claim as my invention: 1. The combination witli a transforiiier coniprising primary and secondary windings, iiieans for varying t.he number of effective 10 tur.-is of one ol! the windings,'and a relay System responsive to predetermined differences in the current traversing the piimary and secondary windings, of means for regulating the relay system iii a@cordance witli the operation 15 of the means. for v rying the winding. a 2. The combination with a transfokmer Fomprising primary and secondary windinicrs, means for varying the number of e:ffecti-ve turns of one of th6 windings, and a relay 20 system responsivo to predetermined differences- in the current traversing the primary and secoiidary windings, of means tor conirolling the influence of the currents traversing the primary and secondary windingg 25 upon the relay system in accordance with the ppe'ration of the means for varying the 'Wind- Ing. 3. Th6 combination with a transformer comprising prirnary and secondary windings, 30 Mean@ for varyink the number of effectivo ttirns of one, of the@ windiiags, and a relay sy,steni i,esponsive@ to predetermined differenc@s in tb.e,current traversing the primary and secolidary windin(,Ys, . of a contact makifi@ de35 vlee for 'controlling the influence of the currents traversing the primary, and secondary -vvindings. upoii the relay system in accordance with the operation of the means for varying th6 winding. .40 The cpmbination with a 'main tr,,tnsformer comprising primary and I secondary, windings, means for varyin the @nuiilber of 9 effective turns of bne of the windi@gs, and a relav s*stem comprising a second transformer 45, and a relay responsive to pred6termined differences, in the etirrent tra@ersing the main yorrimary and secondary windings, of means controllin(y the influence of the currents ti,aversing th@'main prima . and secondary ry 5o windings upon the relay by controlling the connections of the second'transformer in accordance with the o eration of the rneans for p varyino,.the windi 9. 5. 9@h'e combinanelon with a main trans55 foriner comprising primary 4nd secondary m7indings, means for varying @he niimber of effective turns of one of the windings, and a relay system comprising an a-Lito-transformer and a relay re@ponsive to predetermined dif3 ferences in, the current traversing the main 60 primary and secondary windings, of means or controlling the influen'Ce of the currents traversing the main prin-lai-y. and secondary windings upon the relay by controlling the connections of- the auto-transformer iii ac- 65 cordance with t@e opei-ation of the me aiis for -varying tl-ie winding. 6. The combination Nvith a transforiner coiiiprising primary and secondary windings, means for varying the number of effective 70 tur'ns of one of the -windings, and a relay system responsive to pr6deteriiiined differences in the current traversing the primary an secondar y windings, and comprising an auxiliaty transformer, and current transforniers 75 connected to the primary. and secondary windiligs of the auxili'ary traiisfol-mer, of means for controlling the influence of the currents traversilng the first-nan-ied priinary and secondary windings upon the relay systein by 80 controlling the connections of the auxiliary transfornier in accordance witli the opeiation of the means for varying one of the firstnamed windings. 7. The combinatioii with a transf oriiier 85 comprising primary and secondary windings, meanE; for varyinor the. number of effective turns of one of th@'windings, and ,t relay system'responsive to predetermined di:fferences in the current traversing the prilliary and sec- 90 ondary windinos, and comprising an aux. iliary,transform-er and current transformers connected to both primary and secondary windinus, respectively., of means for controlling tli7e influence of the current traversing 95 the first named primary and seconda,ry wind-. ings upon the relay systein by conti-olliii(y the connections of the auxiliary tran8former in accordance with the operation of the means for varying one of the first named windings. ioo 8. The combination witli a transformer comprising primary and secondary windings, means for varyino, the n'umber of eff ective turns of one of the windings, and a relay systen@ responsive to predetermined diiterences io5 in the current trave@sing tl-ie Pril-narv a4d seeondary windings, aiid coiiaprising ,in auxiliary trai-isformer and current traiisformers, connected to both prin-iary and secondary ivindings, respectively, of means for control- 110 ling the influence of the- current traversing the first-liamed primary and secondary windin(ys upon the relay system by varyin a the ratio between the primary and secoiidary windings of the auxiliary transformer in accord- ii5 ance. with the operation of the means fok varying one of the first-named windinols. HENRY A. TRA.VERS.

Reissued Mar. 5, 1929. Re. 17,230 UNITED STATES PATENT'OFFICEO HENRY A. TRAVERS, OF POP.EST HILLS, PExxsyLvANTA, AssIGNOr. TO WESTINGHOU,SE ELECTRIC & XANUF.ACTUP.ING COXPANY, A CORPOru&TION OF PENNSYLVANIA. TRANSFORXER-TAP-CHANGING 3)EVICE. Original No. l,r33O,S63, dated Xay 31, 1927, Serial No. 116,3i4, filedtune 16,1926. App liezi tion for reis sue filed Apr il 21, 192 8. Seri al Zo. 271, 957. My invention relates to't-ransformer-tap- Fig. 2 is a frao,,m@ntary view of a modified changing apparaltus and particularly to.relay form of my invention. 55 systems for protectino, such transformers. One object of niy i@vention is to provide a protective system f@r aii electrical transformer and tapchanging apparatus that shall protect th,.e apparatus from conditions of short circuit within the tyansformer winding. Another object of my invention is to pro10 vide a differential protective sys@em for electric transformers and tap-chanain- apparatus that shall be controlled -i@ a7ecordance with the operation of the tap-changing apparatus. 15 Another object of my invention is to provide ,t protective syste& for electrical transformers and tap-changing apparatus that comprises -an auto-transformer, the conneetions of which sliall be controlled in accord20 ance with the operation of the tap-changing apparatus. An electrical tr-,tnsformer is sometimes provided with a differential relay system connecting the primary and'secondary circuits 25 for the purpose of ai'connecting it from its stipply circuit in the event that the ratio between its input and output becomes of a magnitude that indicates a condition of a shortcircuit betweeli the turns of its winding or a 30 faultto,-round. Whenatransformerhaving the above specified equipment is equippqd also with tapchanging,,tpparatus for vaiying the voltage ratio hetween' the primary and sec()ndary windings, it becomes necessary, to 35 provide means for varying the connections of the relay system in order that such system -shall continue to indicate the true ratio between the transformer input and the outplit. I accomplish the desired result by pro40 viding an auto-transformer in the relay circuit, one windihg of which is energized from the primary circuit of the main transformer and the otfier winding of which is energized from the secondary winding of, the main 45 transformer, three suitable current transformers. of fixed ratio, and varying th-e connections of the auto-transformer in accordance wit-h the changes in the voltage ratio Of the main transformer. 50 In the a@companyinz drawings, Figure I is a diagr@mmatic view of eircuits and apparatus embodying my iixvpn-tion; and My invention comprise8, in general, a main transformer 1 having the -Lisual primary winding 2, a secondary winding 3 and a- tapchanging device 4,,together with a relay protective system 5, embodyino, the details of m inven- 60 y tion. The primaiz winding 2 of the inaain trans- former 1 is (,o nected, through a circuit inter .rupter, 6 to a supply circuit 7. 'The circuit interrupter 6 is provided witli ihe usual trip05 ping coil 8. The secondary winding 3 comprises a pair of parallel windings 9 and 11 th6,t are connected, through an, auto-baldnee transformer 12 and the tap-changing device 4 to a 70 d' 9 nd se'c ondary circuit 13. The win ings a 11 are provided with a plurality of taps 14 to 23 that cooperate with coiatact segments 24 to 33 mounted on a dru-m a4 of the tap-changing device 4. T4e even numbered ta s and 75 cont act segments cooperate with the wmdlng 11, and'the odd numbered tap coiinections andcontact selment,s coo-Derate with the wm@ding 9. TI@e' drum 34 i; connected, by a shaft 35, to a,,motor 36 havin@ a revers'ing 80 switc h 37 coiniieefed to its field wiiading 38. For controlling the direction of rotation of the motor 36, the. i6versing switch 3,7 may be eithe r manually or alitom'itically act . tted by uE ,7Liiis and apparatus whieh are - t 85 stiitible eir(, no shown because they constitute no 'art of the p present invention. The prot.ect.ive system 5 comprises a current transformer 39, irlductiv@ly related to one of the cond.tict.ors of the secondary circuit 13, 90 and connected by conductors 41 and 42- to the seve ral taps 43 to, 53 of an auto-transformer 54, whereby the current transformer 39 is in thesecondar eire it thereol A second cury u rent transformer 56 is connected, by the con- 95 duct or 42 and a conductor 57 to the primary wind ing 58 of the auto-transformer 54. WI @ile an aiito-transformercloes not have sepa rate primar@ and secondary windings, it is customary practice to refer to the- Oircuit 100 inclu ding the entire winding as the primary circu it and to the circuit includ@ing a portion of the winding as the secondary circuit. Ae,- cord ingly, the entire winding'is hereina-fter calle d h primart win(ling and thatr)ortion 105 of the'riinding iiielud3d,in both eir@uits is

2 called the secondary winding. A relay 59 is @onnected betnveen the conductors 41 and 42 ' lel eirguit to the autoti,,,tiisformer in paral 54, across its secondary ivinding. 5 - A driun 61, h,,tving cont,,ict segments 62 to 72 is mouiited on an extension of tl-ie shif-t 35 to cooperate ivitli thetransformer taps 43 to 53, respectiiely. 17lie relty 59 iiaay be of any desii@ed type - 10 thot ope@ateg @N,Iien stibjected to a pi@edetermined currei-it for (i. dee-nite interiral of tiliie a-Ti(I conaprises a, ivindiiig 73 aiicl a contactnalcilig device 74. The c@@tactmaking device 74 is connected by condiietors 75, to i b',Ittery 15 'TC) tiid the tril)l)ing coil 8 of the circuit interrupter 6. The b,.ittery 75 is also coiinected, by condlictors 77, to the motor 36. Assuii-iin,o ,; the device 41 to be ij-Li such positioiitl iat tl@(, tal)s 14 and 15 ire in 20 ciigagemeint ivitli the contact se-ments 24 and 26, rspectii,ely, the i-nain seconclary eirciiit 13 is con-iplet&l'tlii-oiigh the balance-coil 12 and the tap-cli,.ingin@@), device 4, at -"ihich tiii-ie the cc>ntact se(yment 71 on the drum 61 is in eii25 gageiiient wi-@,li tl-ie tap 52 of the ,tuto-translori-ner 54. The prim-,try Ni,iiidii-ig 58 of the auto-transforn-ler 54 is energized in accordanc,- with the ciirrent trivei-sing the ii-iain pi@iIn.iry winclin(-, 2. Nvhile the seconclat-y wincl30 Ing of t]-ie a-Lito-transformer 54 iiieludes all the-",indino-s above the tap 52. The inaiii ,transf-ormer I is iioiv in its position of rel,,itively low volta(,e and liglit secondary current, at which time the number of ampere35 t-Lirns in the primai@y ivindiil(- of the ti,ansformer 54 equals the number a ainpere-turns in its secondary windi ' n(,Y, ivitli the result that the protective system 6 is in a state 'of equilibrium aiid no current tr,,tverses the re40 lay 59. When it is desired to inere-Ase the secondary volta-e of the main transformer 1, the motor 36 is @ner,-;ized to turn the sliaft 35 in a counter-clockwise direction wliieh causes the sev45 eral contact segments 25 to 33 to en(yao-c the tap connecti.on 15 to 23, respectively, i-n a maiiner well known in the art, and to increase the volta(@e and conseqiieintly, the secondary -- circuit in the main transformer 1. However, 50 the current travrsing the primary winding 2 of the main transformer 1 increases faster than the current traversing its secondary circuit 13. Accordingly, if the settino- a the autotransformer 54 were not clianged,. the 55 influence of th@ current transforiner 56 on ihe proteetive sys'tem would over-bala-nee that of the primary-current transformer 39, -with the result that the relay 59 wotild be operated to caii e the eircui.t interriipter 6 to open, 60 thereby cleenergizin-- the main transformer 1. In order to keep the iiifluence of the current transformers 39 aiid 56 on the pi-otective system . 5 equal, it is necessary to so vary the tap connections 43 and 53 that, as the volta(re oi 6,5 the sedondary winding 3 of the, transf' ri@er I 9 is increased, the number of turns in the seegndary circuit of the auto-txansformer 54 is increased, so that the number of aiiipereturns iii the primary circuit of the atito-ti-aiisfornier 64 remaiiis eqtlal to tlie, ntimb(,F of ampere-tlir-ns in its secondary ciieiiit. Tlils is accomplished by cilising ilio druill C)l to sticcessively move the contact seo;ineiits 71 to 62 into eiio-a(rement with tlie@ tip conil(@ctioiis, 52 to 43, r@es5lectively, in accoi-dance ii-itli the i-novement of the druni 34 and the contact se,,,-ment carried thereby. Uncler noi,nial operatin(, conditions, tli(, auto-transforiner 54 remains in L state of b,,tlance or equilibriul-n, ,incl the r(,,I,,iy 59 so rem,,tiiis deenei-gizecl. - Ilowever,' shoulci I sliort-circuit occur betiveen tlie turns of- the prin-iary Nvinding 2 or sceoiicl,,.ii.-v in iiierease in the imount of tl-ie pr' iiii,@iry current traversin- tli6 circuit '@' @A-oiilcl oceiir. b@) iiliile the ctirreiit travei,siiig the cireiiit 13 wotild not inereise -propoit@on@@tte]N-. Thus a voltage is inducecl a@ the teriiiin@ils of the secondary wincling of the atito-transforiner 54 by the etirrent flowin(r in the pi,imaj.-v -%vindin- due to the ctirrent transfoi-iiiei5(,i, @vhicli is greatoi, than the voltL(Ye iiidtlcpd qt the teri-nin,,tls of the secondary iN,inciiii@., cltic,, to the current transforiner 39. The result 6-F this is that as there is no loilger bqlance a @)5 resultaiit volta(ye is ippliecl to the rela3, 59. Accorclinglyi tl@e rolay 59 is energized to close its contact-mal@:ing de.Ni@e 74, thei,el)y actuiting the tripping coil 8 to open the eirellit interrupter 6. 10(li '@Vlien it is desired to i-educe the secondiry voltao-e of the transformer 1, the shaf t 35 is turne-d in a clockwise direction, Nvhich eaiisos the contact se--ments on the di-ums 34 and 61 9 @7 @'o en age their cooperation t, tp connectioiis i o,- ) in t reverse order. However, the niiiiiber of ampei@e-turns in the pi@imai-y cii-eiiit of the transforiyier 54 is ',tl-@vays iiiaintained eqtial to the number of seconclary iml)eretui-lis, provided that no short-circuit exists betweeii i ii@) the turns of.the main primai@y and second,,ti-S ivindin(ys 2 all(I 3 i,espectively. Referi-ing to Fi-. 2, I bave shown t iiiociitn fied form of m invention in which the rela y 59 is connected bptween the conductors 42 an(I 1 i,) 57; that is, across the current 'transfoi-mei, connected to the primary cii,cuit of the trai-tsfornici- I., This form of my invention i s otlierwise similar to that:@how@ in Fig. 1. It will thus be seen that I lilve provided a 320 relav protective system for transformers havin- tap-changin- apparatus connected tliereto'ihat is characterized by having auxilial-y 'ap-ebangino, means for controlling the connecti6ns of an auto-tra@nsformer, such tlaat 12,-, the i-atio of its pyimary and secondary ainpereturns remains equal, regardless of chano.,es in the ratio of the ma' :n primary and secondary currents of the protected trans. former. 130 7 0 j

It is to be understood that such changes in the arrangement and@ connection of the componeiit parts of my invention may be made as will be '@vithin the scope of t@e appended claims. I