposs. 3. Have your connoctions chacksd & OK'd by instructor. 4. Hold th> 2nds of the special leads on diametrically opposite segments of the commutator, adjust the rhjostat for a certain value of current and reali the voltage. 5. Repeat for at least two different current valuss, 6 Calculate the resistances from the data by Ohm's Law, rultinly this by four and divide by the number of poles squared. This is ths true running resistance. b-Wave winding. 1. Lift the brushes from the commtator. Do not changes tas orusl- holder settings, but release only ths springs. . 2- Use a low-rang? ammeter and voltmeter, and the special liads provided for th? purpose. 3. Have your connections checked & OK'd by instructor. (4) . 13 #2-DC . Proerdura contd. 4 Hold the onds of th? syecial leads on commutator segments 180 oloctrical degrets apart, i.9. on segmants ssparated a distance equal to that between adjacent positiv> and negative brushes. 5. Adjust. tha rheostat for a certain value of current and read tho voltage. 6. Repeat for at least two different current values. 7.- Caloulats the resistance by Ohm's Law. This is the true running rasistanc>. Date: Tabulate all observations on a standard data ‘isheat. Questions: Answ2rs to quostions 1-10 inclusiv:? should »o apnprovrd before starting the test, the remaindsr to be answered in the final raport. 1. Stat? Ohmts Law in words. 2 Why is tho armature rasistancs made low, and the shunt fisld rosistancs high? 3S. What is m3ant by brush contact resistance and how does it vary with ths currint for carbon brushes? 4. How would you obtain th> resistance of several differant parts of a ssrizs circuit? 5. Why should the armaturs romain stationary whils measuring its resistance? 6. State the function of a generator. 7. Wam? the thr32 types of dirsct-current gansrators and show thoir differsnees by diagrams. 8. Why should all the resistance of the fiszld circuit be in pefore closing the field switch? 9. What method of resistancs measurement is gonsrally most convenient for motors or gamn3rators? ~~ Q ne 14 #2-DC Questions contd, © 10. Explain a second mothod, stating its principle, the procedure, and its advantages. ll. If the gonerator failed to excite to which of the following causes was it dus? (a) Residual magnstism weak or not prosent. (b) Rovorsed field connections. (ce) Short-circuit, either in the machine or oxternal circuit. (da) Fiold coils opposod to oach othor. (e) Open circuit in the field coils or connections. (f) Brushis not in proper position on tha commutator. (g) Rhsostat in the field circuit of too groat resistance. (h) State any other cause. 12. Explain ths variation in tho voltage obtained at full-load and no-load. 13. Explain why adjustment of the field current enabled you to vring the voltage to a value cqual to that at no-load. In case you were unable to bring the voltags back to normal sxplain why. 14. What occured when you closed the field switch and gradually cut out tho resistance in tho fisld circuit? Explain this action. What prevents its continuing indefinitely? References: 5. &T. pp. 3-6, 21-25, 29-31. Langsdorf Art. 51-56, 58-59. Smith pp. 713, 54, 73. F.&k. Art. 31, 49. A.I.E.E. Definitions. Std. Hdbk. Definitions in Standardization Rulos Section Pander p-34, 147. Dawes pe 48, 215. Karapetoff pe 3, 287, Vol.I; pp. 188-207, Vol. TI. R&T. p» 74, 7%. (f£) 15 #2-DC «DATA SHEET Station: Field Resistance Armature Resistance Amp. Volts Res. (Wave Winding) i # ohms Amp. Volts « ‘Res. # . ia ohms Av. _ Avi Armature Resistance Lap Winding) A B C=B/A D adc /De Amp. Volts Res. Ho. True Rea. ohms poles chms | Ay. Volts | Line | Field Amp. Amp. id ft r Dus_to résidual magnetism 4 - No-load voltage { . L _— Full-load voltage before adjustment 4 Full-load voltage after adjustment Brushes on neutral Brushes maximum forward * A Brushes maximum back * ! * Do not permit commutator to spark excessively. Approved: (g) Expt.# Title: Date Diagram of Connections: Sketch neatly with pencil on a graph sheet the comnections as astually used in experiment. Apvaratus; Note name plate data of all machines used: Station # Name { Make Number Type Form _ Volts | Ammeres K.W. H.P. | Frequency Spesd Phass Instruments: Noto make, number, etc., of all meters, instruments, and miscellanscus equipment used. % Meter, Maxe {| Number | Modol Type Range Capacity | Remarks . 4 ‘Articis | Mumber [Deseription Artists 7 cker (a) tnapiemntinamrenyfeemmenceepenis Title | __ ___Date_ Inspection: This should be made for every experiment performed, defects i. Fe 8. 9. ii. noted and corrected whenever poseibla. Is there sufficient e411 in the bearings? __ Are the brushes badly worn? Incorrectly eet? _ ie coammmtator rough ér pitted? Deas armatur3 turn sasily? Are all comnectiona eorrsct? Ar? couplings or b3alted connections properly made? Is machine clear of tools and forsign particles? a Have your wiring inspectad and OK'd by instructor, Do oil rings turn and provide sufficient imbrication after machins ‘49 runing? | aunemntentennen command Are thore any defects, end any unusual noiese in the machine after it 48 rumning? Note hers the meximm® and minimom ¢urrmt ratings ef fll the field rheostats you ugtd in the $4s%. No. | Make Ras istance : Curr mt Rat Le Note defects hera: (Correct thom, if pessibie) (o) 16 - -#3-DC SATURATION CURVE OF A SHUNT GENERATOR Procedure: 1. Use a low-range ammeter, a high range voltmeter, and a high resistance in the field circuit. Do not use a field rheostat with a current capacity less than the field current used. 2. Comect the generator for ssparate excitation and start it -as per instructions in #1 & #2-DC. 3. Before closing the field switch rscord the voltage due to residual magnetism. 4. Turn in all of the field circuit resistance, close the field switch and read the field current, and corresponding armature voltage. 5. Keeping the speed constant throughout the test, dscrease the field resistance in about tan steps, taking simultaneous readings of field current and corresponding armature voltages. Always bring the magnetizing current up to the value; do not carry it above and then reduce it. If the speed varies, corrzctions for voltage readings should be made. 6. If you should unavoidably reduces the current, it is necessary to insert all the resistance, open and close the fisld switch, and bring th® current up to the desired value again. 7. After all the field resistance is out, insort it again in about ten stops, taking readings as bsfore. This tims approach the curront value from one higher up and do not raise it at any time during the descent. Your last reading should be the voltage dus to residual magnetism. Data: Tabulateall observations on a standard data sheet. Cirves: Plot the saturation or magnetization curve on a standard curva sheet, using volts as ordinates and field currents as abscissae. Follow instructions given in the goneral directions. (c) 17 #£3-DC Procedure contd. uestions: Answers to questions 1-7 inclusive should be approved before starting the test, the remainder to be answered in the final report. 1. What is meant by "characteristic curves of a generator? What are their functions? 2. What is the magnetization or saturation curve of a gensrator? Name two of its functions, 3. What is tho internal characteristic or building-up curve of a generator? Name its function. 4. What is maant by ssif~ and separate excitation? By ampere-turns? By magnetic saturation? By magnoto-motive-force? 5. Doss the flux increase proportionately with the voltage? 6. If the speed varizs, how can the voltmeter readings be corrected? 7. Suppose too great an increas? is made in the ficld current and then it is reduced directly to the required valu>, what effect is produced on th? curv? and why? How would you attain the required value without producing this effect? # 8 Explain why th> curve first runs up straight, then bends over. 9. Explain why the curv: cuts the vertical axis above the origin, and the important bearing this has on th>2 operation of self-cxcited gensrators. 10. At what point on the curve should the no-load voltage usually come? What is the eff:ct on the action of ths generator of having 1% lower? What is the effect of having it higher? ll. What is meant by hysteresis? How are its effects shovm? 12. State two sffects of tommeratur2 ris2 on the yoltass of a generator. Which effsct is greater? Are they additive or subtractiva? ‘Explain. (4) #3-DC Procedure contd. Rsferences: $.&T. pp. 3-6, 32-37. ‘Langs4orft Art. 54, 59, 78-79. - Gray Art. 78-79, p. 371. Smith pr. 41~53. F.& &. pp. 384-386. Foster p. 336. A.I.E.E. Definitions. Std. Haok. Definitions in Standardization Rules Section. Pender pp. 83, 84, 299. Lawes Pp. 258-262. Karapsteff PP. 289-294. R. & T. p- 77. (e) #3~DC DATA SHEET Station: Magnetization Curve Going Up Coming Down Volts + Fld. Volts Fld. Read | Correct Amp. R.P.M, Read (Correct Amp, R.P-M. # # # _# # # Approved: (£) Expt. Title | Date Diagram of Comnecticns: Sketch neatly with pencil on a graph sheet the comiections as actually used in experiment. Apparatus; Note name plate data of all machines used: Station € Name j Make Niurber Type Form Volts | Amereg mv. H.?. | Frequency Speed Phass Notes makc, mumber, etc., of all meters, inetrumants, and miscellancsess aquipmant used. ‘Meteor, Uaxe | Nacbor [Model | Type | Rangs | Capacity Remarks t Sd “4 sano 1 ne A oem apis Fem ato be Articis 1 fumber éecription || Artiels 1 ‘umber | Degerie ston” (a) ; ‘Expt. Title | Date Inspection: This shoula he made for every experiment performed, defects — noted and corrected whenever possidls. 1. Is thers sufficient oil in the deacings? 2. Are tha brushee tadly worn? Incorrectly sot? ‘z is commutator rougn or pitted? 4. Doss armature tien sasily? 5. Are all comnections corrsct? 6. Aro couplings or palted connections properly made? 7. (Is machine clear of toole and forsign particies? 8. Have your wiring inspectad and. OK'd by ine tractor 9. Do ofl rings turn and provide sufficiant lubrication after machina ‘$8 running? 10. Ars there any defects, and any unusual noises in ths machine after it is muoming? ened ll. Note here the maximum end minimum current ratings of all the field rheostats you used in the test. No. feice sistance Current Rating Oams Vax. Mines — Note defects hers: (Correct them, if possible) (b) 20 #4-DC " EXTERNAL & TOTAL CHARACTERISTICS OF A SHUNT GENERATOR Procedure: I. External Characteristic l. Use a low-range ammeter in the fisld circuit, a high-range ammeter in the line, and a high-range voltmeter. 2. Start the generator and bring the voltage up to rated value as por instructions in #1 & #2-Dc. 3. Kreping the spesd and tho fizld resistance (not ficld current) constant throughout the test, tako simultaneous readings of the terminal voltag2, line current, field currant, and speed for zero output and for increasing values of load. Try increasing the load until tho machine fails to gonerate. Il. Total Characteristic 1. Use a low-range ammeter and voltmeter. 2. Determine the armatur> rosistance by the voltage-drop method of #2-DC. 3. To the drop due to armature resistance add one volt per brush (total 2 volts) to account for brush contact drop and armature leads, and calculate th3 valuas for the total charactsristic. See A.I.E.E. Standardization Rules 440, 442-444, 454, 819. Data: Tabulate all cbhservations on a standard data shest. Curves: Plot the external and total characteristics on the same standard curve shest, using external or terminal volts as ordinates and line currents as abscissas for the external characteristic, and total volts as ordinates and total armature currents as abscissas for the total characteristic. Follow instructions given in the general directions. . Questions: Answers to questions 1-6 inclusive should %¢@ approved before starting the test, the remainder to be answered in the final raport. 1. What is the external characteristic eurvs of 4 shuwit generator? (c) 44-D0 Qusstions, contd. 2. What is the total characteristic curve of a shunt generator? 3. What causes the terminal voltage of a shunt generator to decrease as its load is increased? 4. When do both the current and the terminal voltage ranidly decrease? Why? How doss this affect short-circuiting a shunt generator? 5 Why should the field resistance be kept constant during the test? 6. Why should the brushes be kept stationary during the test? ° 7. Give two reasons why the total characteristic departs from a horizontal line. “ 8. How is the oxternal characteristic affected by reducing the armature conductors to one-half the original cross saction? Why? 9. Explain why the voltage corresponding te a given current cannot be corrected proportionally to speed. Roforences: 5S. & TT. pp. 3-6, 38-40. Langsdorf Art. 114-116. Gray Art. 81-82, p. 372. Smith pp. 76-82. F. & E. p. 149. Pender pp. 147, 292. Dawes pp. 288-295. Karapetoff pp. 299-303. (4) we BN (s) 24—DO DATA SHEET Station External Characteristic Line Field Total Volts Speed Amp. Amp. Amp. Const. i # ia i ¢ Total Characteristic (calculated) _ Total Ext. Arm. Arm. RI Brush Total E.M.F. Res. Drovs Con, Drop E.M.F. Amp. Volts Ohms Volts Volts Volts | i Armature Resistance Armature Resistance __ (Lap Winding) . (Wave Winding) _ : A.B G=5/A Db [e=40 7b? kp | Volts les. Amo. | Volts Res. No. | True : sh Ohme : # Onms {Poles | Ohms ~——— 7 AY a av Approved: Exot. ¢ Title: Date Diagram of Cormecticns: Apparatus: cennections Note name plate data of all machines used: Sketch nea atly with vencil on a graph sheet the aS actually used in experiment. Station # | ___diams Meke Nutber Type Form - Voita | imperes KW. ” g.P. Frequency Sposd Phase . “} instrumenta; Nota make, rranibor, etec., of all meters, instruments, and miscellanzcns equipment usad. . (Meter| ake | Naubor [ifoisl | type [ Range | Capacity Remarks | y eet Articis | Number ascription Articis 1) Sister] Doser ts tten (a) tr ot Ria + etn gametes “Rept. __Tit14_ _ Date_ peetion: This should he made for every experiment performed, defects noted ard comrected waensver poseidla. 1. Is there suffictant oi] in the peavings? ey Are the brushes badly worn? Incorrectly g2t? oe Ie cemmitator rough er pitted? 4. Doss armatur? turn sasily? 5. Are all comsoctions correct? 6. Ara couplings or belted connections proporly mad? 7. Is machine clear of toole and forcign particles? 8. Havo your wiring inspactzd and OK'd by instructor 9. Bo oj] rings turn and provide sufficiant iubrication after machina ‘is running? 10. Arg there any defects, and any unusual neoisse in che machine after it is ranning? rod 11. Note here the meximm end miniimm currant ratings cf all the field rheostats you used in the tast. , No. | Make Restatance Current Rating BES Mex. iin @ a, Note defects hats: (Correct them, if peasibls (b) | a eee 23 #5-DC ss ARMATURE. CHARACTERISTIC OF A SHUNT GENRRATOR | ARMATURE REACTION IN A SAUNT GENERATOR Procedur?3: I. Armature Characteristic. lL Use a low-range ammeter in the field circuit, a high-range ammeter in the lines, and a high-range voltmeter. 2 Start the generator and bring the voltage up to rated value as per instructions in #1 & #2-DC. 3. Keeping the speed and the voltage constant throughout the test, take simultaneous readings of the terminal voltag2, line current, field current, and speed for zero output and for increasing values of load. II. Armaturs Reaction: 1. Rapeat Part I, but with this difference. Uss separate excita- tion for the field, allow the voltage to change, but keep the speed and the fisld current constant throuchout the test. 2. Determine the arvaturs resistance by the voltages drop method of #2-DC, calculate the total armature and brush-contact RI drops, and hanc3, the voltage drops dus to armatur3; reaction. Data; Tabulate all observations on a standard data sheet. Curves: On a standard curve sheet plot the armature characteristic curve, using field currents as ordinates and line currants as abscissas. On a second standard curve shest, plot four curves, using lina currents as abscissae in seach cas2, and as ordinates: (1) the ohserved terminal volts. (2) the total volts developed (terminal volts plus armature and brush-contact RI drovs). (3) the volts due toa constant magnetomotive-force (a hori- zontal line at a value equal to th? no-load volt«ze). (4) th: voltage drops dus to armature reaction (the difference in voltages betwesn curv2s (3) and (9)). Follow instructions given in the gensral directions. (ce) 45D - Procedure contd. Questions: Aaswers to questions 1-5 inclusive should »e approved DSefore starting the test, the remainder to be answered in the final report. 1. Waat is the armature characteristic of a shit generator? What is its function? 2. That is meant by flat-commounding? Ry over-compowiding? 3. How could you determine the ssries turns r2quired for compound- ing by means of added turns? 4. How would you determins the number of turns actually in the shunt or s:ries winding by the uss of added turns? 5. Define armaturs reaction. How does it affact the FE.M.F.? 6. If the machine you tested has 1200 shunt field turns ner pols, how many seriss turns per pole should %e added to change it into a flat-compounded ¢gin2rator? 7. What caus3s the slope of the arzaturs characteristic to in- erzas3 with incrzas2d currents? 8. How would tho number of turns raquired for 10% ovar-compound- ing comar? with the number roguired for 547 Why? What additional realings would b3 n2c3assary to dstarmine this? Referzness: 8. &T. pe. 3-6, 40-41, 45-46, 49. Langsdorf Art. 91, 92, 109, 162. Gray Art. 75-77, 83, 92, 98. Smith pp. 54-62, 67-69, 105-109. F. & HE. Art. 77, 78, Aoo.3. Art. 34. S. &F. pp. 155-167. A.I.E.F. Definitions. Std.ndbk. Definitions in Standardization Rules Section Pender pp. 159-161, 116-136. Dawes pe. 300-301, 267-276. Karap atoff po. 305, 316, 441-446. (a) (9) Aporoved #5-DC DATA SHEET Station | Armature Characteristic : Dine Field 1 Volts Speed | . Amp. Const. Const. Li # _# ri — ansinet (iemen iainaein r { [ ; Armature Reaction Fld.Amp.| Lins | Volts | Speed Arm. RI ; Brush Total Arm. Const Arp. | Const Drop »Con.Drp.] RI Reaction ‘ i 4 Armature Resistance Aruaturs Resistance (Lap Winding) 2- Vave “indine) A 3 c=B/A | D E=46 /D Aion Volts j Ras. Amp. | Volts | Ras. {| No. Trus _ # re Iams ; Poles| Res. “ se fer es x Ohms eee one some 1 a des rete ne eet cg ied : Ay _—! i AY 4 ‘Expt. # Title: Date Diagram of Connections: - Sketch neatly with pencil on a graph sheet the comnections as actuzlly used in experiment. Apnaratus: Note name plate data of all machines used: | Name | Meke oo! Number Type Form Z Voits ‘dAmeres | KW. 7 H.-P.) Frequency [Speed Phasa Instruments: Noto makc, number, ete., of all metars, instrumonts, and miscellancene aquiomant used. Meter, Make | Warbor Model | T pe Reng? Capacity Remarks . ne Se Me won an » ond sessed eet eta ae . i (a) -‘Bzpt. Tyetle neni | Date Inspection: This should be made for every experiment performed, defects noted and corrected whenever possibls. l. Is there sufficient ofl in the bearings? 2s Are the brusnee badly worn? Incorractly set? ze Ie cemmtator rough er pitted? 4. Doas armatur? tun easily? 5. Are all connections corrsct? 6. Ar2 couplings or belted connections proverly made? 7. Is machine clear of toole and forsign particiss? 8. Hava your wiring inspectid and OK'd by instructor 9. Do oil rings turn and provide sufficient lubrication after machine -is ronning? 10. Ara there any defects, and any unusual noig2a in the machine after it is running? ae 11. Note here ths maximm end minimm current ratings of all the field rheostats you us3d in the test. , No. | Maxe Resistance Currant Rating amc: _ Note defects here: (Corrset thom, if possibile) (b) | 26 7 #6-DC SATURATION CURVE OF A GOMPOUND GENSRATOR Procedure . i. Follow instructions 1-6 of #3-DC, Part I, bringing voltage only up to the normal rated value. Keep the series field circuit open. 2. Use a high-range ammeter and a load-rheostat in the series field cirenit. 3. Xseping the maximum shunt field currant obtained in (1) constant, clos? the series field circuit and gradually decrease the resistance of the loai rheostat, taking readings of the series field current, shunt fisid current, terminal é.m.f. and speed for a range of currents up to the full-load valu: of ths machine. ff the e.mf. falls with increase in series field current, ravorss the series field connections. Observe the same procautions as in (1) about approaching the next value of am.f. from ons below. : 4. Decrease the current in ths sorios fisld, taking observations as in (3) ani approach values of ¢.m.f. from highsr values. 5. After reaching zero current in thse seriss field, open its circuit and then proceed as in (7) of #3-DC, Part I. 6. Ths ratio between the ssriss and shunt turns is obtained as follows: (a) Operating the gonerator at normal spsed excite only the seriss field bringing the armaturs terminal voltazs to a suitabls valu. Record the series field current and ths terminal voltage. (b) Then excites the shunt fizld alons bringing the armaturs terminal voltage to the valug obtained in (a). Record the readings as befors. Take at least thrae different ssts of readings in gach case. The turn ratio is thon equal to th3 shunt ficld current divided by tha serizs fi2ld curr2nt which producad the sam? voltag:. The equivalsnt shunt field valu2 of the series field currant is equal to th> product of the ssriss fizld current and tha turn ratic. This equivalent values should 6@ added to the shunt field current to obtain the total magnstizing current. Data: Tabulat2? all obs2rvations on = standard data shest. Curv2s: ' Plot the saturation or magnetization curvys on a standard curve shest, using volts as ordinates and total magnetizing currents as abscissas. Follow instructions givon in the general directions. (c) 27 #6-DC Procedure contd. Answers to questions 1-5 inclusive should be approved »efore starting the test, the rsmaindsr to »e answered in the final r>port. id. What is maant by equivalent shunt field valus of the series fisld current? What constant should io datarmined in order to find this current? "Explain in dstail how to obtain it. 2. Comar3 tha current ratings and risistanc> of ths rhsoostat usal in the shunt field cirenuit with that used in th: sories fisld circuit. . . 3. Could the series fisld bes excited from a low-potantial source in this t2st? State any advantages in doing so, 4. How can th? valu: of currant in th? series winding b3 regulated undar normal. cunning conditions without changing the load? If so regulated, how might you determin3 its valus? 5. How can the valu? of currant in ths shunt winding be regulated? 6. What hxappons when loading 2 compound gensrator if the serics wirding is rovorstd with raspict to the shunt windine? 7. What is the alvantags of a commound g2narator? What is the funetion of tha shunt winding? Of th3 series winding? 8. What 2ffset vould a short-circuit on a compound gamerator produce comparzd with that on a shunt gonesrator? Reofarwne3s: 5. &. pp. 3-3, 48-47, 49-52. Langsdorf Art. 53-54, 55-59, 78-79. Gray Art. 78-79, ». 371. Smith mp. 41-53. FL. &, po 80, 364. qmder oo. 83, 171. Dawes yp. 256, 295. Karap 2toff p. 313, R. &T. op. 88. (4) 28 #30 DATA SHEET OS Station Saturation or Magnetization Curve Volts Ser. Fld. Eq. Sht. Sht.Fld [| Total Read Correct Amo, Amp. Amp. Magnet Speed # ; # Amp. Const. # A B=AK C D=B+C # Ratio Data Volts Sht. Fld, Ser. Fld. Spead E F Keu/F AY Aporoved Expt. ¢ Title: Date Diagram of Cormections: Sketch neatly with pencil on a graph sheet the Apvaratus: Station # Note name plate data of all machines used: connections as actually used in experiment. Form Name | | Make Number Type : Volts | Ammeres K.E. H.?. Frequency Speed Phase Instruments: Noto makes, mumbar, ete., of all meters, instrumants, and miscellanicus equipmsnt usad. Meter, Make | tramber | Model Type Renge | Capacity Remarks ' a { Articls | timber | Description Articls f (a) Title a | Date Inspection: This should be made for every experiment performed, defects l. 2s Are the brushee badly worn? Incorrectly s°t? noted and corrected whenever possivla. Is there sufficient ofl in the bearings? Is commtator rough or pitted? _ Doss arnatur? turn aasily? Are all comections corrsct? Ars couplings or belted connections properly made? Is machine clear of toole and forsign particles? fave your wiring inspect sd and OK'd by instructor De oll rings turn and provide sufficient lubrication after machina 1/48 rumling? Ars there any defzcts, and any unusval nois?s in the machine after it is running? Note hers the maximm and minimum currant ratings of all the field rheostats you us2d in the test. No. {| Meco Resistance | Currant Rating Gams Max. i Min. Note defects hera: (Correct them, if possibin) (b) 2g - #2-DC EXTERNAL & TOTAL CHARACTERISTICS OF A ‘ SOM OUND CEUNERATOR Procedure: ‘I. Compound or External Characteristic, 1. Use a low-range ammeter in the field circuit, a high-range ammeter in the line, and a high-range voltmeter. . @ Start the generator and bring the voltage up to rated value as per instructions in #1 & #2-Dc. 3. Apply a load and note if the e.m.f. rises, remains constant, or falls. If it falls with load increase, remove the load, open the shunt field circuit and reverse the series field connection at its ter- minals. , 4. Kesping the speed and the shunt fisld resistance constant throughout the test, take simultaneous readings of terminal e.mf., lines current, shunt fisld current, and sp2ed for zero output and for a soriss of valuzs of current output ranging from no-load to full-load value. Il. Total Charzcteristic. 1. Determine the armature ani seriss field risistance by the voltago~drop mathod of #2-DC, calculats the total armature and brush- contact FI vrop, and hencs, ths total characteristic valuss. Data: Tabulat2 all observations on a standard data shost. Curves: Plot thse external and total characteristic curv3s on the same standard curvs sheet, using terminal volts as ordinates and line currents as abscissa? for the external charactaristic, and total volts as ordinatss and total armature currents as abscissas for the total characteristic. Follow instructions given in the general directions. Questions: Answers to quastions 1-4 inclusiv2 should be approved before starting the test, ths remainder to be answered in ths fincl report. 1. Explain the difference dstwoen long shunt and short shunt connections using diagrams. (c) 30 #9-DC Questions contd. 2. What is wrong with a compound generator, if the voltage decreases rapidly as the load increases? What must be done to remedy tnais? 3. If the voltage is found to ris3 considsrably with load in- crease how can it be remedied? 4. Explain the actions of shunt and series coils in producing the compound characteristic. 5. What would be an ideal "flat"-compound characteristic? How will the actual "flat" compound characteristic differ from the ideal and why? 6. Under what circumstances might a rising characteristic be required? What is a machine giving such a characteristic called? 7. What would be the effect on the characteristic of a flat- compound machine if it wero onerated (a) with no-load veltage normal and speod 90% normal? (») with no-load voltage 90% normal and spo2d normal? (c) with both no-load voltage and specd 90% normal? (d) with no-lcad voltag2 normal and sp32d 110% normal? (2) with no-load voltage 110% normal and speed normal? (£) with both no-load voltage and spesd 110% normal? 8. Compare ths sffects of long and short-shunt comactions on the external & total characteristics of a given machine. Referonces: Ss. & T. po. 3-6, 45-50. Langs dorf Art. 56, 118-119. Smith po. 99-106. F. & BE. pp. 47, 48, 497. Pander - po. 57, 153, 171, 176. Dawes pp. 295~301. Karap2toff po. 313-319. R. &T. po. 88-93. (a) ol #700 DATA SHEET Station External Cheracteristic Line Fisid Term. Sneed Amp. Amp. Volts Cons*. HE. ¢ é # Total Characteristics (Calculated) Line i Series | S¢e.Fld. lSh.Fid. | Total jArm.{| Arm. {Brush |Total [Term. | Total Amp. Fld. RI Drop! Amp. Arm. jRes. {RI Drop }Qon.Drp.jRI Dp. + Res. | Volts i# Arm. | Ohms lVolts Volts |Volts [Volts [Volts A B CAB D B=AiD | F Gane H T8G+e! K jL=I4k 4 L.. L Armature Resistance (Lap Winding) . A E} C=B/A D B=46 /D° Amp. Volts Res, No. True Res. fia # Onms Polss Ohms Armature Resistance Series Fisid | (Wave Winding) Resissarce Z Amp. Volts Res. Amp. Volts Res. , AY. ‘Ay _ (e) foproved Expt.¢_____Pitle: _ | Date Diagram of Cormections: Sketch neatly with pencil on a graph sheet the connections a3 actually used in experiment. Apvaratus: Note names plate data of all machines used: tee cbenecctnrmmaronenentes weeds septate. ~ . Station # Name Make Number Type Form “ Volts | Ammerag KW. H.P. , Frequency Snead Phagea instruments: Not2 maka, mumbar, etc., of all meters, instrumants, and miscellantceus squipmant used. Meter, Maze Number | Model Type Range Capacity | Remarks | Articls | Sumber” | Dasertption Artieis 7 Surber (a) Expt. Pte _ Date Inspection: This should be made for every experiment performed, defects noted and corrected whensver possibl3. 1. Is thera sufficient o1] in the bearings? 2. Ars the brushes badly worn? Incorrectly sat? ‘Z Is commtator rough or pitted? | 4. Doas armatur? turn sasily? 5. Are all comoctions corract? 6. Ar3 couplings or b31¢22 conn2ctions properly made? _ 7. Is machine clear of toole and forsign particlss? 8. Rave your wiring inspect2d and OK'd by instructor 9. Do oil rings turn and provide sufficient lubrication after machine -is running? 10. Ars there any def2che, and any unusual noises in the machine after it is running? 11. Note here tha maximm and mirnimm curren? ratings cf all the field rheostats you used in the tast. No. | Make R28 istance Current Rating Sin anes abe ' Note defects hars: (Correct them, if pessibia) (b) #8-D0——«-—S—S—~S*«CSRATURIE, REACTION IN A COMPOUND GEITIRATOR rocedure: 1. This test should be made on the same generator used in #6-DC*. Use a low-range ammeter in the field circuit, a high-range ammeter | in the line, and a high-range voltmter across the armature terminals. 2. Start the genarator as per instructions in #1 & #2-DC, adjust the speed to the value used in #6-DC* and bring up the armature terminal voltage until it equals the no-load (shunt field) value of #6-DC*. 3. Avoply a load and check the serics field connections. 4. Keeping the sveed and the field current constant throughout the test, tak3 simultancous readings of the armature terminal voltag?, lin2 current, fisld currsnt, and spssd zero output and for increasing values of load. 5. Datermins the armature resistance by the voltage-drop method of #2-DC, calculate ths total armatur3 and brush-contact RI drops, and hence, the voltag2 drops dus to armatures reaction. Data: Tabulate all observations on a standard data sheet. Curves: On a standard curve sheet plot four curves, using line currents as abscissae in each case, and as ordinates: , (1) the observed armature terminal volts. (3) the total volts develonei (armature terminal volts plus armature and brush-contact RI drops). (3) the saturation curvs voltages obtained in #6-DC due to the seriss fisld.* (4) the voltaze drons dus to armature reaction (the voltace differances betwsin curves (3) and (2). Follow instructions given in the gensral dirsctions. Questions: Answers to quastions 1-2 inclusive should 53 approved bfors starting the tast, the remainder to 52 answered in the final reports. 1. Define armatur? reaction. Explain the cross-nagnotizing 2ff 04; the demagnetizing effact. * In case the zonerator used in #6-DC ie not available the part of #6-DC necessary to give the required data should be repeated. (c) #a-no Quastions contd, 2. Explain tho function of th3 armature reaction curva. Describe briefly ths mathod of obtaining it. 3. Explain ths effect of armaturs raaction on commutation. 4. Hew can its effect be overcom3 on non-intscrpole machines? 5. How do interpoles affect the armature reaction? References: $8. &T. pp. 3-6, 40-41, 54-56. Langsdorf Art. 90-102, 162-163. Gray pp. 65, 67-69, 162-163. Smith pp. 54-63. Fr. & E. pp. 151-164. Pender pp- 77, 116-144. Dawes pp. 267-276. Karapetoff pp. 441-446 (4) DATA SHEET Station "Armature Reaction MPld. | Speed[ arm Line Tarm f Arm 1 Brush Total | Arm. | amp. : Const.| Term. ; Amp. jRes. ‘RI Drop ' Contact | RI Drop ' Reaction ¢ @ #Volts i¢ Ohms | Volts | Yolts | Volts | Volts A B C=AR D F=0-+0D i Armature Resistance (Lap Winding) _l 4 3 c=B/A D E4070" Amp. | Volts Res. No. True Res. # bid Onms Poles ‘ Ohms t AY. Armatura Resistance (Wave Windinz) Amp. Volts i Res. a. Ohms - Ay! Approved (e) Expt.# | Title: Date Diagram of Connections: Sketch neatly with pencil on a graph sheet the connections as actually used in experiment. Apparatus: Note name plate data of all machines used: Station € Mame Meke Number Type Form 3 Volts |Armperes | K.W. H.P. | Frequency Sp3ad Phase Instruments: Nota make, mumbor, etc., of all meters, inetrumimts, and miscellanccus equiomsnt used. - Meter, Make | Nuxber | Modal | Type | Ranga | Capacity Remarks oe i ‘ f pee ad Articlé | umber T"Deserfntion Artjeis”* Samer “) Doseriefion | (a) Titla | | Date Inspection: This should he made for every experimont performed, defects 8. 9. 10. li. Nota dsfeets hers: (Corrsct thom, if posseidiea) Have your wiring inepsctid and OF 'd by inetructor noved and cormrecte. whenever possibla. Is there sufficient of] in the veacinga? Are the brushes tbedly wort Incorrectly set? Is cemmitator rough or pitted? Doas arvatur? tun sasily? Are all connections eorract? Ars couplings or b3]1¢24 connections proporly mad3? . Is machine clear of tools and forsign particles?__ Do oi] rings turn and vrovide sufficient lubrication after machina 49 romuing? Ars there any defects, and any unusual noisse in she machine after it is ramning?_ ve Note here the mazimm and minim current ratings of all the field rheostats vou usod in the test. No. | Make Rasistancs Gurrant Rating ix. ihre 4 (bo) a Oo #9~-DC ‘ SPEED REGULATION OF A SHUNT MOTOR Procedure! 1. Use a low-range anmeter in the field circuit, a high-range ammeter in the armature circuit, and a hich-ranee voltm2ter across the armature terminals. 2. Start the motor by closing the line switch, gradually in- serting the plates of the water rheostat, and after the motor is up to speed, short circuiting thse water rheostat. 3. Adjust the position of the brushes to the neutral point, and take simultaneous readings of the field current, armature current, armature voltage, and spesd, for zero output and for increasing outputs up to a value corresponding to the rated full-load current input of the motor. ; ; - 4 At no-load, shift ths brushes a short distance to and fro about the commutator, noting the variations in sp3ed. Do not permit excessive . Sparking. 5. At no-load and with brushes in tha neutral position, i:creass the resistance in the field rh30stat and note the changes in speed for a s3riss of values of fisld currsnt. Do not permit the speed to become excessive. 6. At no-load, vary the 6.m.f. at the armature terminals by means of a variable resistance in the armature circuit and note the speed for a series of values of armature voltage. 7. Determine the armature resistance by the voltage drop method of #2-DC, calculate the total armature and brush-contact RI drops, and, hence, the counter s.m.fs. of the motor. Data: Tabulate all observations on a standard data sheet. Curves: Plot four curves on a standard shset, betwen: (1) speeds as ordinates and armatur? currents as abscissse. (2) n " " tt " volts " tt (3) n " " " field currents it " (4) omfs. as " armature currents " Follow instructions given in the general directions. (a) #9-DC Procedures contd. Questions: Answers to questions 1-4 inclusive should be approved hefore starting the test, the remainder to be answered in the final report. i. What is the function of a starting box? The over~load release? ‘The no-voltags release? : es ‘What factor aids the starting resistance as soon as the armature begins turning? 3. State two methods for reversing the direction of rotation of a shunt motor. 4. Why should the fisld rhsostat be cut out before starting a motor? Will a shunt motor start without a field current? What happens if the field circuit is opsned when the motor is running light? Whon loaded? Why? Is it good practice to place a switch in a motor field circuit? Why? 5. Define the speed regulation of a motor. 6. Discuss the effect of line resistance upon the speed regulation. 7. How will heating affect ths spesd of a shunt motor? State two effects. Which is greater? Are they additive or subtractive? Explain fully. . 8. What other method of speed control is used besides those yOu studied? 9. Give two reasons why the speed of a motor changes when the brushes are shifted. 10. What effect has armatura reaction on the spéed of a moter? ll. What is ths counter e.mf. of a motor? Explain its production and show how it automatically adjusts the current to the power demand. 12. Why will a motor spark badly with a weak field and heavy armature current? What remediss have been devised? (4) g2-DO Procedure contd. 8. &@. pp. 3-6, 59~70. Langsdorf Art. 127, 129, 132-134. Gray po. 80-83, 87, 91, 105-121, 371. Smith pp. 112-133. RP. & Art. 55-59, Franklin yp. 19-22, 32-35. 8. & F. pp. 106-111, 208-219. Morecroft pp. d2-39, 45-52. A.I.U.E. Definitions Std. Hdbk. Definitions in Standardization Rules Section. Pender pp. 202, 222, 293. Dawes pp. 339-343. Rarapetorf pp. 347-359, 699-715. (e) 38 #9-DC DATA SHEET Station Effect of Loading F14. | Arm |Total |Line Watts |Arm. Arm ; Brush !Total (Counter | Speed Amp.jAmp.| Line {Volts | Input Res. [RI Drop} Cm. DpiRI Drop jz.M.F. id 1# jam. [# Ohms | Volts} Volts ,Volts [Volts # “ae Te: . “Br = BC £48 D BCD GB . E_. T=G +H kK — . , L Armature Resistance (Lap Windi A B C=B/A D mw=4C /D¢ Amp. Volts Res. No. True Res. t | Ohms Poles Ohms Ave Armature Resistance Effect of Brush Shifting* (Wave Winding) Speeds + Am. Volts Res. With Rot- Against # # Ohms ation. | Nevtrel | poration “AV Field Flux** Effect of Changing Effect of Changing Impressed Armature Voltage Fid. Amp t # Speed Arm. Volts # Speed. id * Do not permit excessive svarking ee ON Ott tt tt speed. (f) Approved Diseram of Cornec ons: Title: Date Ske beh: n Apparatus: : Station # vey 4 44 7 Penis & gravh sheet the Note name plate data of all machines used; aed in experiment. Mies neck ne ie oko ' ___Murbe > Tipe - ; i free san ae fa = eageatiy tsee en — i 4 Lew soe cates a — — “| | _Vouss arnerss | Kale ae. Frequency Sprsd Phas pee Oi ene e emer net mays. seer se Se mae ets Ce aed an i a F in. wommed. Inetrumeats: Noto make, nunbar, etc. , of all meters, instrumants, and wmiecelinnucus equ Loms Brit "usad. fet or “rT hee , Melee | ivapsr i Medel | Type Remarks + wena emrnints degen ws emerdl ‘alia Sos ne al Ar’ its Trump ar escriotion arfiela ° Thaker Dssers se Pen Sania 4 t Yer mens naan Spence oo ae (a) Senne amet aR it Kester matte ten tene i Expt.__—_sTtle | | _._Date Inspection: This should be made for every experiment performed, defects noted and corrected whenever possibls. 1. Is there sufficient oil in the bearings? | 2. Are the brushes badly worn? Incorrectly s2¢7 3. Is commtator rough or pitted?_ 4. Doss armatur? turn aasily? 5. Are all connections corract? & Are couplings or bslted connsctions properly made? 7. Is machine claar of tools and forsign particles? 8. Hay> your wiring inspectid and OV 'd by instructor 9. Do cil rings turn and provide sufficiant ivbrication after machine 4s running? 10. Ars there any deftcts, and any unusual noiees in the machine after it is runing? 11. Note here ths maximum and minimum currart ratings of all the field rheocstats you usad in the test. No. | Make Resistance Current Rat ing Note defects hare: (Correct them, if possible) (b) 33 #L0-DC tts SFFICTIENCY OF A SHUNT MOTOR BY THE STRAY POWER L@THOD Procedure: 1. Use a low-range ammeter in the fisld circuit, a high-range ammeter in ths armaturs circuit, and a high-rangco voltmeter. &. Start the motor as in #9-DC and take simultaneous readings of the speed, line voltage, field current and armature current for zero output and for increasing outputs up to a value corresponding to the ratei full-load current input. $ Run the motor without load at the speed and field current values corresponding to those obtained under (2), and take simultansous readings of speed, armature curront, field current, lines voltage and armature terminal voltage. Speed adjustment is obtained by means of the water rheostat in the armature circuit. Field curront is adjusted with the fisld rheostat. 4. Determine the armatur? resistance by the voltage drop method of #e-DC, and hence, calculates the armature copper lossas. Data: Tabulate all observations on a standard data sheot. Curves: On a standard curve she2t+ plot nine (9) curves using watts output as abscissas and as ordinatas: (1) watts lost in the motor field. (2) watts lost in the field plus watts lost in stray power. (3) watts field loss plus watts stray power plus armaturs watts loss. (4) watts input (total losses plus output) (5) speed. (6) percent efficiency. (7) percent efficiency plus percent of input lost in stray power. (8) psrcent efficiency plus porcent stray power plus percent input lost in the armatures. (9) percent efficiency plus percent stray power plus pozcant armature loss plus psreent fisld loss. Indicate the various losses in each cage. Follow instructions given in the gensral directions. (c) 49 #19~D6 Procedure contd. Questions: wd se apnroved before Answers to questions 1-3 inclusiva sao startins the test, the remainder to »e answered in the final renort. 1. Give three expressions for the commercial efficiency of a dyname in terms of wetts input, vatts output and watts lost g- Give a tabular classification of all sources of loss ina TAINS « Indicate whether they ars constant or how dependent upon swe 83 or load, in ths cas3 cf a shunt motor. 3. What losses ars included under stray power? Are thess con~ stant for all loads and speeds? Why? 4. Why is the method used in this test particularly usoful for very largo shunt machines? 5. In the cass of a machine having 80% in determining tho lesses would give #% error in What with 90% efficiency? officieney, what error the officiencyT ~ 6. At what temosrature should efficianey de calevlated? References: 5S. &T. pp. 3-6, 74-80, Langesdorf Art. 170-180. Gray Art. 105~112. Smith Chap. X & XI B & pp. 127-132, 148-143. S. & F. pp. 258-265. A.I.E.E. 420-455. Std. Hdbk. Sse. 24, 420-455. Morecrofs pp. 538--59. Karapetort pp. 391-419, Pender pe. 2, 251-282. Dawe op. 346-35¢. hk. & T. pe. 141-146. £10-pe 41 (e) “DATA SHEET Station Motor Running Under Load A iB C D E FS T Line Fld. Arm. { Total Arm | Brush | Watts | Watts R.P.M.| Volts Arp. Amp. Amp. Res. |Con.Drp.; Lost Lost # Fd _ LF # i Ohms | Volts . | Field C+D ED“+-GD BC 1 ai ek | t | im | WN _: zl Stray | total | Watts | Watts 4 +4 Input! SInput| Ghost (Total % Power | Losses | Input jOvtput | Eff. (Lost In iLost In] In StrayInput Loss | Watts Arm. | Fld. | Power | =100 | Herd [ BET L-K (1OOM/E {100H/L [100 1/L | 100 J/LjN+O1P+9 { Motor Ruaning Light A ic is [f@ U F et vj Ww Xx XY I Fid.jArm.!Line (Arm. jArm. Brush |Watts Watts Total Total iStray pee : Volts|Res. | Drop {Lost [Lost |Copper jWatts (Power i i # Qhms_ | Volts!Arm (Fld. jLosses |Input {Loss FS4GS CT | V+W (Crisu ly-x + - Armature Resistance i Armature Resistarcs ~! (Lay Winding) . i (lave Winding} A 3B C=B/A D | z=40/D° i Amp. Yolts : Res. Amp. | Volts | Res. No. |Trua Res. | # a | Ohms i A ole Ohms (Poles Ohins es | i { eT aaa AY: coe Approved Tate Diagram cf Connections: Sketch neatly with nen cil on a graph sheet the cemneetions as a ct ally used in experiment. A#poaratus; Note name plate data of all machines used: Station # Name Maks Nurber Type Forma 4 Volts | Ammeres KW. of 00 OUT. Frequency | Sraed Phass i : + Instruments; Note make, number, etc., of all meters, inetryummts, and miscellanceus squipmsnt used. y ms co; : i <n anna > = : a : ~ i rere “ 4 ms ™| Meter, Maks 1 Nusber | Model rype Range Capacity Romarks i . od. ee ee ae ae 5. renee ‘ <n os T E : a aia tee eer eee remem ea > a“ Article Sanbsr 7 Diserint fon ond : iy ve pene + + : i i i J apres a prewe wn cate ney ce eo ssenpeerniener pict pent ot _ Expt. Title Date Inspection: This should be made for every experiment performed, defects noted and corrected whenever possibdls. al. Ts there sufficient oil in ths bearings? 2. Are the brushes badly worn? Incorrectly sot? 3, Is commtator rough or pitted? 4. Poss armatur? turn sasily? §. Are all connsctions corract? 6. Arz couplings or belted connections propsrly made? 7. Is machina clear of tools and forsign particiss?_ oo 8. Hav2 your wiring inspacted and Of'd by instructor 9. Do oll rings tum and provide suffici2nt lubrication after maching 4s running? 10.. Ars thore any defects, and any unusval noieza in the machine after it is rmoming? 11. Note here ths maxiom and mininmun current ratings of all the field rheostats you used in the jest. No. | Make Rasistance Current Rating Note defects here: (Correct them, if possibie) (bo) 42 F.L-DC SPEED REGULATION OF A COMPOUND MOTOR Procedure: 1. Use a low-rang? ammeter in the field circuit, a high-range ammeter in the armature circuit, ani a nizh-rangs voltmeter. 2. Start the motor with the series field discornected and ammeters short-circuited. After it is up to spes Fl closs the saries ficld switch first, then open the switch in the shim around the serios field. 3. Keeping the applied voltage constant, take simmltancous readings of field current, armatures current, line voltage, and speed, for zero output and for increasing ourputs = to @ valus corresponding to the ratod fuil-loai current input. £ the sposd of the motor remains constant or increases with load increas:;, “ths motor is connected differentially, oth3rwis2 it is connected cumulatively. 4. Rapsat (3) after reversing ths soriss fi2ld connections. Data: Tabulat: all cbhssrvations on a standard data shoot. Curves: Plot curves on the same standard sheet between watts input as aoscissae and speeds as ordinates for both the differontial and the cumulative connections. Follow instructions givon in the general directions. Questions: _ Answers to qu3stions 1-3 inclusiv3 should »¢ approved befors start- ing the test, the romaindsr to be answered in ths final report. 1. State and explain ths differance in the starting characteristics of a differential compound and a cumulativ> compound motor. “What can be done to improve the starting charrctoristic of the former? 2. Power is applisd to the pulley of a cumulative compound motor witil it is driven abov2 normal no-load spe2d. Doss it oporats as a cumulative generator? Why? 3. State some of the applications of cumilative and differontisl motors. (e) #11--DC Questions contd. 4. Why does the differential motor spark on overload and the cumulative motor as a rule not spark? 5. Uxplain any difficulties encountered in the operation of the differential motor. Also state and e-mlain the remedy. 6. Can a constant spesd for all loads b2 maintained by differential compouysding? Why? . 7, Calculate the percent soeed regulation from your data. 8. How could the number of seriss turns neceisary to give zero spsed regulation b3 obtained experimentally? References: S.&T. pe. 3-6, 81-82. Langsdorf Art. 151-133. Smith pp. 154-1606. F. & te. Art. 60. S. & F. pp: 238-239. Karanstorf pp. 374-377. Pendar pp- 59, 199, 212-214, 202, 222, 293. Dawes p-. 328. (4) #11 pe Station: DATA SHEET Differential Motor Spesd Regulation Fid. Arm. Total Line Watts Speed Amp. Amp. Line Volts Input # a + __|# Cumulative Motor Speed Regulation Fld Arm. Total Line Watts Arm. | Amp. Line Volts Speed A 3 C=A+B 3D E=CD (6) Aporoved: 44 Exvt. ¢ Title: Date Diagram of Connections: Sketch neatly with pencil on a granh sheet th comectiois as a tuclly used in exneriment. Epoaraius:; Note name plete data of all machines used: Station # Vawes Mt Fa aespthn oy we " <1 " {ems | eke 5 Nurber Taye Form 4 Po Wolts K.ve { H.P. . Frequency Soaed Phase en aegare po MN cep ee ~ ‘seins eee = aye ramen anna nat” ne Inetrumeuta; Nots make, numbar, etc., of all meters, instrumants, and miscelle Anse ne equipment "usod. | uetar; Make | Nucbor [Model | Tyoe | Henge | Capacity [| Remarke Ar*icis | thambar | Daseription Articils csker a ~ wean ee { wep we atamen, ode inany wad (a) Exot. Title | Date Inspsction: This should he made for every experiment performed, defects l. as noted ard corrected whenever possibls. Is thers sufficient oil in the bearings? | Are ths brushes bedly worn? Incorrectly set? Ts commutator rough or pitted?__ Doss armatur? turn sesily? Are all conmnsctions corract? Ar2 couplings or 63124 connections properly made? : Is machina clear of toole and foreign particles? Hev2 your wiring inspsct ad and OK'd by instrector Do o11 rings turn and provide sufficient lubrication after machina ‘4s running? Are thore any defzcts, and any unusual noises in the machine after it is running? Se eed Note here ths maximum and minimum currant ratings cf all the field rheostats you ug3d in the tes%. , No. | Make Rasistance Current Rativg. Qazs MAX. iin. Notes defects hers: (Correct them, if pessibie) (») | 45 #1S=DC OPERATION OF SHUNT GENSRATORS IN PARALLEL Procedure: 1. Use low-range ammeters in tne field circuits, high~range ammeters in the lines, and a high~range voltmeter. 2 Bring each generator w to its proper speed, all line and field switches being open, and ammeters short-circuited. 3. Close the field switches and adjust the field rheostats of the generator until the voltaze of each is equal to its normal rated valus. 4. With the voltmeter, chsck the polarities of switches 5, and So- If theso are correct, proceed with (5), otherwiss correct the polarity by making the proper changes in connections, 5. Close switches S,; and L and apnly normal load to generator #1. 6. Check polarities of ths bus bars and generator #2, and adjust the voltage of generator #2 until it is aqual to that of the bus bars. 7. Close switch So+ and nots ths voltage across tho open switch S,-. If tho voltmeter reads zero, or vory nearly so, switch So- may be ctosed and ths two machines are paralleled. 8. Adjust the field rheostats of both generators, inserting resistance in #1 field circuit, and taking it out of #2 circuit, keeping the bus-vdar voltages constant, and at the same time shifting part of the load from g2nerator #1 to gensrator #2, until they divide the load in provortion to their rated outputs. This will be indicated by the respective ammeters. 9. Shift all the load from generator #1 to generator #2 by fisld rhéeostat adjustment as in (8), then open switches S,+ Repeat the operation of paralleling several times. 10. Parallel the generators, then decrease the field strength of generator #1 until it is seen to be operating as a motor taking power from generator #2. This will be the case when its ammeter indicates in a negative sense. 11. Adjust the field rheostats until generator #1 takes all the load and generator #2 runs as a motor. 12. With no-load on either generator, comnect them in parallel, and keeping the spesds of each constant, increase the current in uniform steps, until full load for the two machines is obtained. Keep the e.mf. of the system constant, and current equally divided hetwen the two machines. Record the data. (c) 46 #12-DC Procedurs contd. Tabulate all observations on = standard data sheet. Questions: Answers to questions 1~6 inclusive should 2¢ approved befors start- ing the test, ta? romainder to be anewared in tho final raport. 1. Why are gonerators operatid in parallel? 2. With a leaded shunt generator and an unloaded one, give full dirsctions for putting the lattsr in parallel with the former, and causing thom to shara the load as dasir2d, without changing the voltage of the load, 3. Giv3 dirsctions for removing a loaded generator from parrllsl operation with others. 4. What will oceur if the fisld current of a machine running in parallel is reduced oeyord the voint whera it takes zero load. Explain. - What will oecur if the nositive terminal of one generator is conmmected tc th2 negative terminal of thse other? 6. What will occur if a field circuit is opened whils the machine is in para llel with others? 7. What must of trus of the characteristics of two shunt generators in order that they will automatically share all loads equally when paralleled? 8. What must 3 trus of ths characteristic of gen3rators of un- equal capacities in order that they will automatically shar? all londs pronortionally? (4) #12-DC Questions contd. any 9. If apair of shunt gensrators do not properly share tho load, wat must bs dons to one of thse generators, and to which ono? Aofarences: pp. 3-6, 94-98. Lanssdorf Art. 122. Grey - Art. 191-197. Smith pp. 109-110. ¥. & &E. Art. 85, 87. Franklin pp. 123-1235. Panésr om. 185. Dares D. 272. Karan tort p. 325. R. & T. D. 94. (e) #2-00 (f) Station Gonsretor #1 A 5 C i D Ly F EMP. mate Fld. , Arr Speed K.W. Amp. Amp. ; Amp. Output. # # # ; B+ # BS) ; Generator #2 Totals Amp. Am. Arp. Output Amp. Output 4 + G-+-H t AG B+G. FIK | G i I Bi K i M i Exp: # Title: Date Diazram of Connections: Sketch neatly with rencil on a graph sheet the connections as actually used in experiment, Apparatus; Note name plate data of all machines used: Station # 2 | ame | Make Number Lyps Form _ Volt Arpares K.W, g.?, Frequency | Spaed _ Phases instruments: Wote maks, number, ete., of all meters, insteummnts, and @ikcellancous squlpmant used. Meter, Make | Nucber |Mcdol T Tyna | Range | Capacity | Remarks a i : : bi i Articls | Wambar” Teserint ton Articrs (a) Expt, Title | Date Inspection: This should be made for every experiment performed, defects noted and corrected whenever possibls. 1. Is there sufficient oil] in the bearings?_ 2s Are the brushes badly worn? Incorrectly set? Z. _ Is commtator rough or pitted? | 4. Doss armatura tum sasily? 5. Are all connections corract? 6. Ars couplings or b31t24 connsctions properly mads? 7. Is machine clear of tools and forsign particlas?__ 8. Havo your wiring inspect 2d and OK'd by inetructor 9. Do oil rings turn and provide sufficient lubrication after machina 368 running? 10. <Ars there any def3ctg, and any unusval noiase in the machine after it is running? ii. Note here the maximm and minimum currant ratings of all the field rheostats you ugad in the test. No. | Maice Rasistance Current Rating ; Qams iex. iin. Note defects here: (Correct them, if possible) (bo) #13-DC OPERATION OF COMPOUND GENFRATORS IN PARALLEL Procedure: 1. Use low-range amneters in the field circuits, high-ranze ammeters in the equalizer and lines, and high~-rancs voltmeter. a : @ Bring each generator up to its proper snesd, all line and field switches being open, and amzstors short-circuited. 3. Close the field switches and adjust the field rheostats of the generators until tho voltage of cach is 2qual to the normal rated value. _ 4 With the voltmeter, check the polarities of switches S, and So» If these aro correct, proceed with (5), otherwise correct the polarity by making the vropsr change in cormmactions. @ 5. Adjust the voltags of gonsrator #1 to normal value, anniv full load, after closing switches S;+ , S.- , and L, and note ths full load voltage. If this is lass than no-load voltags your ssries field is Lv 3z read. Remove the load, open the switches and corr:ct ths seritzs field connsetions if nacessary. 6. Riprat (6) on sonerator #2, If the chang: in voltage from no-load to fuli-leoad (volta 7 eoeed ation) is the samo for 2ach machine, processed with (8), othervis? with (7). 7. <Across th scries field of tho generator showing the greater chang? in voltage botwien no-load and full-load, conn3ct a shunt lead which will divert 2nough current from the seriss field to make the voltage ragulation of this eansrator squal to that of the other. Tha total, resistance of the series fislds and their siumts should also bo such that they ars resoxoctively inversely proportional to the full-load current outputs of the rospactive generators. This adjustmant is called compounding and is nocossary to insure successful paralleline. 8. Close switenss $,-+, Sy- , and L, and apply normal load + generator #1. 9. Close the equalizer switch?s Syt and Sjt , and also $,-+, and adjust the voltage of g2nerator 43 until it is aqual so that of the sus bars. 10. Note ths voltage across So-- If ¢ voltmeter roads gore or no wa very nearly so, switch 5o- may b2 closed and tha two machints ars paralleled. (ce) 59 #13-DC Procedur? contd. ll. Adjust ths field rhsostats of both generators, inserting resistance in #1 field circuit, and tazing it ont of 42 circuit, ksop- ing ths bus-bar volteg3s constant, and at the same time shifting part of th: load from generator #1 to gonerator #2, wmtil they divide the load.in preportion to their rated outputs. This will be indicatad by ths respectiv> anmeters. - ig. Shift ail the load from gensrator #1 to gonerator #2 by fisld rhsostat adjustment as in (11), then open switch Sy-, and after this switches Syt and Sot Ropeat the operation of paralicling several times. 13. With no-load on either gonsrator, connect them in parallel, and keeping the sp23ds of each constant, increase the current in uniform steps until full-lord for the two machines ig obtained, Keep the o.mf. of the system constant, and current equaliy divided botwoen the two machines. Record the data. Data: Tabulate all cbsarvations on a standard data shoct. Questions; Answers to questions 1-5 inclusive should bs approved before starting ths test, th? ramaindsr to bs answered in ths final raport. 1. Explain the action of two compound generators in parallel without an equalizer. How dogs tho equealizsr operate to make satisfactory parellel running possibl2? Discuss fully. 2. Explain. how diffsrances in ths over-compounding of two machines affects the division of load betwaan them 3. Why should the equalizer circuit be as short as possible? Why of larg: cross-saction? What is ths effect of resistance in the equalizer circuit? 4. Show how the seriss coil resistance must >a related to th capacity of the machines, in order to give proper division of icad and just what happens if this relation does not hold. In such ¢ how may proper automatic division of load b2 obtained? Why can a shunt around ths sarizs field 53 used for this adjustment and what would be the fumction of such a shunt? (a) 51 #LS-DC Qurstions Contd. 5 Deseribe and explain the operation of throwing an wloaded generator in parallel with a leaded one, and dividing the load. Also of relieving the machine of the load and disconnecting it. 6. Compound generators sometimes have their series fields connect- ed continuously to the squaliger and one of the other bus-bars. What is the effect on ths action of a generator in operation when the series field of a dcoad machina is so connected? 7. Why should no circuit breaker or fuss be put in the equalizer circuit? 8. Why should no singl2-pols circuit breaker se put betwean the serias coil and the bus tars? 9. If a flat-compound generatcr and a shunt generator are paralleled at References: “no lead how will they share a lead?» Explain using curves. * 5. &T. pp. 3-6, 98-103. Langsdorf Art. 122. Gray Art. 191-197. Smith po. 110. Fr. &.E. Art. 86-87. acanklin, pp. 125~128. Moracrofs pp. 79-84. Pender pp. 57, 152, 171, 176, 185. Dawes pp. 295-299, 374. Karap2toff pp. 317-329. R. & T. pp. 88, 98. (a) 213-DC DATA SHEET Station: Gen3rator #1 A 3B C ‘Dd F ¥F G Exte Fid. Arm. mew. Equalizer EMF. | Amp. Am. Arp. |R.P.M. (Output Arp. ry 4 # BIC # 48 $ Gonsrator #2 Totals E Ig J K L M N Ext. Fld. ATH. | KW. | Load KW, Amp. Amp. Am. | R.P.M. Output Amp. - Outout # tt H+I a AE B-H F-L (f) Approved _ os aN sed sic tn bo! pe fe t ‘ er Gacy es ae es i fo ted aah AC { bos ae a ~ ak = eae snd AC > “mn ska 053 te ft O69 2 fet pet ft beat tar pit pet oO ' fe Cc C bat tt CO ~% | CQ be O-AC OLAS 22— AG oR AN Ae lee ne g4-L0 ALTERNATING CUSRENT LABORATORY EXPERIMENTS Alternator Field Compounding. ixternal Characteristic of an Alternator with Non-inductive TOc.d. External Characteristic of an Alternator at Constant Power Wachor. Alternator, Open-circuit Saturati and Synehronsus Tmmedance Tests. Alternator, Yero-Power-Wactor Saturation Test. Alterdator Short-Circult end Open-Circuit Core Loss Tests. Pavaliel Oosretion of e Alt: srnators. synehronovs Motor Y-Curv3s. Synchronous Motor Current and Powsr-~Tactor Curves. Prvicdoney of Rotary Converter. otery Converter, Raletion between Field Currant & D.C.Volts. 23-wire Gsnsrator with Unbalanced Loads. former, Ratio and Polarity. Trans?e rmer Resistance, and Cor: Loss T3sts. Transvormer Copper Losses, Impsdance and R2gulation. Watt-nou’ Mater Calibration. Boost and Lower Test on Induction Regulator. Curve Tracing wita the Oscillograph. Transformer Connections (a) Three-phas3: Cornsetions with Two Transformers. (>) Three to Two-phas2 Transforzation. (c) Twe to Six-phas? Transformution. Transformer Connaictious - ¥Y delta and delta-Y. Eprect of Unbalancing in Polyphase Transformer Banks. Sigh Tension Transformer Tasts _ Indvetion Motor Pasts (a) Ruming Lisht Saturation. (o) Locked Saturation. (c) Circle Diagram @ Charactsristic Curves.: (d) Efficiarcy Determination by Prony Brake. Thormionic Vacuum Tube Characteristics. av re: aE S| A.T.U.E. Collins Desir 3 6 i 3 @ Q od ; oo wD . aw G 2 oY a ct ° cr ot Do ¢ oO MM ee tf ef oad teh bet tat @ ws i, Phe at Re 8 . Gray G.E. Rev. Hey ccur.Elect. Karanetoft Lanzedorf Layrencs Magnusson Mtr.Hdbk. Rk. & T. 5S. & F. fo Ss. & a. ae th. ta. Hab. Stoke ct Thomalan Thomson Wastinghors. Weston RETSRENCES Stanger eration Rul.os of th? American Institute of nComnare ial Blocteicsl Testing." "Electrical Tnzinzeriag" Yol.II. Alternating Currents "Industrial Fleatrical Msasuring Instruments". "Electric Journal". "Factory Testing" "Pocket Bock" "Dynamo Laboratory Manval" Vol.I, Franklin & Esty. "Blemants of Flectricai Engines ring", Vol. I, II, Franklin & Esty. . "Principles & Practise of Electrical Ungineering" "general Blectric Review" NAlternating Currents "Journal of Electricitv, Power & Gas" WE xpe: rimental Rlectric Engineering" Vol.I (3rd edition) Vol.II(and edition) "Principlas of Direct Current Machines" "Principles of Alternating Current Machinery". "Alternating Currenis® Wleterman's Handbook Wliectrical Engine2ring Laboratory Experimmntst Ficksr & Tucker. wlesting of Flectro-Magnatic Machinery" Swenson & Franien?isid. tZaboratory & Factory Tests in Nlectrical Engineering" Sever & Towns ond. "Practical Alternating Currents" Standard Handboo’ for Electrical Engineers" caper atical Elements cf Elactrical Enginesring" faxtbook of Hlectrical tnginesring" 2nd Sdition, 1910. " Dynamo-Rlectric Machinery" “Instructicn Books" "Instruction Books" Expt. 4 Title: Date Diagram of Connections: Sketch neatly with pencil on a graph sheet the connections as actually used in experiment. Apparatus: Note name plate data of all machines used: Name | Maks {| Number Type Form J oom Volts | Amperes KW. | ¥.P. | Frequency Snaad Phases Instruments: Note make, number, etc., of all meters, instruments, and miscellantous squipmant used. Meter; Make Number | Medel Typs | Range Capacity ' Romarks die of i : . dm sere al j Article Numoer Isscriction | Articlo | in ‘ i Penne 7 iene & ferme ee steerer eek ce ne ae mee te \ (a) Lot. Title Date Inspection: This should be made for every experiment performed, defects noted and corrected whenever possibls. l. Is there sufficient oil in the bearings? 2. Are the brushes badly worn? Incorrectly set? 3. Is commtator rough or pitted? 4. Doss armatura turn aasily? 5. Are all connections corrsct? ' 6. Ara couplings or b3lted connsctions proporly mad2? 7. Is machine claar of tools and foreign particles? 8. Have your wiring inspectad and OK'd by instructor 9. Do oil rings turn and provide sufficient lubrication after machine is running? 10. Ars there any defects, and any unusual nois3s in the machine after ; it is ruming? 11. Note hers ths maxim and minimum current ratings of all the field rhsostats you used in the test. No. | Make Rasistance Current Rating ; Obms Max. i Min. i Note defects here: (Correct them, if possibls) (bo) 55 #1-AC = DETERMINATION OF EXCITATION RHQUIRTD TO MAINTAIN CONSTANT VOLTAGE ON AN ALTERNATOR (FIELD COMPOUNDING) Procedure: 1. Use a low-range DC ammeter, a high-range AC amuster and @ high-range AC voltm3ter. &. Run the AC generator three-phase at constant frequency or speed, and constant terminal voltage and takes readings of fisld and armatur3 currants, terminal voltage and speeds for a series of water- rnsostat loads ranging from zero to about 25% overload. Take six readings. 3. Repeat (2) using a single-phase load. 4. Repeat (2) using an induction~motor load. Data: Tabulate all observations on standard data sheet. Curves: Plot on the same standard sheet the field commounding curves from the data obtained. Use load currents as abscissae and field currants as ordinates. Follow instructions civen in the general directions. Questions: Answers to questions 1-4 inclusive should be approved hefore start- ing the test, the remainder to be answered in the final report. 1. What is tha nature of the loads in (2) and (4) of procedurs? 2 May compounding te resorted to in the cass of a generator? Why is it not generally ussd? 3. What method is usually used to ks3am the voltage of an altor- nator constant for varying loads? 4. What factors contribute to tha fall of potential of an alternat- or on non-inductiv2 load? On inductive load? 5. Compars th field compounding curves for ls *eeing and non- inductiv? loads. ; (ce) 56 #1-AC Qu2stions contd. 6. If the E.M.F. of tho 3xciting currant is 125 volts, what must bo the current and resistance ritine of the fisld rhoostat in order to miintain constant voltag? for tha readings you obtained? 7. What change would have to be made in the field rhsostat in order to maintain constant voltage with a load of leaiing powsr-factor? 8. _An alternator has the following characteristics: Field current required to nroducs 11C volts at no oloed, 2 amp. Field current required to nroduce 110 volts at full non-inductive loac, 3 amp., field currant to vroduce 110 volts at full load, 0.60 power factor, 4.5 amp. Field resistanca 50 ohms. Can constant voltage be maintained if the field is excited from 125 volt mains? What must b3 ths voltag> of th2 axciting civcuis? References: $.&T. po. 123-125. Magnusson pp. 211-220, 226-230. Gray Art. 259-263, 266, 268-271, 276. Fr. a& ER. Art. 1-9, 48-56. Smith pp. 189-184. Dawes pp. 99-171. Karapstoff PP. 532, Vol.I; po. 129-150, Vol.II. (4) 57 | #-AC DATA SHEP? Field Compounding Fla. Armature Armature Volts {Speed Remarks Amp. Amp. Const. Const. , od 2 3 Av] 1-2 (1-3 [8-3 i Av : 3-Gnon- inductive §$-G@non-induct ive 3-G inductive Approved _- (e) Expt. Diagram of Connections: Title: Date Anvaratus;: Station # Sketch neatly with pencil on a graph sheet the connections as actually used in experiment. Note nams plate data of all machines used: Name Make Number Type Form Volts | Ameres KW. | EF. Frequency Spead Phase Instruments: Note make, number, etc., of all meters, instrummts, and miscéllancous squipmant used. | Meter; Make Number | Model Types Rango Capacity Romarks Erticie | Number Sseription | " (a) bret. 9. 10. ll. section: Thi Title Date s should he made for every axneriment performed, defects noted and corrected whensver possible. q 2 Is there sufficient oil in th? beerings? Arc the brushes badly worn? Incorrectly s2t? Is commutator rough or pitted? Doss armatur? turn sasily? Ars all connections corract? Ars couplings or valted connections pronorly made? Is machine clear of tools and forcign particles?__ Have your wiring inspected and OM'd by instructor Do oil rings turn and provide sufficient lubrication after machine *s ronning? Ar? there any deftcts, and any unusual nois3s in the machine after it is rumins?__ Note here the mexirum and minirum curremt ratings of all the fisid rhaostats you used in the tast. Gurre.t Rating No. | Make , Max. Min. Note defects hera: (Correct them, if possible) (b) #2-AC EXTERNAL CHARACTERISTIC OF AN ALTERNATOR WITH NON-INDUCTIVE LOAD Tata taken in this test is used in #3-AC and should be preserved. 1. Use a low-rang? DC ammeter, a high-range AC ammeter and a high-rangs AC voltmeter. 2. Run the alternator single-phase at a frequency of 60 cycles and rated no-load voltage. Xeeping th: field current constant, note tne terminal voltages for a series of water-rhoostat loads ranging from zero to 25% overload. Take six readings. 3. Repaat (2) runing the alternator at 50 cycles and rated no- load voltags. 4. Repzat (2) using the same normal excitation but at a constant frequency 506 balow normal, or as low as possible. 5. Repeat (2) running the alternator at rated fraquency but with excitation 50% oelow normal. Data: ee Tabvilate all observations on a standard data sh33t. Curves: Plot on the same standard sheet the external characteristic curves from the data obtained, using load currents as ahscissas and voltage as ordinates. Follow instructions given in the general directions. Questions: Answers to questions 1-4 inclusive should be apvroved before start-~ ing the test, the remainder to be answered in the final report. 1. What is the relation »stwsen frequaney and spesd of an alter.uater? 2. What factors contributs to ths drow in voltags of an alternator at non-inductiv2 load? 3. How does the current in an armature conductor of a DC generator vary with respect to time? (c) 53 #2-AC Questions contd. 4. How doss tha current in an artatur3s conductor of an alternator vary with respect to tims? &. What is meant by reactanes of an alternator and upon what does it depend? 6. Why cannot ths total charact3ristic be sasily determined from the external in cas? of alternators? 7. Why is tho drop of voltaga in an alternator greater than in & saparat3iy excited direct current generator? 8. Why are alternators usually saparataly excited? References: Ss. &T. pp. 131-132. Magnusson pp. 216-226. Gray Art. 272-274. F.& EF. Art. 62-64. Smith po. 171-182. Dawes pp. 99-117. Karenetoff p. 332, Yol.I; po. 129-150, Vol.II. (a) HAC olga treme DATA SHEET Extornal Characteristic t Field Arm. Arm. Freq. Amp. Amp. Volts | Const. Remarks Const. |# ine 4 60 Cyulss 50 Cycles 50% rated freq. normal fld. 50% normal fld. rated freq. fe) Approved Pate Jigeram of Connections Sket e cenasctions Note name plate data of all machines used: ch neatly with pencil on a graph skeet the 3 at acttunily used in exneriment. Station # | lems | Make Number Type Fora 3 bee i 4 = 4 Volts jdeperes | RW. TEP. Frequency Saad Phase ‘ i er Instruments; Neto makc, numer, etc., ef all metars, instruments, and miscsilancous equipment used. Meter; Make | Nusber | Moisl | types | Ranga | Capacity | Romarks— ome + t { | oben J = 4 H t i . Articls Number “T Doseripsion Articla “hacber Descrintion | s : (a) burnt. Title Date netcod and correstel1 whensver possible. 1. Is there sufficient oil in the bearings? 2. Are the trushes badly worn? Incorrectly set? Z Is commatator rough or pitted? 4. Do3s armatur? turn sasily? 5. Are all connections correct? 6. Ara couplings or b3lte4 connactions properly mad27__ 7. Is machine clear of toole and forsign particles? 8. Hav3 your wiring inspact ad ane OF td by instructor 9. Do oil rings turn and vrovide sufficient lubrication after machina hs ronning?_ 10. Ars there any deftets, end any umusual nois2s in the machine after it is running? ll. Note here ths maxiarm and minimum currant ratings of all the field rheostats you used in tha test. No. j Make Rasistance Current Rating On". . Max. Vin. Note defects here: (Correct them, if possibie) (>) #3-AC EXTERNAL CHARACTERISTIC OF AN ALTER TATOR AT CONSTANT POWTR TACTOR Procedure: This experiment should be performed on the alternator used in #2-AC . * 1. Use two low-range DC ammeters, a high-range AC armeter, a high~ range AC voltmater, a power-factor indicator and a frequercy meter. 2. Connect the direct-current machines of each of two sets to operates as motors and the alternating current machines, one to operate as an alternator and the other as a synchronous motor. 3. With all the switches in the fisld circuits of the alternators and those on the dynamometer~board open, bring each set up to speed. 4, Close the field switch of the alternator and bring its voltage, as measured across ong phas3, up to riormal frequency and to the no~load value used in (3) of Exp't #2-AC. * Check and record the voltages across all phases. Notes and record the field current. This value should be maintained constant throughout the test. 5. Close the fisld switch of the synchronous motor, bring its speed wo to such a value that the synchronizing lamps become bright and dark slowly, and adjust the field rhsostat util ths voltage as measured across eech phase is equal to that across gach phass of the alternator. 6. If ail three synchronizing lamps become dark and bright simultansously, then the phase-rotation is correct and you may proceed with (7). If the lamps become dark and bright successively, or in rotation, then the phase-rotation is incorrect and two of the leads from one of the machines to the dynamometer board must be interchanged. 7. The lamps as connected sive the proper phase-rolation when they ars dark and if they become dark very slowly, thon the frequoncies of the two machines about to be connected togatiisr or synchronized are very nearly equal, and ths thras single-phase switech?s on the dynamonsctor board may b2 closed at the instant the lamms »scom? dark. After arc chronizing the two machin3s, the DC driving roter of the synehroncus motor set may b2 disconmmnoctad. 8. Check the powsr-factor moter for lsading or laggins currents as follows: Vary the synchronous motor fisld and observe tho effset on the reading of the AC ammeter. If the current is leading, increasing * In case ths alternator used in #2-AC is not availatlsa necessary to give the desirsd data should do repzated. S20 curve instructions on next page. (c) #5-AC Procedure contd. the fisld strength of the synchronous motor will increase the current, but if the current is lagging, it will decrease it. At wiity power- factor the current will bs a minima. The ammeter may be inserted into axy one of the three lines by msans of the dynamometer board. To do this, closes only ons of ths thr2s two-nols switch2s on the board and then open ths single-pole switch iumsdiately abov2 it. Te remove the amnever reverse the epsration, 1.3. clos3 the single-ncl? switch and ‘thon opan th? dowuble-pole switch. Novor close moro than on2 of the acubple-pole switehes at any ons tims. 9 Load tha altarnator througn ths synchronous motor, making the latter drives its DO machine as a gsnerator, and with ths pow2r-factor kept constant at 0.7 leading and alternator fisld current kept conetant at the valus obtained in (4), tal:e readings of the alternator ficld eurront end volt2z2, th2 synchronous motor fiz3ld current, ta? AC lin current, powsr-factor and froqvonevy for a serizs of five values from zero to fuil-load valu2 of the DG motor driving the alternator. Keep tha frequency, altarnator ficld currant and power-factor constant. 10. Repeat (9) for constant power-factors of 9.9 leading, and 0.9 and 0.7 lagging, keeping the alternator field current constant at the value used in (9). Vary the powsr-factor with the motor field. Tabvlate all observations on a standard data sheet. Curves: Plot, on the same standard sheet, the external characteristic curves for the various power-factcrs used in the test, line currents as abscissae and voltag3s as ordinates. Plot also on the sane sheet, the eur: for unity power-factor from the data obtained in (3) of #2-AC.* Follow instructions given in ths general dirsctions. Questions: Answers to questions 1-5 inclusive should be apyrovid aefore start- ing the test, the remainder to be answered in ths final «copors. 1. Define voltag?2 regulation of an alternator. Upon what factors will the regulation depend? * Ses note on preceding pages. (a) eS #3-AC Questions, Contd. 2. What is meant by the external characteristic of an alternator? 3. What is meant by synchronizing? 4. In synchronizing alternators, what conditions must the E.M.F. of the machines fulfill? . 5. What thrae things do synchronizing lams indicate and what ars the conditions under which the lamps give correct indications? 6. What is the effect of a lagging load on the external characters istic and why? 7. What is the effect of a leading load on the external charact2r- istic and why? 8 "xplain the effect of a lagzing and leading load on the kilowatt capacity of an alternator. 9. Is it possible to hava a negative regulation? Under what. conditions? 10. Is it possible to operate an alternator without any fiold exci- tation? With a negative? excitation? If so, mder what conditions?. References: Magnusson PD. 216200, 237-241, 245-246, 256. Gray Art. 374, 279, 2b4- 299. F. &k. Art. 62, 63, 68, 70-77. mith _ pp. 171-182. Dawes po. 99-171. Karapetofr p- 532, Vol.I; pp. 129-150, Vol.II. R. & T. pp. 227~+239. - (e) speaorddy { 5, S3BTL 0 2, S88'TE °9 2, Ppee'lso 4 2 yPe8TL-0; re: # ay {eS | 2 4 tp Avig-e)e-)e-T syrauey) -duyhysuopr 4ysuo09 # # Ppsuop € 3 “PLa] coed | *beag soleduy S4TOA ‘day | ‘day | s4Tor “en Mod “PLA ‘UAG | I04eUss4TV 1O7OH" OC) 2U0F3B9S OV-f# Expt. Title: _ Date Diagram of Connections: Sketch eatly with rencil on a graph sheet the comiections as actually used in experiment. Apnaratus; Note name plate data of all machines used: Station # [ams Make ‘Number Type Form “| Yoits (frneres | K.W. THUR. | Frequency Speed Phase } i Instrum meats: Neto makc, numbsr, etc., of all meters, instrumants, and miscellanscus equipment "asad. jeter) Make | Macber [Model | fyoe | Range | Capacity [Remarks in pense was meal a wr oe | Articls Number esceription Articls Sane OP Doserintion | he nin dea {a} Expt. Title | | Date Inspection: This should he made for every experiment performed, defects inspection ie 9 9. 10. ii. noted and corrected whenever possibls. Is there sufficiant o11 in the dbearinga? Are the brushes badly worn? Incorrectly set? ; Ie cemmtator rough er pitted? Doas armatur? turn sesily? -Are all cormections corract? Ar2 couplings or b31%322 connections proporly made? Is machine clear of toole and forsign particiss?__ Hav2 your wiring inspact3d and OK'd by instructor Do oil rings ‘turn and provide sufficiont lubrication after machine (48 ronning? Ars thers any dof2cts, and any unusual noises: in the maahine after it is minning? ed “Note here the maxim end minisem currant ratings of sll the field rheostats you ugsd in the tast. No. | Mare Rasistance Curr Rating con ees ciaeaenresitepianan sare ncmame stein: oS i Note defects hers: (Correct thom, if pessidie) (b) oO 127) #4-AC OPEN-CIRCUIT SATURATION CURVE, SHORT-CIRCUIT SATURATION CURVE AND SYNCEROMOUS IMPEDANCE CURVE Procedures: Data taken in this test is used in #5-AC and shovld be preserved. 1. Use a low-range DC ameter, and a high-range AC ammeter and voltmeter, also a hign-resistance field rhsostat. 2. With all switches in the alternator field and stator circuits ‘open, bring the machine up te spesd. 3. Record ths voltage due to residual magnetism, then with all the field resistance turned in, close ths fisld switch and take sirultanzous readings of field current, frequency and voltag3 for a series of ascending values of fisid currant up to the maximum. Feep the frequency constant and take about aicht readings. Always hring ths field current up to the desired valus to prevent inaccurate results due to hysteresis. 4 Reduces the fiold current in abort sight steps, taking readings as in (3) and always bring th: field currmmt down to the desired value. The last voltage reading should b¢ taat du2 to rosidual magnotism. 5. With all the fictld resistance turned in, shor* circuit the stator of ths alternator through She dynamomater hoard, take roadings of ths field currant, and 3:ach lins current, then optn tho thre singl.s pole switches on ths dynamomster board and read the voltage across cach phase corresnonding to th2 valucs of short-circuit current obtained. One set of readings should be takon with the field switch opon. 6. Repeat (5) for a series of short-cirerit currents up to 125% full-load current valus of the alternator. Take six readings including on? set with fisld switch open. Data: Tabulate all observations on a standard data sheer Curves: Plot on one standard sheet ee opan-cirenit and saort~circult saturation curves using as ordinates, for the former, terminal volts for the latter, short-circuit current, and as anecinsas, 5 Se ‘ftald currents. Yollow instructions given in th? general éire Stionse Plot on a secend standard sheet th: synchronous imoesdance currs, using short-circuit currents as auscissas, and as ordinates, the sorminal volts obtained when the stator circuit is opened. (c) Cy rer) Answers to qu2stions 1-5 inclusive should be approved before start~ ing the test, the remainder to be answsred in the final report. l. hat is meant by the open-circuit saturation curve? 2- Hew may a ao v7 light sne2d wariation be corrected for if it occurs in making the tes fe) 8 for this curve and wiry? 3. What is meant dy the short-circuit saturation curve? 4. Why is the current in the short-circuit test practically indep- endent of the speed? 5. What is msant by synchronous impedance and how is it obtained? 5. Explain the form of the opan-circult saturation curve you obtained. 7. Explain the form of the short-circuit saturation curve you obtained. 8. Why will the current in a short-circuit saturation curve rum much lower than on a direct current curve of the same sort? 9. What dsterminss the power factor in this case? 10. Caiculats the synchronous imedence for the rat7d value of cure rent. oo li. Armaturs reaction is somatimss spoken ef as a counter magneto- motive force. Why? ‘12. The E.M.F. of stlf-induction is often referred to as a cowiter FL F. Why? References: 5. & T. po. 125-126, 130-131. Magnusson po. 216-296. Gray Art. 272, 275. F. & E. Art. 62-64. Smith pp. l€1-171, 125-193. Dawes po. 142-155. Karap 3toff po. 537-541, Vol.I; pp. 129-150, Vol. II. R. &T. Po. 227-245. ; (a) DATA SHEET #4-AC i Open Circuit Saturation. Fld. Arm. Volts Freq. Romarks Am. |_# : Const. # 1~2:1-3 | 2-3 Av. | # __ Ascending L 4 Desewnding _{ Short Circuit Saturation & Synchronous Impsdancs | Fld. ; Short Circuit Amp. ‘Syn. Inmpod. Volts | Freq. Amp.| 4 ae ; Const. 1 ' Approved (a) Expt. ¢ Title: Date “hae. comisctions as a tua j on @ granh sheet the ly used in. exneriment. Disgram of Comnestions; Sketch neatly with pencil i Apparatus: Note name plate data of all macnines used: Station # Name , Make Marder Type Form hoses: enter ~ Ci — Yolts | Ammeres EW. of) OBE. Frequency | Spead Phase Instrumants: Note makc, number, etc., cf all meters, instruments, and misceilancous squinmant used. , Meter | Make Numbor | Medel Type Ranga Capacity _ Remarks en eee ad “— i i t ene ae mat ; ee 9 ge ee gD ent “ i Articie Numo2r issceription | i ! beseee . (a) Erot. Title Date Insnection: This should he made for every experiment performed, defects noted and corrected whensver possibls. 1. Is there sufficient oil in the bearings? Te eee aan nanan nana neneeeneeanaee 2. Arce the brushes badly worn? Incorrectly 92%? 3. Is commtator rough ar pitted? 4. Doss armatur? turn sasily? 5. Ara all connections corrsct? 6. Ar2 couplings or pelted conn3ctions pronerly mad2?__ 7. Is machine claar of tools and forsign particiss? 8. Have your wiring inspects7d and OM'd by instructor 9. Do oil rings turn end provide sufficient lubrication after machine <3 running? 10. Ar? thers any deftcts, and any umusual nois3s in the machine after it is ruming? ll. Note here the maximum and minimum currmt ratings of all the field rheostats you used in the test. No. | Make Resistance Current Rating Ohms Max. Min. Note defects here: (Correct them, if possible) (bo) 68 #5~AC ZERO POWER-FACTOR SATURATION CURVE Procedure: This test should be made on the alternator used in 44-AC. In case this machine is not available that part of #4-AC required for this test should be repeated. See curve instructions below. 1. The prime mover M, used in synchronizing the a.c. motor. (see Expt. #3-AC) should be a De motor which can be start7d with a water rhsostat in its armatura circuit. After synchronizing, the load due to the stray power and other lossas of the synchronous motor should be transferred from the altarnator to the DC motor M, as follows: | $ Adjust the alternator for unity power-factor (sce Expt. #3-AC), check the comscted wattmeters for proper indication (see Expt. #8~-AC) and by propsr adjustment of ths water rheostat in the armature circuit of M,, ths wattmater readings can be reduced to zero indicating that the alternator is opsrating at no-load. Note ths currant and voltage supplisd to M, and kesp their product constant throughout the test. 3. Starting with the alternator field as low as consistently possivls, undersxcite tha synchronous motor fisld until tho lin2 current is equal to ths rated full-load current valu? of the alternator, the powser-factor at tho same time being as n3ar zero as possible. Take raadings of all meters. Keep the line current and frequency constant and the power-factor as near zero as possible throughout the test. 4. Raise the excitation of the alternator in steps and corrsspond~ ingly decraass ths excitation of ths synchronous motor ke2ping tha line current and frequency constant and the power-factor as near zero as possible, and taka readings as in (3) for a sorizs of field curront valu3s up to the maximum possibl> alternator excitation. Data: Tabulats all obtservations on a standard data shoot. Curves: 1. Plot on a standard sheet tho zero powsr-factor saturation ovrva, using alternator field currents as a.scissae and corresponding vols .¢2s as ordinates. Follow instructions given in the general directions. 2. On the same shest plot the ascending values of the open-circuit saturation curve obtain:d in #4-AC. (c) 69 Alm rt HSE uastions Answers to questions 1~3 inclusive should be aporoved before start- ing the test, the remainder to he answered in the final report. l. What is the object of taking a zero-power factor curve? 2- Descrive briefly three methods for making tests and computations of the regulation of alternators. 3. “hich is the most preferable and why is it not generally used? 4, Explain why the full load zero yowsr-factor saturation curve is more easily taken, and more rsliabls, than that for unity. powsr-factor. 5. Shov how at zero-powsr-factor the thrse sources of voltage drop nd tha t3arminal volts ar> related vsctoriailly. 580] 6. Show how the optimistic zero povor-factor saturation curve may be deduced, fron tha no-load curva and the short-circuit characteristic. 7. Show how the pessimistic curve may be obtainsd from the same curves. 8. Show how to derive ths z2ro pnow2r-factor saturation curva from the no-load curves by the Potisr method, when the zero and one other point on it ars known. 9. What comoonent of voltage drop is noglectsd in the pessimistic method? In the optimistic msthod? 10. With what sort of a saturation curves would the pessimistic and cotimistic methods give the sams results? ll. Is it possible to obtain a power-factor of zaro? 12. Why is @ power-factor of 204 as good as a power-fuctor of 209 for all practical purposss? References: Std. Hdbke. Sect. O4, Art. 585-586, 4th ed.; 2399, 45904, Ssh ed. A.I.=.2. Art. 585-586. Thoma] sn pp. 96-101, Karapstoff pp. 563-569, Vol. I, po. 120-150, Vol. II. Hay Art. 80, 81, 84-87. 5S. & F. Vol.II, pp.125-131, Nos. 53-55, 59. Thompson Vol.II, pp. 253, 292. Lawrence Chanter VY. Dawes pp. 128-159. R. &T. pp. 227-242. (4) 70 #5-AC DATA SHEET Station: = Alternator | Motor Fid. Armature Volis Armature Amp. Freq. |Power, Fld. Amp. sal _ # Const.} Factor! Amp. iF 1-2) 1-3 i) 223 7 Av, I oi2 3 Av. i# # 4 ' : ! t + i | ; + i ‘ r t i Approved: (e) Erpt.# Title: Date re Diesvan of Commections;: Sketch neatly with nencil on a graph sheet the Cenaections at actually used in experiment. Arvcaratus; Note name plate data of all machines used: | were | Make Number Type Form - Volts | Ammares K.Ws, | HLT. | Frequency | Sraod Phase : L Instruments; Nova mako, number, etc., of all meters, instrumonts, and miscallanccus seulipmant used. Veter; Make | Nuchsr [Model [ Tyne | Ranga Capacity | Romarks ; t t Articts Numb 3> Description Articia | “umber | Deserintion j (a) Title Date inspection: This should he made for every experiment performed, defects neh erent nt aie 9. 10. ll. noted and corrected whensver possibl3. Is there sufficient oil in the earings? Are the brushes badly worn? Incorrectly set? Is commtator rough or pitted? Doss armatur? turn sasily? eens . Are all comnections corract? Aro couplings or belted connactions properly made? Is machine clear of tools and foreign particles? Hava your wiring inspsctod and OK'd by instructor Do oil rings turn and provide sufficient lubrication after machins ts running? Ars thore any def2cts, and any unusual noises in the machine after it is running? Note hare the maximem and minimum current ratings of all the field rheostats you used in the test. No. | Make Rosistance Current Rating Oams Max. Min. Note defects hers: (Correct them, if possibile) (b) 71 #6-A0 SHORT-CIRCUIT AND OPEN-CIRCUIT CORE LOSS OF AN ALTERNATOR Procedure: 1. Use two low-rang? DC ammeters, a high-range DC ammeter and veltmster, a high-range AC ammster and voltmeter, and a high resistance ficléd rhoostat. 2. Couple ths emall (special) D.C. motor and the alternator together and bring tho eltornator up to normal syesd. Short-cirecult the stator cf tha alternator oy connecting together thas line (not alvsenator) sides or the 8-P.S.7. svitehes en the dynamometer hosrd and closing these switehes. With the altornator fisld switch oren read all instruments. With @ high resistance in the alternator field | circuit, clos3 its field switch and read instrvments. Be 22ping the alternator spetd and the motor excitations constant, raise th? excitation of the alternator and take r noadings as in (8) for about five valuss of short-circuit current uw to the maximum normal rated. full-load currant of the machine. 4. (Qnooen th? short-circuit on the altarnator and tak3 a set of recdings on Gll instruments for a sorizs of about ten voluts of fisld current from zero to th? maximum. Xasp th? alternator spe2d and tho motor excitation constant at ths values us2d in tno short-circuit test. 5. Keeping the alternator speed and she motor excitation constant at the values used in (3) and (4), obtain the friction loss of the alter~ nator by driving it with fisid and ling switches open. 6. Run ths motor disconnected from the alternator, with the same excitation and so3eds as it had in (3), (4) and (5), and take readings as b3fore. , % Measur> the resistance of the motor armatur, 8. Determin: the aquivalent resistance of tha alternator stater as follows: Measures tha RI drop betweon each pair of tarmincis, usinc the sam? @quipmont and motaod as in (7), add thse three valuss thus obtain ed and divide the sum bv 2. Ths quotiant is the resistence desired. pte 5 i> 9. Calculate the motor stray-powar loss, the alternator frict loss, and the short-circuit and open-circuit core losses. ‘Data: Tabulate all observations on a standard data sheet. Curves: Plot on the same standard curve shee+, the short-ciroult co and load losses as ordinates against sacrt-oircuit currents 43 Plot also the open-circuit core losses as ordinates against corres (c) 73 “A6-AC Curves contd. alternator fisld currents as abscissae. Follow instructions given in the general directions. Questions: Anewors to questions 1-8 inclusive should be approved defore starting the test, the remainder to 02 answered in ths final report. 1. What is maant by the core loss of an alternator? 2 Wnat are the hysteresis losses? Eddy current losses? 3. What is the object of the short-circuit core loss test? . 4. What is meant by the loal loss? How is it dstercinsd? Is the value thus obtained correct? What assumption is made? Why? 5. What causes the load lossas? 6 What losses remain constant during the test? What losses vary? 7. What conditions govarn the motor speed and excitation? Why? 8. Why should a small alternator excitation be used when the stator is short-circuited? 9. Expross in the form of equations th2 following: Motor stray pow3r, alternator friction loss, the short-circuit cors-loss and the open-circuit cors-loss. Explain sach squation. 10. Explain tho method of obtaining the equival nt resistance in instruction (8), stating why it appliss equally well to both Y- and delta-connsct3d stators. ll. Knowing that the stator is either Y- or delta-connected, ard impossivls to saparate into its phases, explain hoy the resistances por pnas® can 03 determined, from the RI drop m:asured across any pair ¢* stator terminals. References: smith pp. 194-200, 228-235, 284, 285. Magnussen pp. 115-122, 231-232. Gray Art. 105-110, 227. Karap2toff pp. 541-542 Vol.I pp. 120-150 Vol.TIi. R. &T. Pp. 245-249. Lawrence p. 123. (a) 73 Observations D.C. Uotor Read. Fid. Arm. ; Arm. i No. Amo Volts {| Amp Speed | Remarks Const. | # ie Const. ; 1 a {| Mctor Stray Power Loss 2 Alsernanor Friction Loss 3 Suots-cireuit Core Loss 4 it vo 4 tt 5 ‘" 1 it 1 6 Ei a bi t 7 v t ob bi 8 ' tt it " 9 Open-circuit Core Loss 10 " " ‘t v li t it tt i" is t " i 13 T t f ft 14 " i" i" i" 15 it 1 ) " 16 bi tt " " 17 " wt it tt 18 i ft tt tt ft Motor Armature Resistance Lap Winding A B , CEB/A D R40 (6 Amp. Volts; Kes. Ne. True Res. - dh Fd Ohms Poles Ohms i Approved: (e) 74 yS-AC DATA SHEET #2 Observations Alternator Rdg, Fid. Line Amp. i Terminal Volts Sreed No. Arp. a ft Const. $ 1 |2[3 / aAv.¢} 1-2 11-3 [2-3 Tav.D a 5 2 b 4a 5 3) 7 8 2 10 VW L4 O15 15 7 18 Stator Pesistance Volts Line Amo Resistance per Equivalent : rid rhase ohms Resistance 1-2 | 1-3 | 2+3 1 2 3 1~2 {1-3 | 2-3 |Sum M=Sum/2 AV. (£) Approved: #S-AC DATA SHEET £3 i D.C. Motor Calculations Reading: Arm | Arm. | Arm. | Brush Total Stray — No. Input | Res. ;Copper!Contact | Copper Power Loss Watts | Ohms | Loss | Loss Logs (Const. ) Watts | Watts Watts Watts | 2sA3 FF !G=FAe | Hop T=G+H K=k-1 lif Reo 2 3 i oo 4 3 UT t om on 4 fn " tt 5 of Wt 6 { t t on a 1 " ot 8 it of 9 it of 10 tt n of 11 it fon ie) i tt 1 ff 13 | tt of 14 nt " 15 it "ont 16 " non 1? tt t 18 t off * . Calculate Fe for readirg be) and Approved: se flys valve tor all ofer read itig 3 (g) Dee eenaaeenamnememmnenmeeammnaned 75 {6-20 DATA SHEET 74 Station: Alterzator Calculations Read. Friction; Equiv. , Stator Short Load Open Loss Stator , Copper Cire. Loss Circuit No. Watts.| Res. oss Core Loss | Watts Core Loss onst.| Ohms Watts Watts Assumed (Watts. Ta-x-T Ti WalC? YP OFE-E-T-T-i] Ps0/3_S=E-E-E-T 3 tot F 3 " it n + as "on ff 5 " nu tt 6 bf " t i 7 " t ff a 8 ftom of 9 ft ow ake) " " " Li " of ff { 1 2 " "! " 13 ' ft Li 4 1 roo 15 tt " W 15 v " nt 1? " bi] " 18 '" " tt * Calcviate L for reading #2 and vsé is valve ror all other readrgs Approved: (a) Exp+. $ Title: Yate Diegram of Commections: Sketch neatly with nencil on a graph sheet the connections as actunily used in experiment. Apraratus; Note name plate data of all machines used: ema cee natn Station ¢ Nama; “Make ____ Nemoer Type Form J — Se oat eon Volts | Amporgs KAW Ut. | Frequency | Sreed | Phase Instruments: Note maks, number, etc., of all metars, instrumantse, and misceliancous eculrmant used. Meter{ Make { Nurber | Medal | Typs | “Range Capacity [ Romarks } Articia Number 7 Deseriptioen 7 Articis Number Deserintion {a) Expt. Title . ____ Date . Inspection: This should be made for every experiment performed, defects 1. ae ao fF A 10. noted and corrected whenever possibl3. Is there sufficient oil in the bearings? Are the brushes badly worn? Incorrectly set? Ts commtator rough ar pitted? Doss armatur? turn sasily? Are all connsetions corract? Are couplings or pelted conmnsactions proporly mad¢7 Is machines clear of toole and forsign particles? Have your wiring inspsct3d and OK'd by instructor Do oil rings turn and provide sufficient lubrication after machins $s running? Ars there any dsf3cts, and any unusual noises in the machine after it is running? Note here the maximum and minimum currant ratings of all the field Theostats you used in the test. No. | Make R3sistance Current Rating Ohms Maxx. Min. Note defects hore: (Correct them, if possible) (b) 77 #7-AC PARALLEL OPERATION OF ALTERNATORS . Procedure: 1. Use two low~range DC ammeters, a high-range AC ammeter, a high- range AC voltmeter and a frequency indicator. 2. Bring one of the alternators A; up to its rated spesd and voltage and apply a load to it. Bring tho otrer alternator up +0 its rated speed and voltage and synchronize it with A) (sso Expt. #3-AC). In order to divids the load equally betwsan the machinss it is necessary to in- crease the torqus of A, by lowering the excitation of its d.c. driving motor. To kez the frdéquoncy and bus-bar voltag: constant at the sams time the torque of A, should be raducad correspondingly by raising the excitation of its prims mover. Equal loads will bo indicated by equal _ ammeter readings. ; Cross-currents b3tween the two machines can bé practically reduced to zoro by adjusting the alternator field excitations until the sua of the machine ammeter readings is a minimum, raising the excitation of one alternator while lowering that of the other, thus kesping the bus-bar voltags constant. 3. Keeping the bus-bar voltags and load current constant throughout take readings of all meters wuider*the following conditions: (a) A, operating alone at rated voltage and full-load. (») A as before and A, at no-load in parallel with the line. (c) A, and Ag supplying equal power to the load and the sum of the machine ammeter réadings equal to the load current or nearly so (cross-current practically zero). (a) A, and A, sharing the load unequally. Adjust the alter- nator excitation so that the sum of th> machine ammeter readings is a minimum (cross-current a minimum). (e) A, and sharing the load equally but with wmequal excitations (fairly largs cross-curr2nt). 4. Try synchronizing with a 300-volt voltmeter across the line switch in place of the lamp. ot Data: Tabulate all obsarvations on a standard data shest. Questions: Answsrs to questions 1-7 inclusive should »¢ approved bofore start ing the t3st, the remainder to bs answered in the final report. 1. State four conditions that must be fulfilled >efors two alter- nators can be connscted in parallel. 2 Draw a diagram showing how ons synchronizing larm is used to synchronize two single phas> alternators. (c) 78 £7-8C Qusstions contd. 3. When should the switch b2 closed in this case? What rust be the ' woltage rating of ths lamp? 4. If two lamps are used, show two ways in which they can be con= nected and t311 when ths lins switch should ba closed in oach case. 5. Discuss the relativa merits of using lamps with crossed and direct connections. 6 Show the way in which synchronizing lamps may vo connected three- phaso to synchronize dark; to synchronize light. 7. (If the phass rotation of the incoming machine is wrong, how may it be changed? 8. How may synchronizing lamps on a three-phase machine or system b2 connected to show whether the incoming machine is too slow or fast? Explain ths action in this case. 9. In & permanent thres-phase installation how many synchronizing lamps would ordinarily be used, and why? 10. Explain briefly the operation of synchroscopss or synchronism indicators and their advantages ovsr lamps. ll. Explain the action of the circulating current upon both alter- lz. If the field excitation of one alternator is reduced, what is the effect of the circulating current on that machine? Upon the other machine? 13. If the torque of the prime-mover of one set is reduced, what is the effect of the reduction upon the alternator of that sét? 14. If both alternators are driven by DC shunt motors, explain the effect of raising the excitation of My, Mo, of Ay, Ap. 15. Compare the method of shifting loads on parallel-operated DC generators.with that used on alternators. References: $.&7. pp. 142-147. Magnusson Pp. 233-256. Gray Art. 279-288. F. & E. Art. 68-77. Smith pp. 200-206. Dawes pp. 125, 163. Karapstoff pp» 570-581 Vol.J; pp. 120-150 Vol.II. R. & T. pp. 250. (4) Station: 79 DATA SHEET Alternetor #1 Alternator #2 ' Tine if Stator Amp.I' o Zid. Amp. Stator ; id. | Volts | Amp.I, (| Freq. Amp." Amp. Const. Cons¢.| Const} Remarks ti it rf HE e Al alone Full Ld. AL FIC La #2 No Ld. #1 Hif. Ld. $2 | Fl — we Ynequal Ld. T'4I" min. HS Load #o 4 Load Unequal Excitat. Anproved: (8) Expt. ¢ Title: Date Diagram of Connections: Sketch neatly with pencil on a graph sheet the comactions as actually used in experiment. Anparatus: Note name plate data of all machines used: Station # Name Make Nunber Type Form - — Volts | Ammeres K.W. H.P. Frequency Spead Phase Instruments: Note make, number, ¢tc., of all meters, instrumsnts, and miscellancous squinmant used. Meter; Make Number | Model Typs Range Capacity Romarks frticie | Number asceription Article | Somber 7 Deserintion | (a) Title Date HH er Imspection: This should be made for every experiment performed, defects noted and corrected whenever possibvls. i. Is there sufficient ofl in ths bearings? 2 Are the bruchee badly worn? Incorrectly set? 3. Is commtator rouga or pitted? 4. Doss armatur? turn sasily?__ 5. Are all connections corrsct? . 6. Aro couplings or b2] tad connactions proparly made? : 7. Is machines cloar of tools and forsign particiss? 8. Hev2 your wiring inspectad ané. OK'd by instructor 9. Do ofl rings turn and mrovide sufficient inbrication after machina 3 racing? 10. Ars ther? anv def3ets, and any unusual nojisse in the machine after it is ramming? _ ll. Note hare the maximm and minismm currant ratings of all the field rheostats you used in the test. No. ; Maks Rosistance Current Rating * Note defects nera: (Correct them, if possibie) (o) 80 78-AC SYNCHRONOUS MOTOR "V" CURVES Pro edure: 1. Use a low-range DC ammeter, a high-range DC ammeter and voltmeter, a nigh-range AC ammeter and voltmeter, a frequency indicator, a power- factor indicator, two wattmeters, and special tast table. 2. Bring the motor up to spesd and synchronize with the 100-volt AC mains. Check the power facter indicator as in Expt. #3-AC. In. order that wattmeters indicate corrsctly it is necessary to connect them in a definite phase r:lation. It is also necessary to kmow when using two watt-metors in a thret-phase circuit whether their readings should be added or subtracted. For oxample, at writ’ power-factor the two wattmetors should each indicat? the same if the load is balanced; at 50% power-factor ono of ths watt-meters should read zero, while below 50% it should indicat: negatively and its reading (obtained after rovers~ ing 3ither the series or potential coil comsections) should be subtract- ed from that of the other mater to obtain the correct total power. If conn3etion diagrams ars availahbl2 thoy should bs followsd care- fully. A chock on ths prover connaction of two wattmetars on a thr oe-phase balanced circuit ‘rnos? power factor can b2 controlled may be made as follows: If the wastmeters have reversing switches (notential coil) s7t these for dirzet reading. Bring tho power factor to wiity as in Expt. Fo-AC, the lin>? current at this valuc being a minimum Both wattmeters should now read alik> (taking account of their multiplying constants). If one of them is nesativs, do not touch the roversirg switch, but reverse either the serics or the sotential coil connections taking prop2r nro- cautions to protect yourssif and tho meter. Both wattmetars will thon bs connectod so that their readings ar3 positive and should 53: added. If on2 of the wattmeters indicates negative ab any time during th2 test us® tha raversing switch and subtract the reading from the othor watt moter roading +o zet the correct result. 3. Operat>? the machine at no-load, kesp th? impressed E.M.F. and the frequency constant, and tak? ammotor and wattmeter readings for succsssiva values of fisld current ranging from minimum possibls to maximum possible values. If motor falls ont of step, pull line switches on dynamometer board im-odiataly. 4. Repeat (3) running ths mctor at full load. Data: Tebulate. cll observations on a standard data sheet. Curves: 1. Plot on one standard sheet curves showing th: relation betwean power factors, line currents and watts at no-load as ordinates, and field currents as avscissas. Follow instructions given in the general directions. 2. On a second standard shest plot curves for full-load, similar to thoss in (1). (c) i 81 78-AC Questions: Answers to questions 1-4 inclusive should be approved hefore start- ing the test, the remainder to be answered in the final report. i. Why must the motor always revolve in synchronism with the frequency of the line? 2. What is meant by a synchronous motor "V" curve? 3. Why doss a DC generator, giving current, form a particularly convenient load for this test? 4. Explain sevaral methods of starting synchronous motors. 5. Discuss the shape of the "V" curves for different loads. 6. Why ars the two sides of the curve not symetrical? References: 5S. &T. po. 139-141. ‘Magnusson pp. 245-260. Gray Art. 279-288. F. & E. Art. 68-77, Smith po. 207-216, 219-227. Dawes po. GOE-Sea. Karapetoff p- 580 Vol.I; pp. 120-150 Yol.It. R. & T. PD. 258-265. (4) 82 #8-AC DATA SHERT #1 Station: D.C. Generator Synchronous ifotor | Read.| Line Volts |Tsrminal Volts E | Line Am. IT | = Volt No. { Amp. Const. Censtant. is MPs « Const. /# a i | ro T-2/1-3 2-3] av. 11318 | Av. | P=aIVS 1 Hi 2 i i 3 4 i 5 6 : j 8 E 9 ni 10 il i i 12 | i 13 : 14 i6 : ‘ 1? j 18 ' j ig T 20 | | i Approved (2) 83 Fe-AC DATA SHRET #2 Stations : Syncaronous Motor ‘ Watts Input Power Factor | Fld. ° Freq. Read. _W dt Am. | Const.} Remarks 2 LK 2 1K | Totaly W/P | Road. L No Load 2 i I 2 | Oo | : 4 4. 5 a é i i 5 rT 10 +o 1 Full. Load 12 13 14 C 15 16 fr i? | i ig i : is =e KE = multiplying factor Aoproved: (f) Expt. Title: Date . Disgram of Connections; Sketch neatly with pencil on a grapvh sheet the comisctions as actually used in exnerinent. Apparatus; Nete name plate data of all machines used: yps Form {__Name | Make Narber Ty _ t i i = Volts | Amperes K.W. | FP. | Frequency Snead | Phase 1 i Instruments: Note maks, number, etc., cf all meters, inetrumonits, and miscellanccus squinmant us. Veter, Make Numhsr ; Modol Type { Rengs | Capacity | Remarks i Articia Numoer Lescrinticna a (a) Lzpt. Title Date Inspection: This should be made for every experiment performed, defects noted and corrected whenever possibls. l. Is thers sufficient oil in the bearings? 2. Ars the brushes badly worn? Incorrectly set? 3. Is commtator rough or pitted? 4. Do3s armatur? turn 3asily? 5. Are all connections corract? | 6. Ar2 couplings or belted conn2ctions propsrly mad? 7. Ts machine clear of tools and forsign particles? 8. Have your wiring inspactod and OF'd by instructor __ 9. Do oil rings turn and provide sufficient lubrication after machine is running? 10. Ars there any defects, and any urusual noises in the machine after it is running? ll. Note hers the max imam and minimum currant ratings of ail the fiela rheostats you used in the tast. No. Make Rasistance Current Rating i % Note defects here: (Correct them, if possible) (bo) B4 #9 39~AC SYNCHRONOUS MOTOR CURRENT AND POWER-FACTOR CURVES WITE CONSTAM? ZXCITATION Procedure: 1. Use a low-rangs DO ammoter, a high-range DC ammetor and voltmeter, @ high-rang? ACG ammeter and voltmeter, two watimeters, a power-factor indicator and a frequency indicator. 2. Synehronize tho motor, check th> power factor indicator and the wattmeter connsctions as in Expt. #3~A0 and #8-~Ac. 3. Adjust the power factor toe 0.6 lagging and keep the immressed e.m.f., the frequency and the motor field constant. Take eight sets of readings of all tas meters for motor loads ranging from zero to approx- imately 125% full load. (4. Repest (3) after adjusting the power factor to 0.6 leading. Data: Tabulate all observations on a standard data sheet. Plot on the same standard sheet curves showing the relation between currsnts, watts and powor-frictors as ordinates, and DC watts outnut as abscissas, Follow instructions given in the general directions. Questions: Answer ths following in the final report. 1. Explain with the revolving vector or circle diagram how, by chang- ing its phase relation, the synchronous motor takes increased currant, when its load is inersased. oo 2- What otaer phenomenon combines with this to take the place of ths drop in spesd of othsr typ2s of motors, 2s a means of increasing the currant as tho load increases? 3. Show vy the voctor diagram ths effect of inereasing load upor tne phas? relation of line currsnt ard voltages. 4 Discuss the bearing of this mon the loading of motors used to supcly leading current for th2 purpose of improving tho line power-factor. 5. By the circls diagram, exelain th3 sudden stopping of the motor when too muck overloaded, and tha effact of excitation upon th? load it will carry. References: 5. &T. pre 132-135, 141-142. , . Megnusson pp. 260-266. Gray Art. 279-287, 319-321. F.& &. Art. 68-88. Smith pp. 216-227. 5S. &F. Yol.II, No. 67. Dawes pp 305-352. Karap2toff p. 580 Vol.I; pp. 120-150 Vol.ITI. R. & T. pp- 258-265. (c) 85 DATA SHEW?T #1 Station: mead DC Gonsraton Synchronous Motor No./Line Wolts Watts [fld. {@orminal Volts El Lino Amps ! Volt. pro. Outouthde. if Const. it I} Am. # Const.!1--2 |1~5 '2-8iav. | 2 | 2 | Sy Av.j Pent V3] 1 H i 3 3 5 H 6 ? 8 9 i il) i il } 12 13 14 15 i 15 L Approved: (a) pe peaorddy JoZ,OTT BUTATAPIINE = ¥ i St i ST ¥T ST St TT oT “PEPPONC TAINS “PTE Sail 6 gt ee | 9 i, Go! # PEoYy d/ik TeI0L | xX (a x T! "481109 if aoe SyICUEY "bea # ih “peer ; Io40et Temog anduy s44qey | IO4Ol] snoicayousls 4 UCT QUIS oF GagHs Viva oi Expt. # Title: Yate -Diagrem of Connections: Sketch neatly with pencil on a graph sheet the connections as actually used in experiment. Anvaratus: Note name plate data of all machines used: Ah de Station ¢ * , * ‘a * é | name | Make Number Type Form _ |... Volts [amperes | K.W. i HID. Frequency | Snead Phase { i Inetrumsnts: Note makes, number, etc., cf all motere, instruments, and tiscellancous squinrmant usad. Meter | Make Nuther | Medal fyps 1 Rang Capacity Romarks Article ivumb2r Description Lxpt. Title “Date Insnection: This shceuld be made for every experiment performed, defects noted and corrected whenever possibls. 1. Is there sufficiant oil in th bearings? 2. Are the trushes badly worn? Incorrectly set? ue Is commutator rough er pitted? 4. Doss armatur? turn sasily? 5. | Are all connections corract? 6. r2 couplings or b2lted connections properly mad2?____ 7. Is machine clear of tools and forsign particlss? 8. Have your wiring inspactod and OF'd by inatructor 9. Do oil rings turn and provide sufficient lubrication after machine és ruuing? 10. Are there any deftcts, and any unusual noig3s in the machine after it is running? —— ll. Note here the maximm and minimum current ratings of all tha field rheostats you ussd4 in the test. No. Make Rasistance Current Rating Cbs Vax. iin. Note defects here: (Correct them, if possible) (b) 8” atO-AC EFFICIENCY AND EXTTRUAL CRAPACTERISTIC OF A ROTARY CONTE RTER Procedure: 1. Use a low-range DC amzeter, a nigh-range DC ammeter and voltmeter, @ high-ranze AC aureter and voltmeter, a power-factor indicator,. frequency meter and wattmeters. : 2. Start and synchronize the rotary converter to a thr3e-nhase source as follows: R3fsr to.the given wiring diasran. Oyen all switches and the water rheostat circuit. Close switches A ani B and tring the converter up to sped, using th? water rheostat. Clos: switch © after converter is rumnine. Synchronize the converter with the AC source provided. Clicse switch D ani onan RB. Oosen switch ¢ and ths water rheostat circuit Oven switch A ani clos? switch BF. The converter is now ready to load by msans of the water rheostat. Cneck tha powsr-factor indicator and wattmeter connections as in Exnt. #3-AC and 48-AC 3 Adjust the field current til the current input is a minimum at no-lond, and keeping this visi current, the frequinecy and immressed voltagc? constant, taxe raadings of wt meters for a seri2s of gicht values of DC amperes from z3ro to normal rat24 eulieioad currant. 4. Repent (3) runminz tas converter single-nhas3._ 5. Repeat (3) rumning ths converter from a six-phase source. Tesulat @ all observations on a standard data snes. Curves: 1. Plot on ths same standard sh2at th: effici- smey curvas for six- pnas2, thr2s-nhase and singl g-phase op3ration, using 3fficianciss in % as ordinates and watts outnut as ahsciseas. Follow instructions given in the general dir3ections. eo. Plot cn anothe: standard shest th? oxternal characteristic for Six-“hase, thrsae-phass and singlo-ohas: oo2ration, using DC voltrees as ordinat3s, and DO currents as zhscise:is. #LO-AC Questions: 88 Answers to the following questions should be apnroved before start- ing the test: 1. Discuss the 2 source in waking this test. States the a 2. Disc uss tne nessibility of loading a merits of some of its disaivantages. 3. Name ail state which one finds in such a case. References: S$. & T. Magnusson Gray RF. a F. Smith Dawss R. &T. Karapeatoff 4“ vA 185-189. DD. 258-290. Art. 345-354. Art. 75, 84=+96. po. 243-270, po. 342-376: p- 269. tg rae es pp. 120-163 Vol.II. (a) various methods of starting a rotary converter. cok on ths a.c. starting such a method and alsa possidls uses for a synchronous converter, and most frequent anplicati ion, also whers it is used 89 tpesourdey Toyoe_ SUPATATI MP = ¥ Oe 6 ST at 9T St tT et ot Tt Ot 7 t 1 ak COC SHLD COLE | COM peer aT La . FOL a Sel tT SAiied (aye ett [=a S-ers-tle-t tt 7 va # *qsu0n IOZOVT *besiz TOMO A andut * chy I "4.8109 pee x! 44M 4TOA ‘sduyy eutT H S4TOA mrey, QE ! i ' L OSA OLS Ty GaasS Viva OV-OlF (e) #10-AC Station: DATA SHEET #2 90 D.C. End Bing Hs ; Waste : atput Remarks Three-phass Single-phase =] Olcaloo|totorlie foalag! mie tol 13 14 Six-paase 15 sa 16 Yr t 18 ig 20 (f) Approved: Erps.¢ Title: Date . Diagram of Connections: Sketch neatly with nencil on a graph sheet the connections as actually used in experiment. Apparatus; Note name plate data of all machines used: ay | _ ems Make Number Type Form a ae | volts TAmperes | K.W. | >. | Frequency | Sread [ Phase dinstruments: Note make, number, etc., of all matars, instruments, and miscellanccus squirmant used. Meter; Make | Number | Modal Type | Ranga Capacity { Remarks 4 Artic umber 1 Dsseription Articia ' haser 7 Doserintion (a) Lxpt. Title Date Insnection: This should be made for every experiment performed, defects noted and corrected whenever possibls. l. Is there sufficisnt oil in the bearings? 2. Are the trushss badly worn? Incorrectly 89st? 3. Is commtator rough or pitted? 4. Dose armatur? turn 3asily? 5. . Ars all connections correct? 6. Ar2 couplings or belted conmsctions pronsrly made7_. ve Is machine clear of toole and forsign particles? 8. Hav2 your wiring inspsctad and OZ'd by instructor 9. Do oil rings turn and provide sufficient lubrication after machine $s roning? 10. Ars there any deftcts, and any unusual nois2s in the machine after it is running? ll. Note here the maxima and minimum current ratings of all the field rheostats you ustd in the test. No. | Make Rasistancs Current Rating Ohms Max. i Min. Note defects here: (Correct them, if possibile) (b) 91 FLL-AC RELATION BUTVTEN D.C. VOLTS AND FIELD CURRENT OF A ROTARY CONVERTER Procedure: 1. Use the same range instruments and start and synchronize the converter as in Exnt. #10-AC. 2. Load the converter un to normal rated full-load direct current output, and kesping the impressed AC terminal volts, the froiquancy and the direct current line ampsras constant, vary the field strangth of the converter for different valuts and tak? corresponding readings of all the moters. : 3. Run the converter at no-load. Insert the regulating field into the circuit and with its rheostat contact arm set at a point. midway between the limiting stops, adjust the shunt field rheostat for the value corresponding to minimum AC line current. 4. Keeping the field current constant at the value obtained in (3), as well as the £0 terminal voltazg2, and frequancy, take readings of all miters for a series of valuis of regulatines field current varying from that givirgmaximum to that giving minimum DC voltage. Do not 4 permit the commitator to spark sxcessivaly. Data: Pabulate all obssrvations on standard data sheet. Curvas: Plot on a standard sheet two curves using DC voltages as ordinates and shunt field currents and regulating field currents as abscissas. Follow instructions civen in the seneral directions. Questions: Answer the following questions in the final report: 1. Draw a diagram, showine the ratios betw2en the AC voltaze for singls, three, four and six paass converter connections, and, hence construct a table showing the voltages referrsd to the DC voltage as wmity. Give also the corresponding virtual alternating currmt ratios in the lines and in the ermnzture conductors. (c) 92 #1i-AC Qusstions contd: 2. Explain how the voltage ratios ara affected by loading and by the power-factor. 3. Discuss the effect of excitation mon ths voltag? ratios, (a) with no inductancs between the converter and the AC supply, (b) with inductance. 4. Explain why the powsr capacity of the converter incraases with the number of phas:s used. List the capacities of single, two, three, six, and twelv2-phas? convertsrs in terms of the same machine opcrated as ad.c. gonerator. References: 5S. &T. pp. 189-190. Magnusson pp. 268-290. Gray Art. €45-354. BP. a& HE. Art. 75, 64-96. Smith op. 245-270. Dawes Po. 342-376. R. &T. p. 269. Karanatoff pp. 120-163 Vol.II. 93 spesorddy 20,0eg SuTATAPA TAH = X a BT BT at oT St oT eT T tt OT; 6 8 9 G ; ¢ ¢ e } iT pee) d/m [30m Te) SyaIT (eA Tiad bay ee tT tavie-ele-ti ent a ? i? _t. # # *gsu0g 10408 ‘A gaduy 2 * cay I *48tt09 ‘On “berg cO0 d SYP “ATOA sduy uty & S4Toacates I peey, ‘PU "OV pops 3 OV-TT# (9) #11-AC DATA SHEET #2 Station: D.C. Fnd Sht. | Rog. Volts | Line Watts Readt Fid. {| Pid. Arps. Output Remarke No.j fmp.{ Amp. Const, Const. # id # 1# Full Load 1 Varying Sht.Field Pe 3 4 5 6 . id Varying Rez Field 8 Sht. Field Const. 3 ; ic il 12 13 15 4 1? i8 19 20 i Approved: (¢ Expt. ¢ Title: Date ' Diagram of Connections: Sketch neatly with pencil on a graph sheet the connactions as actually used in exneriment. Avpvaratus: Note name plate data of all machines used: Station ¢ Name Make umber Type Form i” “| Volts | Ampsres KW. | EAP. Frequency | Speed Phase ! Instruments: Note make, mumber, etc., of all moters, instrumants, and thiscellancous squirmant usad. Meter; Make Nunber | Modal Typs Range Capacity | Romarks Article Nuno ar Pescription 7 Artisic (a) Inpt. Title Date Inspection: This shculd be made for every experiment performed, defects noted and corrected whenever possitla. 1. Is there sufficient oil in the bearings? a Are the trushes badiy worn? Incorrectly sot? 3. Is commitatcr rough or pitted? Se emetemameneaanmmen ened 4. Doss armatur? turn sasily? 5. <Are all comnections corroact? 6. Aro couplings or b3ltei connections proporly mada? 7. Is machine claar of tools and forsign particles?__ 8. Hav2 your wiring inspsctad and OF'd by instructor. 9, Do oil rings turn and provide sufficiant lubrication after machine is ronning? 10. Ars ther anv def3cts, and any unusual noises in the machine after it is ramming? od - ll. Note here the maximm and minimum current ratings of ell the field rheostats you used in the +ast. No. | Maxe Currant Rating I Note defects hera: Correct them, if possibie) (b) 95 P2i2-AC TEREE WIRT GENERATOR NIH I BALE ICED LOAD 1. Cormect the rotary converter as a three-wire generator with thres-phase AC supply and tivo bslancs coils comiscted to the two-phase terminals. Refer to connection diagram. 2. Adjust the two receiving circuits of the three-wire system so that sach takes full-i cad mrrent, and aljust the field rheostat of the generator to give its normal voltags (sum of the voltages across the circuits}, at the same time adjusting the AC voltaz2 s9 that the AC line current is a minimum (unity powsr factor). 3. Reluce the current taken in circuit A step by step util it is zero, keeping the total voltag? of che § generator constant, and AC lines currant at a minimum, and take simultanzous readings of the current i eacre lins and the voltags seross wach cirenit of the systom the owt ent in circuit B, step oy step, auit J being zarc. Tebulate all cbsarvetions ani other data neatly on a standard 3 Plot on 2 standard sheet two curves from the data ebtainsd in (3), using volts scress circuits A and 3 as ordinates, and curronts om the A side as abscissas. Fellow instrvetione givan in the sensral directions. Plot similar curves from th: data obtained in (4) using the current on ths 2 sids as abscissas. Questions: Answers to questions 1-7 inclusiv2: should b2 amnroved ? ranainier z) gtr ing the t2st, sche resainder to 5s answarsd in the final report 1. Fxrolain ths theory of the Dosre wolsky thr23-wire generator. + th ec. What are the aivantocse of a thraawirs systamn as commered wi st z > . “nat is the usual practic3? &. Waat weuld ts a of a large iwtbalanced lead on the rd by Steet P 4 systen if the newusral vire shovld be disco #12-AC Questions Contd. = O.« 7. ard three-wire 8. 9. 10. ln 12. 96 Is it advisable to fuse the neutral wire? Why? State the relative amounts of conver required on the two-wire Deseris rs Descrive Dsscrive Descrins Neseribe use of rhoostats. References: Elec. Jour _ Franklin Lanzsdorf Magnusson Dawss Karan stoft R. & fT. systems. tna Fdison three-wire syste. the split-pole thres-wirs generator. the Dettmar thorea-wire generator. the motor-ganerator halancer and its us. the method of balancing a three-wire system by the Vol. 10, pn. 690-602. pp. 85-83. Ghap. XI Chap. XY~XVI Voi.I, Gnap. IX; Yol.II, Ghap. IX. po. 375-375. po. 331-335, 506-508, Vol.I; pp. 190-1 p- 160. 3, TVol.II. QD (4) #212--AC 97 Station: Thres-Vire Generator Amp. ; Amp. (Amp. ; YJolts Volts Volts Read. A ; 3B ; {middle A 5 Total Yo. main} Const. 7 ==} === Ems : << + Anproved (e) Expt. # Title: Date Diagram of Comnections: Sketch neatly with pencil on a graph sheet the comiections as actually used in experiment. Apparatus: Note name plate data of all machines used: Station ¢ Name ; Make : Noniber Type Form 4 Volts {| Ameres KW. qe. Frequency | Speed | Phase Instruments: Noto make, mumbar, ote., of 811 meters, instrvmants, and miscailanccus equipment used. Westar, Make | itaber [Model [| fyoe | Range | Capacity Romeris Articis | Yaabsr Tbesoriotion® AFEGsio Tee somes: F io Semin (a) : Lot. Title Date dnsnestion: ‘This should he made for every experiment performed, defects neted and COrre stei whenever possibls. i. Is there sufficient oil in ‘the dearings? 2. Are the trushes padly worn? Incorrectly sst? ‘Z Is commitator rough er pitted? 4. Doss armatur? turn 3asily? 5. Are all connections corract? 6. Aro couplings or balted connactions properly mada? 7. Is machine clear of tools and foraign particles? 8. Have your wiring inspsct3d and OF 'd by instructor | 9. Do ofl rings turn and vrovide sufficient lubrication after machine és romniing? 10. Ars there any deftcts, and any urrasual noises in the machino after it is running? 11. Note here the maximim and minimum currant ratings of all the field rhsostats you used in the test. No. {| Make Rasistance Currant Rating Cnns Max. Min. Note defects hare: (Correct them, if possibia) Cb) 98 #13-AC TRAISTORER RATIO AND POLARITY Procedure: DO Polarity Metnod: 1. For the DC method, use the storace battery and a high-range DC voltmeter. 2. Refer to the given diagram of connections. Close the switch $ and cornect the voltmeter to the terminalis A and B on the high or primary side of th2 transformer, so as to deflect in the proper direction. 3. Note which transformer terminal is connected to the positive lead. of the voltmeter. Designate this terminal as positive. s 4. Transfer the voltmater leads to the terminals on the low or secondary side of ths transformer, connecting th? A lead to © and the B lead to D. 5. Oper switch S and note the direction of kick of the voltmeter neodle at ths instant the primary circuit is broken. A positive kick of th: needle indicates that th> sscondary terminal connected to the positive lead of the voltmeter is negative, and the other terminal is positivs, in oth2r words, adjacent turmin rails A and © will have unlike relative polariti2s, as will also adjacent terminals B and D. A negative kick rev2rses th? above designations. Note the polarities of the trans formers. AC Polarity -ftnod: 1. For the AC mothod, use a sp2cial hnigh-range (300V.) AC voltmeter. @- Comnect one primary terminal B to one secondary terminal D. Excits the primary winding from a 110 volt AC sourc2, and measure the voltag2? across each winding, and also across th? terminals A and C. If ta? latter voltage is grzater than that across the orimary winding, then the adjacent terminals A and C, and likewis3 B and D, have uniike relative polariti2s, othsrwiss, the adjacant terminals have liks polarities. Designate ths les star you assign to gach terminal. Ratio Test: 1. Use two high~rang 2 AC voltmeters. 2. Impress across the primary winding 25%, 50%, 75%, 100% and 125% normal rated voltage, at normal rated frequency, and note the values of primary impressed volts and secondary induced volts. Tale + least two sets cf readings. (ce) 99 p13-A a Procedure Contd. 3- Repeat (2) hyving interchanged voltmeters. Checkin, Taps: * 1. Use 2 high-range and 2 low-reng? AC voltmeter. 2. <Apoly 110 volts {C at normel rated fraeuancy to the primary winding, and tae realings of the voltage across the winding, ind also etwoen successive taps. Ths sun of the tap voltag2s should checl within pareant of ths total voltazs applied. 3. Rep2rt (2) on the secondiry windings, applying the 110 vol+ soure? to tais winding. Th sum of th2 tap vol tag2s should chasck within on? pare2nt of the total voltaze apolicd. Data: Tabulite all observations on - standard data sh33st. Draw diagrams ropresonting tht transformer windings and tactent ting the polariti> you obt.ined them, together with tha various terminil and tap nunbors. sstions: Answers to questions 1-2 inc lusive should be anvroved before start- ing the test, the remaindsr to he answered in the final report. 1. Show wnat ratios can be obtained with a transformer, having two primary and two secondary colls, there being in all ten times as many primary as stcordary turns. 2. If 2:ach primary coil is dssizned for 1000 volts and 10 amperes, at primarv voltazss can the transformer be used, what secondary 3 voltages can t@ obtained, and what will »3 the primary and secondary currents and powers transform rmzad in sach cass? Neclect lossss. Make a tabular statscent. 3. if the longth of tury and tho cur wit density are the sare in voth coils, what will 3s the relation of th? resistanc3 ine tm-to-one *r nsformsr? 4 What will t2 ths ralation of watts lost in ths two coils? 5. What will ce th2 ratio of the volts lost by the resistance in tha two coils? (4) 100 #13-AC msstions, Conttd. 6. Tsll how to test tha polarity of twe transformors which are to +e connscted in paralisl by the use of a t2st lamp or light fuse wire. References: Magnusson pp. 131-154, 150-158. Gray Art. 302-308. F. &E. Art. 97-113. Smith po. 101-156. Collins pp. 175-179. Dawes pp-:172-224. Karapstoff pp. 466-531, Vol.I; pp. 1-118, VYol.II. (e) 101 “DATA SERED Station Polarity Test i Check on Taps Term. ! D.C. -) AC Method 1 Tap | Inmmrest, % of No. ! Pol'tty! Term | Pol'ty | Volts £ Tapq Volts; Volts | Winding 4 ‘Design £8 10D] AG dt # i_4 1-2 i 4 e-9 5 5-4 8 ‘ 5-6 9 6-7 il 7-8 12 | Sum. 14 9-10 10-12 2-15 i nS-14 i Sum. Ratio Test. Term. Impr2st & Induced Volts | i Nos. gt a Remarks 25% | 506 | 750 !100% | 195% 1-8 Meter 3 i-8 1-8 hMeter 4 1-8 Ave. g~14 Meter # 9-14 9-14 ; Meter # Q~14 | Ave. natio Approved: (f) Expt.# ss Title: Date Diagram of Comnections: Sketch neatly w Cornact lone Apuaratis: Nete name plat Station ¢ @ fu © cr G oO a) asd 2 all ¥v 2 th wencil on a gr machines used: i ann sheet the amuglly used in experiment. | Name {| Make Nother Tepe Form Z = were | | 4 Volts Ammeves | EW. | HAP, Frequency | Snead Phase ee ed ‘. i | + bo i i instrum3snts: Note mak3, number, ete., of all meters, instrumants, and miscellanccus squinmant used. Meter, Male Number | Modal Typs Ranga Capacity | Homarks ve iL oe nl Article Nvumo2r boseription | Artici2 f en eee ee ae (a) Expt. TSIQ | | pate Inspection: This should be made for every experiment performed, defects “noted and corrected whenever. possiblsa. 1. Is thers sufficient of] in ta: vearings? 2. Are tha brushes vadly worn? Incorrectly set? Z Is commitator rough or pitted? 4. Doss armatur? tun easily? 5. Are all comnections corrsact? 6. Ar2 couplings or bait 22 connections properly mada? 7. Is machine clear of tools and forsign particies? oo 8. jev2 your wiring inspecti2d and OK'd by inetructor 9. Do ofl rings Same and prov ride sufficimnt lubrication aftar machina 48 running 10. Ars there any defects, and any umisval noiszs in the machine after is is running? “ee ll. Note hers the meximem end minimum currsnt ratings cf all the ficld rhéeostats you used in the test. No. | Make Rasistancs wer nt SEED Note defects here: (Correct them, if possible 3 (b) 102 Ma-AS TRANSFORMER CORE LOSSES Procedure: ot This experiment and Expt. #15-AC should be performed on the same trans- former. 1. Connect the low-voltaze winding of the transformer in conjunction with properly orotect2d meters and lines sw sch to an alternator. Determine vroper moter ratings from the transformar name-plat> and test requirements, end ohsorv2 overy possible precaution sa as not to excesd the current ratings of ammeters and especially watimeters to provent overhsating or burning tusm out. When opening or closine the lin? switch always be sure all voltmeter and wattmoter notential circuits ars opr. 2. Keeping the impressed voltage constant at normal rated value, take readings of all meters for frequencies of 0, 40, 50, 60, and 70 cycles. In reading ammeters all voltmeter and wattmeter potential ewitches should te open, as the current taken by these affect the readings. Likwise in reading wattmeters, all voltmeter switchs should be open. , 3. Xaening the frequency constant at normal rated value, tak? roadings of all m2ters for impresssd voltages of ©, 50, 75, 100, 125 and 150 volts. Observe same precautions with notantial switches as in (2). 4. Determine th resistance of the ssparats coils of each winding v7 the voltage drop method, using a low veltags d.c. sources and suitable meteors. Date: Tabulate ail observations on a standard data sheet. Curves: Plot on a standard sheet the curves of watts, amperes and power-factors as ordinates with impressed volts as abscissas. Yollow instructions given in tho general directions. On a sscond snest plot corraspondin 1f Curves using frequencizs as abscissae. Questions: Answars to qu3stions 1-2 inclusive should be aporoved before starting ths test, tho remainder to be answer2d in the final report. 1. What will nappen if a transformsr coil is used on a voltage much higher than that for which it was designed, and why? 2. Thy is it usually preferable to make connections to the low tension rather than the high tension side for this test? 3. Using your data comare the losses ani hence the heating of a 2200- volt, 60 cycis, transformer op2rating at the following voltages and frequencies: 2000-volts, 50 cycles; 2200-volts, 60 cycles; 2200-volts, 50 cycles; 2300- volts, 50 cycles; 2506-volts, 60 cycles. 4, Discuss the practice of operating standard 60 cycle apparatus on the mains of the “micipal Light Plant. 5. Tabulate reprissntative core losses, cooner losses and efficiencies of modern distribution transformers of the following KVA ratings: 1, 5, 7.5, 10, 20, 30 and 50. References: 8S. & T.. pp. 148-149 Fr. & E. Art. 97-122. Magnusson pp. 131-163. Smith pp. 101-156. Gray Art. 289-308 Collins p. 180 Std. Hdbk. Dawes pp. 172-224. R. &T. PR 199-2235 Karapetoff pp. 466-5351 VYol.I. pp- 1-118 Yol.II. (c) . #14-AC sts SHEET 193 Station: Freq.; Voltsi Arp. Watts | Volt | Power Copper Core # EF ft ft W Am. | Factor | Loss Loss it le a RI | W/ST RU2 W-RNIe | Read jk Oorract : : t r 4 K = Multiplying Factor R" is the calculated resistance of the low-voltage series or parallel combination used. Transformer Resistance Primary (niga side Gcil #2 Secondary (low side) coil #1 Volts | Amps Res. Volts AD Res. AY. AY. Coil #2 Coil #2 Volts Amp. | Res. | Voits Amp. Res. # # Rly ; é RM ie : AV s ave Aporovsd: (d) Expt .¢ Title: Date Diseram of Connections: Sketch neatly with nencil on a grapn sheet the oo ie J Pt mS a cormiactions as awtusily used in exveriment. Apparatus: Note name plate data of all machines used: Station # | Name | Make Mather Type Form a b : = Volts | Armerss K.W. | F.P. | Frequency | Spesd Phase 7 | Instruments: Note make, nurber, ete., of all meters, instruments, and miscellancous squinmant used. Meter, Make Number | Model Type Range Capacity Romarks a a pe oa $ feet nad Article Numoer Description | Articis | Dosorin tion (a) kept. Title . Date Inspection: This should he made for every experiment performed, defects noted and correctel whenever possibls. l. Is there sufficient o11 in the dearings? 2. Are the trushes badly worn? Incorrectly sat? 3. Is ceommitator rough or pitted? __ 4. Dogs armatur? turn sasily? 5. Are all connections corract? 6. Ar2 couplings or b31t24d connections properly made 7. Is machina clear of tools and forsign particiss? 8. Hav2 your wiring inspsct3d and Of'd by instructor 9. Do ofl rings turn and provide sufficiznt lubrication after machina is running? 10. Ars thore any deftcts, and any unusval noises in the machine after it is ruming? ll. Note here ths maximum and minimum currant ratings of all the field rheostats you used in the test. No. | Make Resistance Current Rating Cams Max. Min. Note defects hare: (Correct them, if possibis) (2) 104 #15~AC TRANSFORMGR COPPER LOSSES, IMPEDANCE AND RECULATION Procedure: This experiment should be performed on the same transformer used for Fxpt, #14-AC. If this transformer is not available that part of #14-AC necessary for this test should be reneated. 1. Comrect the high-voltage winding of the transformer in cenjunc- tion with properly protected meters arid Line switch te an alternator. hort-cirevit the Low-voltage winding tarough a suitable ammeter. termins the proner meter ratinzs from ths transformer name-niate and test réequiremsnts. Ths voltages of the “altor Alor saould be riduced to least six volts before closing the line switch, othervisc, the current in the transform3r and ths meters may b? excessive and burn them out. Uoserv2 avery vcssibl: pr2caution so as not to exceed the eurront ratings c 1 ‘end esprtially wattmoters to prevent overhoeting or burning them out circuits should 62 open whon opening or closinz th> line ewitcne 2. Adjust tne speed of the ganarstor to gives the reteod frequancy of tha transformer under test and take reaiings of all moters for a sories of applied voltages from the smallest sossibl> (at least six volts) to that giving the normal rated (calculated for the narticular connection, if n2 cossary) current in tho transformer windings. Obs2rv> precautions rogarding metor rardings as given in (2) of Txnt. #14-Ac. Data: Tabulate all obs2rvations on a stancard data sheet. Curves: Plot on a standard sheet curves using watimeter readiness and cal- culated copper losses as ordinates and ammsres “ abscissas. Tesignate the load losses. Follow instructions given in the general directions. Questions: Answers to questions 1-6 inclusive should be aporoved before start- "ai ing the test, the remainder to be answered in the final reanort. 1. Define regulation as apolied to a transformer. 2. Discuss tne relations of the primary and secondary rasistances, as based on the turn ratio. 3. What is meant sy "load lossast in a transformer? 4. Explain equivalent resistance and rsactance. 5. Explain affective resistance and reactance. (ce) 105 #15-AC Qusstions cont'd. 6. Why is it usually proferable to make connections to the high- tension rethor than th? low-tonsion sids for this t2st? ?. Calculate the efficiency at normal voltage, wnity vower-factor and loads of C, 1/4, 1/2, 3/4, 1, and 11/4 times normal. Make a tanular staterent and piot curve. 3. Calculate the average value of impedance and determine the rezulation at full-load for unity and for 0.7 power-factor, using the method of the A.I.E.=. Standardization Rulas. Rererancas: S$. &T. yp. 140-152 Magnus son po. 115-163. Gray Art. 289-308. ¥. & E. Art. 97-122. Smith po. 101-156. Collins p. 189 Std. Hdbkk Stand. ,Rulss. Dawes pp. 172~224. Karapetoff pe. 464-531, Vol.I; pp. 1-118, Vol.II. R. &T. pp. 199-223. 106 -#15-AC | DATA SHEET Station: Freq. Volts! Amps Watts i . > | COP : Lead ;} Imp. Const) Ft! J! W Amp | R'I'“! ReI"’ | Loss |Loss | 2 ¢ it if a r" Tot. | Read K |Corract ap pope i K = Multivolying Factor Rt is the calculated resistance of the high-voltage serizs or parallel combination used. R" is the calculated resistance of ths low-voltage series or parallel combination used. Approved: (e) Exypt.#_-sTitle: Date Disgram of Connections: Sketch neatly with pencil on a graph sheet the connections as actually used in experiment. Avparatus: Note name plate data of all machines used: Station # | Name | Make Number Type Porm 3 i weed Volts | Armeras KW. | HP. | Frequency | Snead Phase i Instrumanis: Note mako, numbsr, éte., of all meters, instruments, and s ” ; iu ? . Misc@lianccus squinment ued. Meter, Make Number | Model Tre Range Capacity Remarks nd i { Artiale Numoar boscription | Agticle | camcho2 J ca at — ove ‘| ee mend (a) Title | | Date epreretemaneeatincaeanamenerens Inspection: This should he mede for every experiment performed, defects 10. ii. noted and corrected whenever possivls. Is there sufficient oil in the bearings? Are the trushes badly worn? Incorrectly s2t? “Is commatator rough or pitted? Do3s armatur? turn sasily? Ares all comections corrsact? Ar2 couplings or belted connactions propsrly made? Is machine clear of tools and forcign particles? Hav2 your wiring inspectad and OF'd by instructor De ofl rings turn and provide sufficient lubrication after machina ds running? Are? thsre any deftcts, and any unusual noises in the machine after it 4s running? Note here ths mazimm and minimun current ratings of all the field rheostats you usad in the test. No. | Make Resistance Currsnt Rating Gans Max. ! Win. Note defects here: (Correct them, if possible) (o) 107 16~AC WAT?-HOUR METER CALIBRATION _. Procedure:.- 1. Test by the indicating instrument method, a watt~-hour meter at loads rangine from zero to normal rated value of the meter. Include readings for "creep" also, if there is any. In making connections include a line switch and properly protect all meters. Data: Tabulate all observations and other data neatly on a standard data sheet. Curves Plot a curve showing the relation between the correct energy as obtained by the indicating instruments as ordinates, and the values obtained from the meter as abscissac. Follow instructions given in the general directions. Questions: Answers to questions 1~7 inclusive should be approved before start- ing the test, the remainder to be answered in the final report. 1. Explain the difference between power and energy and their units. 2. What is meant by (a) the test constant; (b) the watt-hour constant; (c) the watt-second constant; (d) the register constant? 3. Give detailed directions for obtaining the constants of a meter at different loads. Show how to adjust the meter to the correct test constant. 4. What would be the result if friction were not compensated for? Explain how this compensation is accomplished and adjusted. What happens if there is over compensation? 5. Explain the construction and operation of the Sangamo meter. 6. Explain the action of the induction type of watt-hour meter. 7. Explain why meters of the commutator and Sangamo types can be used on alternating current circuits. 8. Explain the phase angle or powor-factor compensation. (c) #16-AC Questions contd. 9. Show how polyphase meters are construted. 10. Discuss the rotating standard, and the calibrated resistance - methods of watthour meter testing. References: Slectrical Meterman's Handbook. Trede Circulars. Jonsky ‘Electrical Meters". _ Shepard & Jones "The Watt~-Hour Meter". Dawes pp. 51-75 Karapetoff pp. 36-171, Vole l (a) ~ #6-ac 109 (e) Station: Observed Calculated Watthour Meter i ' Stand. Watts { Velt Meter | , i : : Lt i Volts: Am. i# ,; Am. Watts , Accur- Disc.] Seconds) “Pest.; Read, Ki Cory K,k/S ' acy Rev. $ Const. | 4 4 rect R # Ks { —_ ! t : j i t i i i 1 t i i ¢ K = Multiplying Factor. Approved: Expt. # ‘Title: Date Diagram of Conmections: Sketch neatly with pencil on a graph sheet the connections as actually used in experiment. Anvarstus: Note name plate data of all machines used: Station # Name | Make Number Type Form ee i — Volts | Ampereas KW. L H.>. | Frequency { Snead Phase Instrumsnts: Note makes, number, ete., of all motars > i , instruments, and miscellanccus aquipmant used. Meter, Make Number | Model Type Range Capacity | Remarks Articis Nomoer Description : 4 Expt. _ Title Date Inspection: This should be made for every experiment performed, defects noted and corrected whenever possibls. l. Is there sufficient oil in tne bearings? 2. Are the brushes badly worn? Incorrectly set? &. Is commtator rough or pitted? 4. Doss armatura turn easily? 5. Are all connections corract? 6. Are couplings or b21t24 comnections proparly mad3? 7. Is machine clear of tools and forscign particles? 8. Have your wiring inspsct3d and OK'd by instructor 9. Do oil rings turn and provide sufficient lubrication after machins is running? 10. Ars there any def2cts, and any unusual noises in the machine after it is running? ll. Note here ths maximum and minimum current ratings of all the field rheostats you ussd in the test. No. | Make Roasistance Current Rating Chms Max. Win. Note defects here: (Correct them, if possibdis) (bo) 110 #L7-AC BOOST & LOVER TEST ON AN INDUCTION ReCGULATOR Procedure: . 1. Turn the hand-wheel of the regulator, after blocking the brake open, until one of the limit switcnes just opens. Commect the primary leads (A,B,C) through line switches to the 110V A.C. source and take readings of voltage tetwsen each of the primary lings (A,B,C) and each of the secondary lines (A',B',C!) for a series of positions of th? regulator gear sector ranging from th; open position of ons limit switch to that of the other. Do not allow the s3ement to travel bayond the point where it just ovens ths limit switch. 2- Connect the regulator, together with its primary relay and resistance, according to the wiring diagrams on the blus-print provided with the test. Operate the primary relay by hand to change the voltage. Then release the contact lever and observe the action of the relay in correcting the voltags. Record what you observ. Test the limit switches by allowing the segment to move wmtil it opsns one of the limit switches and the motor stops. Jf the motor fails to stop when the limit switch opens, pull the line switches immediatoly to prevent ovsr-travel and breaking of the switch. 3. Cornmect a water rhsostat to the load side of the regulator across the same phase to which you have connected the relay, and observe the action of th relay and rogulator as ths load is thrown on or off. Record what you observe. “a Data: Tabulate all observations and other data nsatly on a standard data shest. Curve: Plot the regulator characteristic curve on a standard sheet, using secondary velts as ordinates and positions of the rotating segment as abscissas. Draw also the line representing the voltage which is held constant by the regulator in normal operation. Follow instructions given in the general directions. Questions: Answers to questions 1-2 inclusive should be aporoved before start- ing the test, the remainder to be answered in thse final report. 1. Discuss the theory and operation of an induction regulator. 2. State and discuss some of the applications of induction regulators. a 3. Explain the operation of the primary relay. References: Collins pp. 224-225. Westinghouse 5137-~B Regulator Wiring Diagrams. Dawes pp. 275-278. (c) #v7-ac 111 Station: = Hand Volts Wheal Tarn Primary { secondary To. A-3 B-C 1 B-¢ Ay: Atogt A'-O' | BIC! Ay ene t ~ ; t + t as $ i j | | _ nenaineanienl (4) Anvrovad: Expt. # + Ww Title: Date Diagram of Connections: Anvaratus: eee eed connections as actually used in experiment. Note name plate data cf all machines used: Sketch neatly with pencil on a graph sheet the Station ¢ | Name Make Number Type Form a 4 Volts | Ammeras KW. f)|OUD. Frequency | Snesd Phase | _ Instruments: Note maks, number, etc., of all moters, instrumoants, and Tiscellancous squinmant used. Meter, Make Number | Modal | Type | Range Capacity Tomarks | 7 “Article Numooar heserintion | ! : Expt. Title _ Date Inspection: This should be made for every experiment performed, defects noted and corrected whenever possibla. 1. Is there sufficient oil in the bearings? 2. Are the brushes padly worn? Incorrectly set? 3. Is commetator rough or pitted? 4. Dose armatur3 turn sasily? 5. Are all connections corract? 6. Ara couplings or b2lted connactions properly made? 7. Is machins claar of tools and forsign particiss? 8. Have your wiring inspected and OK'd by instructor 9. Do oil rings turn and provide sufficient lubrication after machine is running? 10. Are there any def2cts, and any unusual nois3s in the machine after it is running? , ll. Note hears tha maximum and minimum current ratings of all thse fisld rheostats you us3sd in the test. No. | Mate Roasistance Current. Rating Girs Max. Min. Note defects hare: {Correct them, if possibile) (b) il2 « #18-AC CURVE TRACING WITH TEE OSCILLOGRAPH ’ Procedure: l. Using the optical method, obtain voltage and current curves of a synchronous motor under the following conditions: (a) Field excited for wity power factor. (») Field under-excited. (c) Fiesli over-excited. Connect the motor windings Y and take voltagz2 measurements from line to nsutral using tie line in which the current curve is taken. In each case msasurs the powsr input with wattmeters and calculate the power factor. Chack the results with a vower-Zactor meter and also with th? curves. 2. Obtain curves of a tracnsformar under the following conditions: (a) “ita secondary on ope: circuit obtain the curves of primary voltags and current and sscondary volists. (o) With sacordary loaded non-indz actively obtain curves of primary and sscondary voltaze and curri2nt. (c) With szcondary connect2d to ths orimary of a sacond trans- former (secondary of socond transformer on som cirenit) obtain curves of primary and secondary roltag3 and current. (d) “ith the secondary of the second transformer loaded non- inductively, odtain curvss as in (c). Data: Tabulaté all observations and other data nsatly on a standard data Cusstions: Answers to questions 1-4 inclusive should 52 approved before start- inz the test, the remainder to be answ2red in the final report. wh “hy must the moving parts of an oscillogrann de very light in JQ 8. Expiain with a diagran, the moving coil or Dudéal t-me of oscillograph. 3. Also the lron-strin or Blondel tyna. 4. Also the hot-wire or Irwin typa. 5. Describe all the sssential features of the General Plectric oscillcegraph. 6. Descrive all the essential fsatures of the Westinghouse oscillo-— graph. 113 #18-AC Questions, sonttd. 7. ‘Explain the results of procedure (1). 8. Explain the results of procedure (9). Refsrances: r Edescumhe pp. 169-179. Std. Hdbk. Sset. 3, 261-270. Foster po. 50-54. Tr.Cire, GE. & others. Masnuss3on Chap. VIII Dawas pp. 72-75. Karan atoff po. 210-228, Vol.Il. (a) Expt. # Title: Date Diagram of Connections: Avvaratus: ad Station # Sketch neatly with pencil on a graph sheet the conmections as actually used in exveriment. Note name plate data of all machines used: Name | Make Number Type Form od Volts | Ameras K.W. uP. Frequency | Spesd Phase i Instruments: Note make, number, etc., of All meters, instruments, and miscellanctcus equipment used. Meter, Make Number | Model Type Rangs Capacity Remarks — 4 } t . mand ee ote anol peel Articie | Wumber 7 Doscrintion Erticis (sor 7 Dsseription | — ; ‘ ewe ne te nee game ee om aaa! t (a) Expt. Title Date Inspection: This should be made for every experiment performed, defects 9. 10. il. Are couplings or b2lt24a connactions proporly mad2? noted and corrected whenever possivla. Is there sufficient oil in the bearings? Are the brushes badly worn? Incorrectly set? Is commutator rough or pitted? Doss armatur? turn sasily7 Ars all connections corract? Is machines clear of tools and foroign particles? Have your wiring inspsctod and OK'd by instructor Do ofl rings turn and provide sufficient lubrication aftor machine is running? Ars there any defects, and any unusual noisze in the machine after it is running? Notes here the maximum and minimum current ratings of all the field rheostats you used in the tos8%. No. | Make Resistance Currsnt Rating Oxns Max. Min. Note defects here: (Correct them, if possible) (b) 114 219--AC | TRANSTORYVER CONNECTIONS Procedur?: (a) Three. to Two-Phase Transformation Using ths Seott-conns eticn connect two trans?ormers through lins aa vu c switchss to a thrs3-phas? sourca so as to odtain a two-nhase source on ths s?condary sid:. Me22esur2 and riecord all voltag3s on Soth th thrse-phass and two-phas3 circuits. (b) mwo to Six-phas> Trans‘ormations Using the connsctions of (a) to supnly the two-phase sources, connsct up two other transformers according t> Fig. S11, pn. 264, Ma pmusson, ortte ting ths neutral. Connect the high and low sidss in such a manner that the six-phas2 voltares can 62 msasured. Mrasure ani record the voltags across 3ach of th3 six phas3s, ani alse, as a ch3ck, measure the diamstrical and th3 delta voltaces. Show and sxplain all ths connections in th2 report. Data: Tabulats all data neatly on a standard data sh33t. Draw connection and tonograpnic v3ctor diagrams for 21ch ons. Questions: Answers to quistions 1+5 inclusive should te approved hefore start- ing th: tast. 1. Explain ths throry of transforming thrae-phase nower using only two transformers. What is the principal use of this combination? 2» Discuss tne T-connactions of two transforuers sometimes used on three-phase circuits. 3. Discuss the Scott system for transforming from two to three-phase, and vice versa. 4. Discuss the methods of transforming from two to six-phase, from three to six-rhase, and from three to twelv2-phase. 5. Discuss the use of the ziz-zag transformer connections for a three-wire rotary converter. References: S$. & 7. pp. 167-171. Smith vp. 155-156. G.E. Rev. Yol. 19, pp. 255~258. Magnusson no. 160-160. Dawes p- 2l1il.. Karapetof? pp 466-531, Yol.I; pp. 68-118,Yol-.II. R. & T. yp. 217-223. (c) Expt-# Title: ___Date Diagram of Connections: Sketch neatly with pencil on a graph sheet the connactions as actually used in experiment. Apparatus: Note name plate data of all machines used: Station # Name | Make Number Type Form oer Volts | Armeres X.Y. HP. Frequency | Spesd Phase i. Instruments: Note makes, number, etc., of all meters, instruments, and tiscellancous equinment used. Meter, Make Numbor | Model Tyos Rang? Capacity Remarks | | | Article umo2r Deserintion {a) “Expt. Mitile Date Inspection: This should be made for every experiment performed, defects noted and corrected whensaver possibis. 1. Is there sufficient oil in the bearings? 2. Are the brushes badiy worn? Incorrectly sot? 3. Is commtator rough or pitted? 4. Dose armatur? turn zasily? 5. Ara all connections corract? 8. | Ar2 couplings or pelted conn3actions properly mad2?_ 7. Is machine clear of tools and forsign particiss? 8. Hava your wiring inspscted and OF 'd by instructor 9. Do oil rings turn and provide sufficient lubrication after machina is running? 10. Ars thers any defects, and any unusual nois3a in the machine after it is ramming? 11. Note hare th? maximm and minimum currant ratings of all the field Theostats you us3d in the test. No. | Make Resistance Gurrent Rating Cams i Max. Min. Note defects here: (Correct them, if possible) (b) 115 #20-AG TRANSTORMES CONNTCTIONS. Y-DELTA & DULTA-Y Procedure: i- Y-Delta, Y-Delta- l. Connect the primaries of sech of two banks of three transformers Y and their secondaries in deita. 2. Comsct the Y-connectel primaries of the two banks in parallel to a 110-volt, 3-phas2 supply. 2ct an apex of the dslta-connsctad secondary of #1 bank with the delta-conn2ct3i s3:condary of #2 dank. 4. Measure and rscord the primary and ssconiary voltaze across each phass, across 32¢h transformer and also batwaen tho remaining non-connzeted 2s of tha d2lta-connset2d secontirtss of both banks. 5. if ths voltace b3twsen an apex of on bank and that of another is zero thess two points may bs connect2d. I+ is thon nacessary however to acain chock the voltass b2tw2en the two remaining an2xes bofers thes? may 63 conmn3ct2d, Record this voltag3. If it is now zero, th? two apexes may )2? connect?i and the two hanks may b3 varallaled, oth:rvwise thoy may not. Ti. Delta-dslta, Y-Delta. 1. Connect both tha primary and secondary of on bank in dslta; the vrimarv of ths sicord bank Y and its stcondary dslta. Choose th2 propsr tios so tuet the sides to b number of turns and transformation rai g v parallzied hav? ths same veltase values. 2. Fellow instructions 3-5 of Part I. 1. Comnect the primary of the first bank delta, and its sscondary Y; also, connect the primary of the sacord hank Y ani its secondary d2lta. Choos? ta? prover mumpar of turns and transformation ratios sec that the sides te »3 yarallaled hav? the sane voltaz>: valuis. 2. Follow instructions 3-5 of Part I. Data: Tavulate ail observations neatly on standari data shest. Draw to scale on standard curve naper the vector and connection diagrazs illus- trating the existing conditions in both primary and secondary of each transformer hank for sach of the three above connections. Use designations similar to thos2 on pp. 447-457 of ths Journal of Wlsctricity, Power & Gas of Nov. 11, 1911. In the report show why the two banks can or cannot be paralleled and explain the diagrams. (c) ary te oO Questions: 1. Diagram the four msthods by which the primariss and tne secon- daries of thrze transformsrs can be combined for thre2-phase transforma- tion, and explain ths voltage ratio obtained frem cach, in terms of ths turn ratio. 2. Diseuss the rilative advantages of the different connections. a Discuss the advintagss 2nd disadvantaces of threa-phass trans- form3rs as compared to thre: singl3-phas3 transformers used for the same purpose. Discuss ths methods of winding and connicting core-tyo2 and i shril—-tyo2 thres-phas.s transformars. Referancss: Jour. Else. Nov. 11, 1911, po. 447-457. G.E. Rev. Vol. XXKIIT 45, May 1990, p. &74-385, Also April 1916 anj October 1908. Lee “orli Novorbor 11, 1908. 428 ep. 175-224. Zara stoft pp. 466-531, Vol.I; op. 71-118 Vol. II. R. & T. po. 217- 202. Expt. # Title: _ Date Diagram of Connections: Sketch neatly with pencil on a graph sheet the cormisections as actually used in experiment. Apparatus: Note name plate data of all machines used: | Name | Make Nutber Type Form a Volts | Ammeres KY. : U.P. Frequency Sraad Phass i : e i Instruments: Note maks, mumber, etc., of all meters, instruments, and miscellaticcus squipment used. Meter, Make {| Number | Modal | Tysa | Ranga | Capacity Remarks detente epenie aes gee Meee mete Sted er Maes emg amine meme rr ge “~~ Te aes | i Article Number vescrintion | Articla “her { Deecrintion fn ; 4 mbna | aad j ae : i nee (a) Expt. mitle | Date Inspection: This should be made for every experiment performed, defects noted and corrected whenaver possibi2. 1. Is there sufficient o11 in the bearings? 2. Are the prushes badiy worn? Incorrectly s2t? 3. Je commtator rough or pitted? 4. Doas armatur? turn zasily? 5. Are. all connections corract? 6. Arz couplings or 631124 connsctions properly mai? 7. Is machine clsaar of tools and forsign particiss? 8. Have your wiring inspsct3d and OK'd by instructor 9. Do oil rings turn and provide sufficient lubrication after macnins is running? 10. Ares there any deftcts, and any unusual nois3s in the machine after it is ruming? ll. Note hore the maximum and minimum current ratings of all the field rhsostats you us3d in the tast. No. | Meice Rosistance Currant Rating | Chins Max. Din, Note defects here: (Correct them, if possible) (>) 117 yel--AC EFFECT OF UNBALANCED LOADS OF TRAYSTORMER BANKS Connect three single-phase ‘transformers star—delta as shown in the diagram which will be furnished. Teke readings of currents in lines X, Y, Z, X', Y', Z', in each ke vhase winding of the delt » a in load rheostat circrits A, B, ©; also voltases vatwoen N-X, N-Y, , NXT, Y-XI, 2-KI, X-Y, X-+-Z, Y-2, XtH¥t, ass m3 SS Kt-Z', Y'-"', Por the Soliowing z conditions: 1. Avoply a balanced load to the transformsrs. 2. With valanc2d load as in (1) open lin? X and take readings. 3. Ramov: the loai from the transformers, open lins X and take roadings. 4, With lines X closed, load phas2 A only, and taxe readings. 5. With load conditions as in (4), onsen line X and take readings. 6. With line X closed, load pn2s2 C only, and take readings. 7. With load conditions as in (&) open line X and take readiness. Plot topographic voltaze vector diagrams for s:ch of the above connections, discuss the resulis, and turn in with the data. References: Karan stoff po. 456-531 Vol.I; po. 71-1198 Yoi.II. R. &T. po. 217-223. Expt.¢ Title: a Date Diagram of Connections: Sketch neatly with pencil on a graph sheet the comsctions as actually used in experiment. Apparatus: Note name plate data of all machines used: Station F Name Make Number Type Form - Volts | Amerss K.W. HP. Frequency Spesd | Phase ae careers ak nee ee teen ae Instrumants: Note maks, number, ¢tc., of all meters, instruments, and miscellanccus equipmant used. Meter, Make Number | Model | Type .| Range Capacity Remarks im ~ — Articia Numoer Doscrintion Articie | [humber j i — . (a) “Expt. Title } | Date Inspection: This should be. made for every experiment performed, defects noted and corrected whenever possibla. 1. Is there sufficient oil in the bearings? 2. Are the brushes badly worn? Incorrectly s2t? 3. Is commtator rough or pitted? 4. Doas armatur? turn sasily? 5. Are all connections corract? 6. Ara couplings or pelted connactions propsrly mad?7 7. Is machine clear of tools and foreign particiss? 8. Have your wiring inspsctad and OF'd by instructor 9. Do oil rings turn and provide sufficient lubrication after machina is running? 10. Arg thers any defects, and any unusual noisse in the machine after it is running? 11. Note here the maximum and minimum currant ratings of all the field rheostats you us3d in the toast. No. | Make Resistance Current Rating Cams Max. ; Min. ~e Note defects here: (Correct them, if possible) (b) 118 E2Q-AC HIGU-TUNSION TRANSFORER TESTS a The following tests will be mai3, two wacks boing tans time limit: {2) O11 Testing, Filtering & Drying. (t) Chscking Transformer Ratios & Calibration of Measuring Voltmeter with the Sphere-Gan. (ec) Insulation Testing. (4) Tnaulator Tasting. (se) Test of Effect on Breakdowm of Using Air and Other Dielectrics in s 3 Ss. fe 8 wv pe (f) Horn-Gap Test. (g) Corona Test. (h) Effect of Frequency & Steep Wave Fronts on Sphere-Gan & Nasdic-Gap Dischare:. Connect the transformer as shown in the diacram, which will be furnishod. Before closing ths line switch »e absolutely sure that all persens are 2 safe distance (at least fiv: f33t) from the high-tension load, and any anvaratus connected to it. (a) O11 Testing, Filtering & Drying. Take a sp3cimen of oi] from the bottom of tha testing transformer. It is to the bottom that most of the moistur?, if th27re is anv, will settis, and kence the oil im its worst condition is most likely to b3 found thers. With the megger test th: rasistance of ths oil in both the 1" and 3" oil cups after adjusting tne gaps for a 0.1" spacing by moans of the gauge. Likewise test the syscimens in both cups by connect- ing to the test transformer ani graduallv bringing the voltage up to the break-dovm value. Eacord all data. The oil should take apnroximately 25000 volts or better. If it is in poor condition it should be filtered and dried. Study the method of filtering and drying and also the means provided for performing this oneration while the transformer is in use. (c) 119 "199.40 (b) Checking Transformer Ratio & Calibration of Measuring Voltmeter with the Syhere-Gan. Adjust the spheres of the gap until they just touch, read the micrometer screw, and then separate the spheras a considerabl2 distance. Bring the voltage of the trarsformer up to a chosen value, adjust the soher? gap mtil it arcs over, at which instant pull the line switch foe immediately. Read the micrometer scrsv again, calculate the distance between sohnsres and obtain ths corrasponding voltage value from the spner 3~gay 2 voltag2 curves. re) Repeat for at least five differsnt values ranging from 10,609 - . 100,009 volts. Plot a curve for uss in subszquent tests, using voltmster readings as abscissae and deduced air-gap voltazes as ordinates. (c) Insulation Testing. Place the sp2cimen to be tested ketween the brass discs provided for the purnos:, and aftor measurinz resistance with the megcor, anvly the voltage gradually, incrtasing it to ths value where breakdown occurs. Make a r3acord of ths break-down voltages for ths various sp2cimens usod. (d} Insvlator Tasting. Measure the resistancs oF tho insulator with ths magzer, then apoly ths voltags gradually and not? the valu3 of voltage and current when corena first appsars, when static discharg?s tak: plac3, and when arc-ovsr sccurs. If th? insulator breaks down, nots tas breakdown voltag?. (e) Test of #ffect of Breakdown of Using Air and Other Dielectrics in Serias. ——. Separate the metal plates of the apparatus one cm. apart and apoly voltags uo to a value just below breakdown. Record this value. Remove tne potential, insert the glass plate in the space between the metal plates, leaving half the space filled with air, apply the voltace previous- ly obtained and note the results. (f) Horn-Gav Test Apply a potential across +h? san sufficient to causes it to break down. Note and explain ths results. 120 f22-AC | (g} Gerona Test. Stretch two fine wires parallel to each other and spaced about one foot apart. Connect one wire to ground and the second wire to the hich-voltac3 lead of the transformer. Darken the room. Bring up tho voltazs gradually and observ? its valu2 whon the corona first appears. {h) Effect of Frequency & Ste2p Wave Fronts on Spher2-Gap and Nezdls- | Gan Dischargs. Adjust one of th> sphere gaps for 40,000 volts (approx. 1.95 em.) by setting the gap and noting ths arc-ove2r voltage. In a similar manner adjust th? nozdl2-gap for 40,000 volts (approx. 6.1 om.) Note the form ation of corona on the ne2dl2 points as th2 voltage? is brought up. Comnect both n22dle- and sphore-~gap in parallel and this combination in sori3s with th2 sscond sphorso-c@ap (s3+ for about 60,060 volts) to tho transformer. Make all leads as diract as possibl3 avoiding all kinks and corners. Bring tht voltsg2? up graduall+ and nets which gaps break down. Maks a bond in the wirs conrnscted to tha first sphere gap (the ons in parallsl wit wher volteze is applied. Remove the kink or corner in the wire so that conditions as before are obtained. Gradually reiuee the distance between the needle points between successive voltaze applications until the needl3-gap arcs over in preference to the sphers-can. Not. this distanc? and the voltaze corresponding to it. References: Karanetoff pp. 1-148, Vol.II. Expt.€ «Title: Date Diagram of Connections: Sketch neatly with pencil on @ graph sheet the cemnections as a wually used in exneriment. Apparatus: Note name plate data of all machines ueed: Station # Name Make} Number Type Form a Volts | Ameres KW. i H.P. ) Prequency Spasd | Phase j i 4 Instruments: Note mako, number, etc., of all meters, instrumants, and wniscellanzons equinmant usad. Meter; Make | Number | Model | Tyce | Range Capacity | Remarks — i sae pecans a tien ceamarntes tewecned Articis | ombar Descrintion Artesia TT Scker™ i ' i ‘ ~ Werte nae rneed {a) Exo te. Title | | ___Date ont performed, defects Be Inspection: mets should he made for every exper , rotted and corrected whenever postiv itn . C4 l. Ts thers sufficient cil in the bearingsT Ze Are the brushes badly worn? Incorrectly sot? Z. Is commitater rough or pitted?__ 4. Doss armatur? tuyn 2esily? 5. Arse all connections corract?_ 6. Ars couplings or belted connections properly raie? Fe Is machine eclsar of tools and forsign particiss? 8. Have your wiring inspect3d and OF'd by instructor 9. De oll rings turn and provide sufficient lubrication after macaing “ds romming? ener 10. Ars there any deftcte, and any unusval nois?s in the machine after it is ramming ll. Note here the maximm and minimua currant ratings of all the field rheostats you used in the tast. bare vas Fn an 4 Note defects here: (Correct them, if possibin) (b) Lal #23--AC INDUCTION MOTOR TESTS ~ BUNTING & LOCKED SATURATION . CISCLE DIAGRAT € ERPPICI°NC’ BY PRONY BRANE Po Risa arian Procesdur3: Fellow in structions as given in Ssction 6 of Factory Testing, Feastinghouse Bl: etric & Mamufacturins Co. Data: Tabulate all observations and other data neatly on a standard data shest. Curvyas: Pict curves on standerd sheets as given in the instructions. 1. Discuss the slin of an induction motor, and its relation to inersasing load. 2. Describe tus differant neathods for measurinz slin directly. 3. “hat determines ths spesi of an induction motor? 4. Explain tas matnods of starting induction motors. 5. Explain the low pow:r-factor found in induction motors, when compared with transformers. 6. “xolain why the secondary is usually the ravolving part. 7. State how to determines the r3sistance per phas3 of a three-phase syvstom, both Y and delta-connacted. 8. Explain the equivalent single-ohase resistance and current of an induction motor. 9. Discuss the Llossss that occur in an induction motor and their relation directly and indirectly to the load. 10. Explain the methods used in determining each of the above classes cf loss. ll. Describe a method for determining the friction loss, as separated from the iron loss. 12. Explain how the torque may be calculated. (c} 122 Qu2zstions contd. 13. Explain how and why the reactive effects of the revolving secondary of an induction motor can be replaced by those of an imaginary fixsd winding, and show what the value of the current in this imaginary winding would b2. _14.. Explain the circle-locus current-vector diagram of a transformer. 15. Discuss the application of this circle-locus to an induction motor, and give complete dirsctions for its experimental determination. 15. Show, by the circle-diagram, how to determine the current, power- factor, torque, slip, input, and efficiency, corresponding to any given output. References: Elec. Jour Yol.Il, pp. 100-107. Factory Tasting W.3. & M.Co. Section 6. A-I.N.E. Vol. XL, April 1921 #4 p. 326-332. Dawes po- 225-304. Macnusson po. 168-210. Lawr snes po. 4435-554, Kerapatoff po. 584-627, Yol.I; pn. 166-186 Vol.II. R. & P. pp. 276-28. (a) Expt.# Diazram of Connections: Title: Date Sketch neatly with pencil on @ graph sheet the Apparatus! + . 2 On comnections as acttuaily used in experiment. Note name plate data of all machines used: it Name Melk Nutber Type Form od | Volts | Ameres Las Frequency Spasd Phasa oe ae Sree _— Instruments: make, number, etec., of all meters, inetrumants, and ijancous squirmant used. Meter, Maks | Nuxber [Model [| Tyse | Range Capacity Remarks ee soma ewes an ia : i t 7 7 ahem ae ene anni aa voreeencttatem toa sonnet ane ete i Si nee aetna GE Oe “> renee? | : ee ne 7 é «ees couse . : Article Numbar Descrintion } citats OT 7 erence on nana Sonera emer aton r= oe Sean eee ete caace ee ia } { : ne sebum geyen saenmcnanesne peered {a) Expt. Tite | Date inspection: ‘This should be made for every experiment performed, defects notod and corrected whenever possivla. l. Is there sufficient of] in ths bearings? & <Are the brushse badly worn? Incorrectly at? 3. Is commtator rough or pitted? 4. Doss. armatur? turn aasily? 5. Are all comnections e¢orract? 6. Ars couplings or b2ltei connsctions properly madet 7. ‘Is machine clear of fools and forcign particles? 8. Hava your wiring inspect3d and OK'd by inrtructor, 9. Do ofl rings turn and provide sufficient lubrication after machine “$s running? an 10. Ars there any 4eftcte, @nd any wrusual noisee in the machine after it is rrming? sion 11. Note here tha maxiorm and minimus currant ratings of all the field rheostats you usad im the fest. No. | Ease Rosistence Gurrant Rat tog Lars 1 ae: bin. Note defects here: (Correct them, if possthie) (b) 123 e4-AC TEERMIONTC VACUUM TUBE CHARACTERISTICS - Comnect the tube as shown in the diagram, which will be furnished. 1. Maintaining the filament current at the normal ratzd value and with normal rated plate voltages, take readings of all maters for a series of values of grid veltage ranging from -50% to 50% of normal plate volta Zee 2. Repeat (1) with the plate voltage 50% above normal. 3. Repeat (1) with the plate voltage 50% bolow normal. 4. Plot charactsristic curves of the vacuum tube using grid-poten- tials as abscissae and plate currents as ordinates. These curves should be similar to those shovm in Fig. 134, p. 151, of "Radio Mginecring Principles". Vacuum Tube Ratings VI-1 Vi-2 Plate Yoltage 3ov. 160V. Plate Resistanca 17000 ohms 5090 ohms Filament Currant 1.1 A. 1.3 A. Filament Veltac> 2.5 ¥ 7 #Y~ Amplification Factor 6-7 6-7 References: "Radio Inginesring Principles" Lauer & Brown, pp. 150-165. 'Thermionic Vacuun Tube", Van Det Bijl, py. 236-265. (c)