[1]3 , 1 6 4 , 7 0 0 United States Patent Office Patented Jan. 5, 1965 C-UR,7@,ENT LIMITIPTG Ck-P@CU3T B'@11,EAKEP, 17t'ITI-l AUMLIA tr@,.Y TCC-GLEI MECIIANISRI-F Au;p,@ist Bo&lenschitz, Ph.@Tadeiphia, Pa., assignor to I-T-E C@r,nit Breal-er Corrr,@iiy, PhiEndelphia, Pa.3 a corp-o- 5 ofFiled Apr. 13, 19-59, ger. No. 806,041 11 Cla!2-os. (Cl. 209-116) This invention is directed to a current limiting c;rcuit 10 breaker which does -not utilize an auxiliary ctirrent limiting means, such as a fuse, wherein initial high speed contact separation for imparting the current limiting characteristic to the unit need not continuously operate against coiitact closing pressure. 1 5 Current limiting circuit breakers have been disclosed in copending application, Serial No. 770,321, filed Oct. 29, 1958, in the name of William Harold Edn-itinds, ,)md en'Litled "Current LiiTiiting Circuit Breaker" no@v issued as U.S. Patent 3,012,118. In the above noted application, 2 0 the untisual action of a current limit-ing nature due to an initial and high speed contact separation prior to operttion of the contact operatin.- mechanism has been fully discussed. Geiierally, the principle of the current liniiting circuit 25 breaker is to cliise in initial bi.-h speed op-,ning of th-- contacts independently of the operating inechanism and before the motion of the operatin.- mechanisin can bo initia'@Ccl. Tlierefore, the contact closing bias from the main operating mechanisni operates on the movable con- 30 tact, and the initi-,d contact openin.- means must work against this bias. Tllis bias is normally derived from some typ-@ of spring me-@ins where;n the force which biases the contact closed iriereases as the movable contact is moved toward a dis- 35 eiigaged position. Thei-efore, a substantial amount of ener.-Y will be required of the solenoid or blowopen circliit or similar circuit, causing the initial contact openin.- independently of the operating mechanisin. The principle ol' this inveiition is to provide a novel 40 coiitact iiiechanisin wherein the required contact pressure bias is provided, blit this contact pressure bias may be quickly overconic after an initial application of force and indep,-ndently of the main operating mec,hanism of the circuit breaker. 45 In the preferred einbodiment of the present invention, the normal circuit breaker operating mechanism is coniiected to the movable contpct through an ti-ixiliary to@@gle m-.ch,,inism. When the toggle is in its latched or ove.,:- 50 center position, th.- toggle spring urges the niovable contact closed through its tog.-le mechanism. VVhen, however, there is an initial force applied to the movable co.it,ict diie to the -,ttixiliary means which is to cause the initial separation of the contacts independeitly of the iiiain operatin@ mechanism, the initial force iieed only 55 throw the auxiiitry toggle over-center whereby it will snap to L collapsed position. Thus, th.e i@litial contact opeiiiii- n-iotion will be provided after only a relativc-ly slight aiiiount of etiergy is derived from the auxihary 6 0 operating mechanism. I The complete auxiliary toggle is carried by a frame in a preferred embodiment. The frame is then connected to and moved by the main operating mechanism belween the contact engaged position aiid the coiitact disengaged 65 position when n-lan-Lial 6peratioii of the unit or operation by the main operatin.- niechanism is required. Accordingly, the primar@ object of my inventioil is to provide a novel etirrent limitin.- circuit breaker wherein initial con@,act niotion is easily obtained independently of the circuit breaker operating mechanism. 7 0 Another object of my invention is to provide a novel structure for delivering a s,,ibstantial contact closing pres2 sure wbich may be overcor@ie by the application of a giveii force for a relatively short time. Anotlier object of my invention is to provide a novel contact presstire ineans for circuit breakers Nvhich can be Overcome by a relatively small aniount of ciiergy@ A further object of niy invention is to provide a novel contact p,,- essi-ire biasing meaiis for current limiting circuit breal@ers which may be operated by auxiliary operating nieans for effectin.- high speed initial contact separation without requiring a substaiit-lal aniount of ener,-y froni the auxiliary mechanism. These a-nd other objects of my invention wifl now becoia-ie apparent from the following description when taken ;n cotiiiectioii with the drILwings, in which: FIGURE I shows a side cross-section-@il view of a typical circuit breaker adapted in accordance with my novel auxiliary operating niechanism. FIGURE 2 is a perspective view of the frame for stipportin@ my novel auxiliary operating mechanism. FIGURE 3 is a perspective view o.L the toggle which forms my novel operatitig mechanism aiid is attached to the movable contact Nvhere the toggle is iii its over-center position. FIGURE 4 illustrates the toggle of FIGURE 3 when in the collaosed positioli. FIGURE 5 is a perspective view of the manner in @vhlch the frame of FIGURE 2 supports the toggle of FIGURES 3 tnd 4, and ftirther illustra@les the manner in which th.- main operating mechanism crank is con-.iected to the frame. FIGURE 6 illtistrates a side cross-sectional view of the auxiliary op@-rating mechanism with the contacts in their closed position ind the toggle iii its over-center position. FIGURE 7 is similar to FIGURE 6, and illustrales the toggle ii its collapsed position as due to a short circuit carr-led by the breaker and prior to the time at wwch the normal operating mechanism operates. FIGURE 8 is similar to FJGURES 6 and 7, aiid illtistrates the maniier in which the contact is moved to a disengaged position through the main operating mechinism whicli moves the frame of the -,uxiliary operating mechanis.,ii. Referrii-ig first to FIGURE 1, a typical circuit breaker is shown therein which comtirises a molded housing 10 havin@ an ot)erating handle 12 connected thereto. Th,circuit brt,,al@er shown has a line terminal 14 and a load term;nal 16 wtiich are inierco-nnected by a conductive member 1,3 which carries stationary contact 20, 1-novable contact 22, pigttil 24 connected to movable contact 22, the trip unit 2@l,, and p,.,-tail 25 which is connected from trip unit 26 to terminal 16. Contacts 20 and 22 are associated with an arc chlite 29 in the usual manner. The trip unit 26 has been illustrated herein as a block, and the details of its construction have been omitted. it will be obvious that trip unit 26 may be of any desired standard type having overload elements or instantaneous trip devices. It is sufecient for purposes of the present invention to understand that the trip unit operates to remove a latch 30 from cradle 32 which is pivotally inounted at fixed pivot 34 wheii trip unit 26 is actuated by predeterm,'@ned fault condition. The cire-Liit breaker operating -iiechanism includes the aforemeiilioned cradle .32 rnd a to,@gle mechanism form@-,d of tcg el; gl nks 36 ' 3@' which drive bell crank 4,3. Tiie bell crank 40 ard toggl(-, li-.ik 33 niay be sce-@i in FIGURE 5 as double m,ember@,. Togple link 36 is pivotally carried on a cc.-itral portioil of cradle 32 by pin tA2, aiid tog@le li-nks 36 and 33 are joined by pivot pin 44. The lo,,ver toggle lir@Ic 38 is then pivotally connected tc) one end cf bell crank 40 by a p@@vot pin A6, and the bell crank 40 :s pivotally mouiiied oxi fiied pivot 43. The main toggle spring 50 for operating th,- aforenie-,itioned main toggle
[2]mechanism is then con-@ected between a porflion oll operating handle 12 and th,- Imee of the toggl-, or pin 4A. In operation, it is clear that so long as latch 30 is latche,d, moveme-@it of operatin@,, handl-, I'@, to the @.gh-t ivill c,,iuse spring 50 to move to the right of pin 42 and thus snap ta-, knee olf the tof,,.-le or p,'@n A4 to th-. ri.-ht. Th@s will c,,luse a rot-,ition of bell crank 40 .n a couiit-@rclockviis-@ Llirection about its pivot 43 to cause a subseqti,-nt contact opening operation, as will be describ-,d niore fiilly hereinafter. In a like mann-,r, the togple can be snapped back to the po.@it-lon show@i, 'che coiatact engaged t)ositioii, by movin-, spring 50 to the lei., of a line joir@ing pin 42 and pin 44. Iii the eve-,it tlat th,- trip ti@nit 26 is operated and latch 30 is removed, th-- cradle 32 wi',l rotate in a counterclockwise direelion under the influence of spring Pr until pivot pin 42 passes to the left of spr;ilg 50, at which poir@t the toggle will again collE,-.ps-- to the rigat to cause the stibseqi-ient contact opening operation. The esse-@ice of the present invention is to provide a novel aux,'Iiary operating mechanisni which may operate th-. contac's to a disengaged position indcpcndeitly of th-- aforemettioned ma;n operatin.- mechanism in a very high specd maiiner so as to impart a curreiit limiting ch,iracteristic to the ititerrupter. This operating mechanisin str@.icture 1-nay be best unclerstood from FIGURES 2 thro-Li,-h 5 whic-h show a fraiiie and an aixiliary to-,-le iiiecha,iism associal,,,d with movable contact 22. More sp-.cii'ically, the movable contact 22 is carried by a rod 52 which has a magnetically responsive portio-@i 54 at the end th--reof which is positioned to move into solenoid 5,',. Note that rod 52 could be mad6-- of steel and in a sirigle piece. The contact rod 52 extends througa apertures 53 and 60 o'L frame 62, as best seen in FIGURE 2. As then shown in FIGURES 3, 4, and 5, a ceitral port-.on of rod S2 receives a pin 6,-l which rides in a pair of slots ) oii either side of frarne 62. Pin C,4 further serves as thpknee of an auxiliary toggle forrr@ed by pairs of tog-l,- links 61.-70, and 72-74 respectively. The upper end of the to.-gle is conipl-@ted by pin 76 whicl@i receives the upper ends of Iiiiks 63 and 70 where pin 76 is carried iii opposing slots 78 and 00 of frame 62, as seen best in FIGURE 5, wwle the lower end of the tog.-le :is completed by pin 82 which receives the lower end of links 72 and 74 and rides in opposing slots 84 and 36 of frame 62, as seen in FIGURE 5. The i-ipper and lower toggle pins 76 and 82 respecti-,,ely are then connected by toggle sp.rings 83 and 90 which lie on the o,@itside of the frame 62, as seen in FIGURE 5. The auxiliary to@gle mechanism is shown in FIGURE 3 where the toggle is in its over-center position, this being the position of FIG",JRE 5. As illustrated iii FIGURE 4, however, th-@ toggle can collapse to the rig' at after being moved past its over-center position, whereupon contact rod 52 is moved bac@,wardly with respect to frame 62 with toggle knee pin 64 riding in slot 66. The final position of the collapsed toggle may obviously be determined, either by the depth of slots 78, 80, 8.4, and 32 of frame 62, or by the length of slot 66 of fran-ic 62. The frame 62 is movably mounted within the eirciiit breaker iri any desired maniier. For example, a pair of an.-le supports, sl-,ch as an.-le support 92 of FIGURE 1, may be provided with a slot 94 which receives inward projections on either side of frame 62, such as inward pro;ectiotis 96 and 98 for the side sho@xr, in FIGURE- 2. The sliot 9,1, is made lon@. enough to car@-y iiiward projections 96 and 98 throii-hout the complete required length of travel of frame 62 when this riember is w-oved by the cii7cuit breaker main operating riechanism with the ma--imtim travel of rod 52 be;n,- determined by stop 99. In order to carry contpct Tol 52 with frame 62 when the frame is -.noved, rod 52 is provided wilh an adjustable collar 100 which receives the inner face adjacent 3,166,700 aperture 53 of fran-ic 52, when frame 62 is moved to the right in the figures. There, is, however, a small dis'uanc-c bellvoen th-,se two members whe@i '-he circiiit brealer is iii its closed position so that toggle sprin,-s 83 and 90 of the auxiliary oparating mechanism may exert the reqtiired contact pressure. As previously described, the frame 62 -is driven by th-- mal@i operatinmechanism through the pivotally rrounted bell crank 40. This constiliction is best seen 1( in FIGURES I and 5 where the lower end of bell crank @O -is prov,'@d@,d with slots, such as s'ot 102, which receiv,- projectio-@is oli opposing sides of frame 62, such as prcjeclions 104 and 106 of FIGURE 5. Acec)rdingly, as bell crank @40 is rotated under th-. in15 f'i@,ieTice ol' th-, main toggle mechanism, projections 104 ,)nd will ride witwn the bell crank slots, such as slot IG2, as f.-ame 62 is driven alor@- its longitudinal g-u-ide slot 94, as above described. Iii order that contact Z2 may be quickiy moved loward 20 @i diseigaged posit-Ion responsiv-@ to the occu-rre.,ice of predel@eri-nii-ied fault conditions, the co@ilact rod 52 mqy b-, i,-,it'ally riioved by either the blow-off force on the c--,@i'lact, or by the auxil;ary solenoid 56, or by both, indeptndently of 'Lhe main operatin.- mechanism. Thus, 25 ec.,@idi-icLor 18 oi. FIGURE 1, contacts 20 -,nd 22 and pigtail 24 fo:m a Ushao@-d c,,irrent path which, under the irfiuciice of predetermined I'ault curr,r@ts such as very rorj;dly ris'n.- l@ault etirents, will effec'L a blow-o',T force tendin-. @to drive colitact 22 to the rig@it. 30 Furthermore, solenoid 56 may b-, provided with an energizip,- c,.rcuit sch-,mat'ically - 111,,istrated by blocl,, tOg vvhich is associtaed in some mann-@r with pigtail 24, @as illustrated by the dotted lines, or with one, of the other portions of the circuit breaker which will conduct a pre35 delermined fault current. As was the case with the blowoffcircuit, when the fault leurrent is of some pred-@termined na,,Ure wh;ch may be beyond the interrpt;n,LL-ility of the trip unit 26, solenoid 56 will be eiergized to altract magnetic portion 54 of rod 52 and cause a 10 rapid motion of movable contact 22 to the right substantially prior to the tirne th,,it ti,,- operation of trip unit 26 will caus,- operation oj' the main operating mechanism so as to impart the desired current limiti,@ig charac'@er to thebreal-,er. 45 One oj' the main advantages of my novel operating mechanism is that a -relatively small amount of en.-rgy is required of the auxiliary op@-,rating means which is to initially move the movable contact to ta disengaged posill.on. This ooeration is best understoood from FIG50 URES 6, 7 and 8. Referring first to FIGURE 6 which shows an enlarged view of the auxiliary operating meebanism and contacts of FIGURE 1, it is clear that ftame 62 will be held in a position determined by the main operating mechanism so 55 that the over-ceiiter toggle formed of links 70 and 74 will tend to drive the kiee formed by pin 64 to the left, to cause a substantial contact engagin-@ pressure belween movable contact 22 and stationary contact 20. When, however, a force is appl,'@ed to contact rod 52, as due to 60 the blow-of action of the contact, or the energization of solenoid 56, or both, the contact moves to the right against the force of tov@l,- spring 90 (as well as spring 88 on the other side of tne fram,- 62) to exte-@id these toggle springs only until knee pin 64 moves to the right of the I'ne join65 ing upper pin 76 and lower pin 92. At this point, the tog,-le is broken @and the contact 22 will very rapidly continue to move to the disengaged position of FIGURE 7 as the toggle collapses to the position of FIGURE 7. Thus, the only energy required of the auxi-iiary mecha70 nism is the e-.iergy needed to drive the auxiliary toggles over-center as contrasted to recuiring a power for continuously @perating against a c-ontintious bias sucli @@s @C osing toggle spring 50 wh,' h continually exerts a contact el force until the main operatirg rr@echanism operat,-s. 75 Once the position of FIGURE 7 is reached, the main
[3]5 operating mechanism, which was released through its trip unit 26 of FIGURE I by the same fault that actuated the initial contact motion of rod 52, "catches-up" to rod 52, and continues to move the rod 52 through frame 62 to the fully disengaged position of FIGURE 8. It Avill be noted that the frame 62 continues to move after rod 52 ciigages stop 99. This permits the auxiliary toggle links 70 and '/4 to be reset since the center pin 64 is stopped, but upper pins 76 and 82 are still moved to the right. Since the resetting operation is automatic, it is only necessary to reset the main operating mechanism by resetting cradle 32 by means lot shown but well known to the art, and the breaker can be reclosed to the positioii of FIGURE 6. When this reclosing occurs, collar 100 and rod 52 will move with respect to frame 62 from its engagin- position of FIGURE 8 to the spaced position of FIGURE 6 to permit the toggle spring 90 to supply the required contact engaging pressure between contacts 20 and 22. Although I have described preferred embodiments of niy r@ovel invention, many variations and modifications Nvill now be obvious to those skilled in th6 art, and I prefer therefore to be limited not by the specific disclosure herein but only by the appended claims. I
