A Cathode Ray Power Diagram Indicator Citation Poole, Fred Lloyd (1917) A Cathode Ray Power Diagram Indicator. Bachelor's thesis, California Institute of Technology. doi:10.7907/s2qe-b943. https://resolver.caltech.edu/CaltechTHESIS:07082024-224158768 Abstract No abstract. Item Type: Thesis (Bachelor's thesis) Subject Keywords: (Electrical Engineering) Degree Grantor: California Institute of Technology Division: Engineering and Applied Science Major Option: Electrical Engineering Thesis Availability: Public (worldwide access) Research Advisor(s): Unknown, Unknown Thesis Committee: Unknown, Unknown Defense Date: 1 January 1917 Record Number: CaltechTHESIS:07082024-224158768 Persistent URL: https://resolver.caltech.edu/CaltechTHESIS:07082024-224158768 DOI: 10.7907/s2qe-b943 Default Usage Policy: No commercial reproduction, distribution, display or performance rights in this work are provided. ID Code: 16542 Collection: CaltechTHESIS Deposited By: Benjamin Perez Deposited On: 11 Jul 2024 19:20 Last Modified: 11 Jul 2024 19:21 Thesis Files PDF - Final Version See Usage Policy. 6MB Repository Staff Only: item control page

THESIS A C~thode Ray Power 1>1agram Indioator. Fred Lloyd Poole. l>epartment of Electrical Engineering. THROOP COLLE~ OF TEOHBOLOGY. Pasadena, California. 1917 1 Sixteen years ago Professor Battis J. Ryan began to look for a feasable eleotrosta.tio power diagram in41cator. This search resulted: first, 1n a cathode ray alte:rnating current wave indioator1 and second, 1n a power diagram indicator for high-tension oirouits, also using the cathode ray tube. These were presented to the electrical fraternity in 1903 and 1911 respectively. Its commercial value has since been reoognized by the electrical industry, the most notable example of this is the active study and use of it in the General Electric Research Laboratories. It has become an essential instrument for any laboratory in wh1oh eleotrioal researoh is con.ducted. The cathode ray alternating current wave indicator . represents the only available means tor studyings first. transcient phenomena in transmission lines and electrical maohinery due to switching or to short cirouits1 second, lightning disturbances involving frequenoies of hundreds of thousands of cycles per secondt and third, commutation problems in direct current machinery involving frequencies that var7 between 800 and 8000 cycles per second. The cathode ray power diagram indicator represents the best available means for studying the insulator problem, which 1s one of the most important problems confronting the Electrical Engineer today. It will measure losses in lines, cables, oils and other insulators with 2. the exoeptional a.couraoy of 0.03 watts at 10,000 volts and with an almost absolute sensitiveness to .the wave forms involved. The aocompa:nying diagram shows the construction and dimensions of the cathode ray tube. A direct current potential of about 25000 ·-volts applied between C and A, with C negative,causes a stream of negative electrical particles or electrons to travel at the rate of 50 x 108 cm. per sec. from the cathode C down the slender portion of the tube. Part of these electrons are .intercepted by the diso, 1), and part pass through the hole in this disc, continue in a straight line, strike the fluorescent screen, s, and cause a luminous spot to appear upon the screen. This stream of electrons is composed of negative eleotrio charges and may therefore be deflected eleotrostatioall7. This stream of electric charges constitutes, in reality, an electric current and may therefore be deflected electromagnetically, These two facts form the fundamental facts upon which the practioal application of the cathode ray tube is based. It is interesting to note that we have here a pointer without appreciable inertia, 3 The design of the power die.gram indioator. in the form of problems, will be taken up first • .A supplementary design for the osoillogre.ph will be added thereto. Problem one. nefleot the pencil of rays, which passes through the hole. in u, proportional to the line voltage of 10000 volts or over. The adopted solution for this problem is eleotrosta.tic deflection since it embodies three desirable qualities -- a~ourao;y. facility in manipulation. and ease of construction -- only one of whioh can be obtained electromagnetioal17. The acouraoy of this method depends upon there being no lateral displacement of the pencil of rays, while under the influence of the electrostatic field. This is true because the presence of the glass tube praotioall7 eliminates the possibility of a uniform eleotwostat1o field. If' the ray occupies the same po- sition in the field at all times the defleotion will be aocurately proportional to the voltage. Therefore eleotrostatio plates one centimeter long will be used to influenee the raus preoeden:t to any other influence • .Based upon Franklin and Moliutt, Electrioit7 and Magnetism. the following are oaloulat1ons to determine the voltage necessary on the eleotroste.tic deflecting plates. 4 The path of defleotion is a parabola expressed by • the equation d : d = dietanoe defleoted by the field. t>: distance along path under the electrical influence. S. = ratio of oharge to mass of the electron: 1800 x 104 •e = volts per centimeter in the electrostatic field.. v = velocity of the electron: 50 x 108 maximum in cathode ray tubes. '01fferent1at1Dg _'l)gf _ 1 X 1800 X 104 Xe 2 dD - 2mT . • iv! 502 lol6 4d _ 2Dg X From the dimensions of the tube it will be seen that when this differential reaches the value 4. 75 : 0.158 2 X 15 the deflection will be suffioient to strike the edge of the soreen. 8 Hence = o.158 x 2500 x 1016 = 2.32 x 1011 abvoltirnper em. 1 X 1800 X 104 : 2320 volts per om. Uistanoe between plates is 1.6 inches. The voltage between plates will therefore be 1.5 x 2.54 x 2320: 8850 max or 6250 eff. sine wave volts. This method of deflection is easiest to Q.perate in this case because electrostatic voltage transformation is easier than any other transformation w.hen the voltages ~re as high as these in question. Its eaee of construction over that of electromagnetic ooile is evident. Problem two.. l>efleot the penoil of ra7s at right angles to and subsequent to the above deflection and proportional to the current of .000005 effeotive-sine-wave amperes or more. Thia ourrent is of the order encountered in in- sulator testing. Electromagnetic deflection 1s the only solution for this problem, since the eleotrostatio deflection 1s eliminated .for the reason previously given and the eleotromagnetio field is not distorted by the presenoe of glass. Coils for this purpose may be 11 om, outside diameter e.nd six oeiltimetere inside diameter without seriously affecting the aecuracy of the eleetrostatio deflection. Based u.pon Electrioity and Magnetiam by Franklin and MoNutt, the f::>llo'Vt'ing oaloule.tions determine the number of gauses needed for full deflection of the cathode ray peno11. l>iameter of the screen, 4.75 inohes. Uistanoe from point of deflection to screen is 12 in. 6 the rays are deflected in a ciroula.r pa.th expressed. by the formula d: g'D2h 2mv In which h: gauses and other notation is the same as in the electrostatic formu.la. T>itferontiating with respeot to 1) ,!! ~ ]S!. ~ 6 X 1800 X 104 X h dl) mY 50 X 108 since 6 em. is assumed to be the effective diameter of the 0011. From the dimensions of the tube it is evident that when this reaches 4 • 75 = o.198 the ray pencil will strike 2 X 12 the edge of the screen. Renee the maximum flux will be h . 50 x 108 x o.198 : 9.2 gauses. 6 X 1800 X 104 From Electrioity and Magnetism by Franklin and MoNutt the number of turns necessary may be calculated by the following formula h:~ r in which h • gauses. z:; turns ,, I= abamperes r : radius in oentimetera. 9♦2 : 21t Z X •000005 :t :YJ: X lq•l 3 z: 9 • 2 x 3 x lo 2 11'" X • 000 007 0'1 = 62000 turne, Uee 60000 turns. Oonetruot twelve coils each containing 5000 turns. this will give a large r ange of series, parallel, and series parallel oombinations so that a. good deflection may be obtained for a large range of ourrents, .Prol>lem three. Eltminate the possibility of stray eleotroetatio or electromagnetic fields influencing the pencil or rf;\ys. fhis may be easily solvecl by surrounding that por- tion of the tube with a ferrous metallic sheath. Problem four. Arrange for the most satisfactory operation of the cathode ray tube. First in inportB,nce is to -p:roduoe a unidireetione.l electro- magnetic field whose intensity is variable at will and whose axis is coincident with that of the cathode rey tube. Its purpose is to foous the oathode ra.;ye upon the disc. n, with the result that the cathode ray pencil is the most intense possible and oonsequently the luminous spot is the brightest possible. The bright spot is 8 especially desirable fo r photographic work. The action 0£ this field may be explained as follows: uue to mutual repulsion the eleotrons of the cathode disoharge tend to diverge, but any mot!on of an electron radial to t he axis of the tube is at right angles to t he eleotromagne-t io f ield. The r esult is a foroe whioh st art s the electron in a spiral path. The circular component of this spi ral pa.th a lso euts the electro• magnatio field at right ang les, whioh results in a foroe upon the electron foroing it towards the axis of the tube i.e., bringing it to a foous. Both the strength of the field and the location of the 0011 to produce it have been determined experimentally. A coil having 2500 ampere turns and located in the plane of the cathede givea the best results. Its diameter should be about 7 inches. Explore for the most satisfactory wire to use by try1zig several si2es. #18 :a.& s. wire requires 45 volts when carrying 5 amperes at 65° C. This voltage is too low for con- sideration. #20 B,& s. wire reqnires 66 volts when carrying 3,15 amperes at 65Q c. limits. This voltage is wit hin usable Its weight should be 5.8 pounds. #21 B.& s. wire requires 83 volte when carrying 9 2.5 amperes at 65° C. This voltage is usable. The weight of wira would be 6.9 pounds. #22 B.& s. wire requi~ee 104.6 volts.when oarr;vin.e; 1.98 amperes at 65° c. limit but is usable. This voltage is near the upper. The weight of wire would be 5.87 pounds. Sinoe #20 B.& s. wire gives the minimum weight and the voltage oa.n easily be reauoed to 66 volts by a series rheostat, this size wire was used. The mounting of this coil requires speoial attention sinoe the field it produces is combined with that of the earth to procluoe a resultant field. To seoo.re easy adjustment to compensate for the earth's affeot the 0011 sh9uld be pivoted upon two perpendicular axes. ·' second in importanee is to minimize the effee,t of the eleotrostatie field resulting from the high voltage d1reet current n.e cessary to exoite the cathode ray tube. To do this the exciting voltage will be brought to the cathode ray tube by a.n armored cable, the center conductor being ueed for the negative and the grounded armor being used for the positive. • The field is thus limited to the spaoe between the oenter oonduotor and its a.rmor. Third in importance is to insure the cathode ray tube against damage from :f'lash overs b7 interposing 10 100,000 ohms resist anoe between the oathode of the cathode ray tube and the negative oonduotor of the cable. The most satiafaotory resistances for this purpose are lightning arrester resistance rods. Water in a tube may be used if proper precautions are taken to allow gasses to esaape. Fourth in inpor~=~oe is to prsvent oorona discharge between the two terminals of the cat hode ray tube and. thus elininate the consequent intermitt ant action of the cathode rays. Two methods are oombined to accomplish this. The radius of curvature of the terminals is increased; and that end of the tube, ineluding the terminals, is covered with e. thick j.acket of Problem five. paraffin wax. Provision must be made for recording the indications on the screen, s. There should. be two ways poss ible; photographic, recording and recording by hand traoing. Visual observation should be possible at all times so that ra pidly changing indioations may be watched and :photogra:phe~ at t he critical moment. A lens placed coaxial with the cathode ray tuba, as shown in the diagram, i s used to · t Lu.·ow an image of the figure on the sore en, s. upon a photographic plat e or film, A concave mirror placed next to the lens, as shown l.l in the diagram, 1s used to throw an i mage of the figure on the screen, upon a ground glass where the figure may be observed and tracings made • .A conversion of the power-diagram indicator to an oscillograph, for either V'oltage or current, presents just one problem. Some method must be employed to deflect the oathode-ray pencil according to some known law and at right angles to either the curr ent or the volt age, Investigation revealed a unique, flexible, dependable and direot me·thod of solving this problem. • The ' oathode- ray pencil is given a harmonic motion by a. perfeot sine wave ourve passing through deflecting coils which may be revolved and set at any angle on the cathode-ray tube. The unique part of the method lies in the oombination of reaotances and condensers to obtain the required sine This o.o mbination is shown in the following circuit we.Ye:. scheme. The explanation of the oirouit is as follows: In the first place the voltage across the induotarice L' must be a large part of the voltage of the line between xt inorder to rea.u oe the error of assuming the voltage wave form aerose L' similar to that aoross n. It is a known feot that the third harmonic rarely exceeds 33 l/3% of the fundamental. Also it is a known fact that a re- 12 aotanoe ooil offers three times the resistance to the flow of .the triple harmonic current that it does to the fundamental. This results 1n a reduction of the triple harmonio current thru L' to 11% of the fundamental, sim- ilarly the higher harmonics are reduced to a greater degree. This ourront, upon entering the resonant cirou1t, sets up an oscilating locv,l current which is limited only by the power absorbed in the condenser and in the reactanoe L''• By proper design t his oscillating current is limited to about 6 times the resultant current thru 1'• The re- sult of this current multiplying effeot. which is merely the ouperimposi tion of a large pure harmoni.o current upon a small non-sinusoidal current, is to effect a reduction of the triple harmonic to 11/5 or 2.2% of the new fundamental. But the triple harmonic o·u.rrent passing through the induetanoe L'' passes the condenser with three times the facility of the fundamental and 1>asses the reaotsnce with three times the difficulty of the fundamental, thereby effeoting a final further reduction of the triple harmonio current 1n L1 ' to 2.2/9% or .24% of the fundamental in that oirouit. The sine wave thus obt.ai11ed is sufficiently accurate foz· all purposes. A design of a satisfactory set of condensers and reaotances will be considered next. Sinoe the whole set depends upon an original assumption. four assumptions will be ma.de and the four resulting designs carried in parallel . 13 Th.e design will be used. whioh proves to be the ohea:pest when the :material is puroh~sed. The four designs will be designated as a, b, o, and d. To begin the calculat ion of the sots of condensers and reaota.noas assume a - 10 m.f. condenser capacity. b ... 15 m.f. condenser capacity • - 5 m.t. condenser capacity. 0 d - 3 m.:f'. oondenser capacity. fhe condenser current at 50 cycles using .telephone condensers at 280 effective volts 1s - Io - 280WO -- 280 314 .00001 -... .aa amp. . 314 1.32 amp. ,,000015 : b Io - 280 c.- I = 280 314 .000005 .. .44 amp. 314 .000003 :: .264 amp. d - Io - 280 a X Q X X X X X X X Expressing this current by complex quantities, assuming a power faator of 0.02 for the oondensers, we have - Io - 0.0176 + Jo.a~ b - Io : 0.0264 - + jl.32 a C - Io = 0.0088 + j0.44 d - Io - 0.00628 + j0.264 The ourrant through th~ reaotunoe L' must not be more than 14 IL, b C - 0.224 amp . - IL, = 0.088 amp . IL• = 0.0528 amp . d From bulletin #63, University of Illinois, the nwµber of feet of the proper eised wire tor L'' was found to b~ a - 4800 ft. #20 B.& s. d.o.o. b - 4000 ft. #18 B.& s. d.o.o. o - 6300 ft. # 22 B.& s . d.a.o. d - 8600 ft. #23 B. & s . d.o.o. This wire would weigh a - 16.8 pounds. b. - 21.0 pounds. o 13.3 pounds. d - 14.5 pounds. At some point aooount must be taken of the fact that this resonant circuit mu.st be capable of being tuned for frequencies of 60 oyoles a.id higher. This quality may be obtained most ee.sily by the proper conatru9tion of the inductance ooil, L''• Sueh construotion will be consider- ed here. If the ooils are wound according ·to the dimeneions given in the bulletin $53, referred to above. but consist of two separate ooncent ric pa.rts, onE:l of which may be revolved a.bout an axis perpendicular to their common axis, the resultant 1nduotenoe may be reduced and the curcuit 15 tuned for higher frequencies. fhe design of the inductance ooil, L', remains to be The voltage of 280 across the resonant oirouit oonsidered• will be at praotieall7 right angles to that aoroes the inducts.nae L'. In ord.e r to ha.Ve the voltage aorosa L' o. large part of the total voltage, which is a neeessity. aiad also use a standard voltage for oonvanienoe, a voltage of 340 is used across L' whloh g ives a tot al vol t age of 440, From the bulletin #53 refP-rred to it 1s found that the wire needed for this 0· 0 11 will be: e. b e d ,, n.& s. - 10000 ft. or 6.62 lbs. Ji2a - d.o .o. 1900 ft. or 1,66 lbs. #26 B.& s. d.o.c. - 14000 ft. or 6.4 lbs. ,; C, fi r9 B.& s. d.• o .c. 20000 ft. or 7.44 lbs. 1fo .k' r,r0 B.& s. d.o.o. ... To summarize, the bills of material are, for the sets a - 10 m.f. 15~8 lbs. #20 B.& s. a.a.a. 5.62lbs. #28 B.& s. d.c.a. b - 16 m.f. 21 lb s . JJ. 1a .B . & s. d.e.c • ,i -•. 1.66 lbs ,¥26 B.& s. d.o.o. C - 5 m. i'. 13.3 lbs. f; 22 :B . & s. a.c .c. 6.4 lbs. #29 B. & 3:,. d .c. o • 16 a- 3 m.f. . . 14 .5 lbs. #23 B. & S. di a.e. 7.44 l bs . f 30 B. & S. d.c.o. COHSTHUOT !ON Ur.::TA I:ts . A frame of oak was constructed according to the diagram with such modifications e.s were advi s able during t he work. A broal stable base of box construction provides room for the auxilliary resonant oireuit and serves also ns a photographic box. Two uprights serve to support the. cathode-ray tube and its su pr,lementary apparatus in their correct relative positions. A pieoe of 6 1noh o. d. well oasing was bored out and used; primarily, :for the ferrous metallic sheath., and secondarily. to oarl'y the we·ight of the cathode-ray tube. Preparatory t o cons tructing the· current-defleoting coils thn probable voltages to be dealt with were investiga t ed.• From bulletin #53 of the University of Illinois the inductance of one unit of six coils in series is approximately 1.6 benries. of 470 ohms. At 50 cycles this gives a. reactanoe Tho resis tance a.t 650 O. is 17000 ohms. The im:p eda noe is a p r, ro:x i !nately 17 000 ohms a lso. The voltage will be 17000 x .000005 or .. os5 which is negligible. 17 The following are some i mportant f'G.ots regarding t he constru.ction of the cu.rrent-defleoting ooils. If aff ords great convenience in ao,t ual test,ing to have several current ranges; therefore it was deemed advisable to construot the ooils in seotions. In order to g~t a maximum number of ranges for a minimum n umber of ooils • 12 sections ·..vere deoided upon. The sections should have ap·p roximately equal effect u~on the oathode rays and in addition should draw equal ourrents when o:r,erateo. in pars.llel.i which demands th.at they be eonstruoteo. in the form of "pies"•· If the seotions most remote from the tube were to have their due influence the s pace factor had to be a minimum. These raquirementa were hare to meet. Bakelite impregnation of these ooils was decided upon for two reasons: first, beoause it assisted materially in reducing the space factor and, second, beoause it afforded an opportunity to beoome f am iliar with a recent development in eleotrioal insulation. A very small wire, tL37 .B.& S. enamel, 1u1s used in order to get the required number of turns in a minimum space. The ooil form developed &nd used for these coils consisted of machined discs of hard (half' and half) solder whioh were oovered on the ir l'lut surfa ces with paper and etaeked and bolted on a mandrel. The reas ons for selecting metal for the material are: first, the delioate nature of 18 the wire required a smooth twe-running form, and. second, the Bakelite required a non-impregnable material in order that tha form should not beoome part of the ooil. Tho reason for seleoting solder, in particular, is that it oan be melted from t he coils after the baking prQoesa is completel'l wi thcrnt rench ing a temperature hv.rmful to the coils, for the torrns can be removed in no other way. A me.chine to . :p roperly guid.e the wire on to the coil• form was devised instead of gu iding the wire by hand. T~ere were two r~asone for this: first, the-0r&ticallJ correct meehenical feed gives a more compact coil than haphazard. hand feed; and seconc1, the collectio.n of superfluous Bakelite in the coil form, incident to passing the wire through the Bakelite as it loft the spool, mad0 hand feecling a mat t er of g uess work a.no_ the result dependant upon luck. A motion-reducing meQhanism of levers was constructed · to receive motion from the lathe carriage a.nd deliver it, properly re auced, to the grooved wire-feeding pulley. The ope rat ion of mechanically f ed iing the wire was thus reduced to the aot of reversing the lathe aarriage at each end of an indicated travel. Very satisfactory coils were produced in the above manner. They were then bound together in units of six coils ea.ch. The t wo uni ts u-;e re mounted upon a terminal boatd 1n such a manner that they were on opposite sides 19 of the cathode- ray tube at the position indicated in the diugram . the focussing coil was wound. 1mp1'egnated wtth Bakelite lal'er by layer, and baked.; resulting in an El)xcellent coil. !twas mou..nte d according to the requirements pre- viously stated. In order to increase the machine's use- fulness in experimental work, the ooil was mounted with a vertical adjustment also. All other construction was either a matter of dev-. elopment of methods or finishing up the machine, and is unworthy of any spacial oomment. I Plo(f \ DIAGRAM S co.le I''= 8" • Circuit ,C/ L: a.1 1s A,r- core reactance 7 L' ~ ~ '§ ½ ~I 1 ~ - ~ -~ ~ -....__ \:; ~ '::,...."\ (l 5iae wave current occurs 111 L;a. Air-core reactance , L ~' • Condenser , C. CUfl RENT 5CHEME . SINE - WAVE resonant. Line FOR CIRCUIT 20 BIBLIOGP.il.PllY. Some Characteristiea of Cathode-ray Tubes By J. :e. Minton. G.E. Review Jul7 1916. The Cathode-Ray Tu.be and its P.)'Ypl.ication. :By Tu! .E. Tressler. G. E . Review .Aug. 1 916. Cathode-l1ay .4 lternating Current Wave Indicator. By ll. J. Rya.n. A.I.E.E. Vol. 22 PP• 539 A • I • g . E. Vo 1 . 3 0 pp • l 08 9 .A J.?ower Uiaeram Indic at or. By H. J . Ryan • Uieleotrie Losses With the Cat hode-Ray Tube. By J. P. Minton. A.I.1';.E. July 1915, PP• 162'1. Cathode Raya and their Properties. By J. P. lEin.ton. G. E. Review. Feb. 1915, PP• 118.