US2472625A - Electric circuit breaker - Google Patents

Description

2 sheets-sheet 1 Fig. 5.

S. R. SMITH, JR

ELECTRIC CIRCUIT BREAKER June 7, 1949.

Filed lay 23. Fi

Sdrwey F?. Smith by fw/ 511W H15 Attorney.

June 7, 1949. s. R. SMITH, JR

ELEcTRIc CIRCUIT samen K 2 Sheets-Sheet 2 Filed lay 25. 1944 r'wventor`. Sidney R. Smith Jr?, by )VMC His Attorney.

yPatented June 7, 19149 UNITED STATES PATENT OFFICE ELECTRIC CIRCUIT BREAKER Sidney n. smith, Jr., Pittsfield, Mass., minor to General Electric Company, a corporation of New York Application May 23, 1944, Serial No. 536,872

I extent in the protection of high tension electric Devices of this kind in general comcircuits. prise replaceable fusible means mounted within a suitable holder and they are usually located in close proximity to the high tension conductors as a consequence of which they are relatively inaccessible for inspection and maintenance. Dimculties have been encountered in providing fuse cutouts having an electric fuse convenient for installation and inspection and at the same time capable of being removable and replaceable. In any event, an abnormal electrical condition occurring on a circuit protected by a fusecutout will destroy the fuse and hence require replacement thereof. Although recent experimentation and research have reduced thel cost of the replaceable elements, nevertheless such cost is still appreciable and it would be desirable to provide a fuseless cutout which would automatically interrupt the circuit under abnormal electrical conditions and yet wherein it is unnecessary to replace any elements after the protective operation of such cutouts, as is necessary with the fuse cutouts of the prior art.

It is an object of my invention, therefore, to provide a new and improved circuit breaker adapted to replace the fuse cutouts of the prior art,

It is another object of my invention to provide a new and improved fuseless cutout which is simple and compact, economical in construction, which gives an immediate and reliable indication of the actuation and condition thereof, and which may be used in connection with prior art housings for fuse cutouts.

It is another object of my invention to provide a fuseless cutout of the vacuum type which may be used in place of the fuse cutouts of the prior art.

Further objects and advantages of my inven- 3 Claims. (Cl. 20o-113) tion will become apparent as the following description proceeds and the features of novelty which characterizes my invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.

For a better understanding of my invention, reference may be had to the accompanying drawings in which Fig. 1 is a view of the upper portion of an electrical device with which my invention is associated; Fig. 2 is an enlarged sectional view of a fuseless cutout of my invention in the closed -circuit position; Fig. 3 is a view looking at the inside of the door or cover of the housing of the fuseless cutout of my invention; Fig. 4 is a partial view similar to Fig. 2 illustrating the fuseless cutout in the open circuit position; Fig. 5 is a sectional view similar to Fig. 1 with the housing removed, of a modification of my invention, and Figs. 6 and 7 are partial views of the modication illustrated in Fig. 5 showing different operating conditions thereof.

Although my invention is adapted for use wherever fuse cutouts of the prior art have been used, either supported'from a pole, cross-arm, or the like, I have chosen to illustrate my invention as supported on the insulating bushing of an electrical apparatus such as a transformer or the like.

Referring now to Fig. 1, the transformer I0 is illustrated as being provided With a cover I I upon which is mounted a high voltage bushing I2 having a terminal with a suitable extension I3 Lsee Figs. 2 and 4) at the upper end thereof. Mechanically supported from the terminal extension I3 is an electric circuit interrupting device I4 embodying my invention.

Electric circuit interrupting device I4 preferably comprises a housing I5 which may be substantially identical with the housing disclosed in Hermann Patent 2,163,398, granted June 20, 1939, and assigned to the same assignee as the present application. Housing I5 is preferably formed of porcelain or other suitable insulating material and is provided with an integrally formed electric creepage and gas barrier I6 disposed between stationary contact assemblies I1 and IB supported in spaced relationship in housing I5.

The contact assembly I1 includes a line terminal I9 adapted to have a line conductor or lead fastened thereto by means of a suitable clamping screw 20. This line conductor or lead.

not shown, may enter the housinglor casing I5 through an opening 2I (see Flg.'1) which opening is in alignment with terminal I9. Contact assembly I1 further includes a contact nger 22 backed up by Vmeans oi' a' spring strip 23 which serves to press the contact nnger 22 downwardly. In addition, contact assembly I1 `includes a terminal clip '24 which is arranged to receive the ilanged terminal cap 25 of my improved circuit interrupter which is similar to the terminal caps of the fuse holders of the prior art. The terminal clip 24, the spring strip 23, the contact linger 22 and the line terminal I9 are unitedto form the unitary contact assembly I1 which is suitably cemented into a recess 29 in the upper rear wall withinhousing I5.

The lower terminal assembly I3 really comprises a hinge bracket 21 which serves as the lower terminal contact of the circuit interrupter and forms an integral part of the electrically conductive bolt 29 which extends outwardly through an opening 29 in the rear wall of casing or hous- V ing I5 and which is xedly anchored in the opening 29 by means of suitable cement indicated at 39. The outer end ofthis bolt 28 is threaded for the reception of a clamping nut 3I and a lock washer 32 so that cutout housing I5 may be mechanically supported from terminal extension I3 of transformer I9. With this arrangement the hinge bracket 28 which serves as a lower contactof thel circuit interrupter of my invention, is electrically connected to the transformer terminal extension I3. Preferably the live exposed portions of terminal extension I3 and conductive bolt 28 are covered by a suitable insulating shield 33 which may be similar to that disclosed and claimed in Patent No. l2,409,042, issued October 8, 1946, to Benjamin R. Hermann, and assigned to the same assignee as the present application.

It should be understood that as far as my invention is concerned, housing I5 might also be constructed in accordance with the housing disclosed in United States Letters Patent 2,081,813, granted May 45, 1937, upon an application of Benjamin R. Hermann and assigned to the same assignee as the present application.

The open side at the front of housing I5 is closed by means of a door, or cover 34 preferably constructed of insulating material and having generally the same shape and design as the doors or covers of enclosed fuse cutouts of the prior art, whereby this door and the apparatus associated therewith may replace the doors or covers of the prior art constructions or at least be interchangeable therewith. This door 34 supports on one face an electric circuit interrupter generally indicated at 35 and described in greater detail hereinafter. On the other face of the door or cover 34 there is formed an eyelet handle 36 which may either be grasped manually or engaged by a suitable switch stick (not shown). The circuit breaker or interrupter 35 when in the closed position completes the electrical circuit between contact or terminal assemblies Il and I8, respectively.

Suitably bolted to the lower inside face ofdoor 34 is a U-shaped member 31 having a hookshaped extension 38 for engaging the hinge pin 39 supported by hinge bracket 21. With this arrangement door or cover 34' which, as will be described, supports circuit interrupter 35, is adapted to be pivotally supported by hinge bracket 21 in such a manner that the door or cover 34 may be pivotally moved to either its open or closed position and furthermore bodily lremoved from casing or housing I5 whereupon 'I preferably closed by a flexible diaphragm 4I fastened to housing 49 by means of a suitable seal. The upper end of housing 49 is closed by a metal cover 42 also suitably connected so that glass casing or housing 49 may be evacuated to a high degree of vacuum. Flxedly mounted within the upper end of evacuated housing 49 is ya cup-shaped stationary contact 43. This contact has a hollow rod-like extension 44 which extends out of evacuated housing 4'9. A passageway 45 within extension 44 connects the interior of housing 49 with the exterior so that the housingmay be evacuated to a high degree after which the end of extension 44 is sealed off exteriorly of housing or casing 49 as is indicated at 46.

In order to supportthe circuit interrupter 35 fromdoor or cover 34 rod-like extension 44ertends through an opening 41 in a projection 4'8 mounted on the inside face of cover 34. Any suitable means for rigidly fastening rod-like extension 44 to projection 49 may be provided. As illustrated in Fig. 2, rod-.like extension 44 is threaded so that flanged cap 25, which is internally threaded, and nut 44 may be suitably fastened thereto. Flanged cap 25 is removed so that the rod-like extension 44 may be inserted through opening 41 in projection 4'9, and proiection 48 can-then be clamped between nut 44' and flanged cap 25. Cap 25 connected to rodlike extension 44 forms the upper contact of the circuit breaker which is adapted to be electrically engaged by contact ringer 22 when the cover 34 is in the closed position shown.

Cooperating with stationary cup-shaped contact 43 is movable contact 49 supported on a rod 59 which extends through exible diaphragm 4I but in sealed relationship therewith. It will be understood by those skilled in the art that only a very small movement which may be of the order of al, inch separation between contacts 43 and 4'9 is required to interrupt high currents in a high vacuum. This relatively small movement is permitted by flexible diaphragm 4 I. A suitable disk 5I is mounted on rod 59 within vacuum housing 49 to prevent the arc products from impinging against the flexible diaphragm. The reciprocal movement of rod 59 and contact 49 is guided by a member 52 supported by U-shaped member 31 or, if desired, formed integrally therewith. Member 52 is preferably formed of insulating material or at least the opening therein through which rod 59 reciprocates, is hushed with insulating material.

With the arrangement described thus far, it is obvious that atmospheric pressure will bias contacts 49 and 43 into engagement. I provide a spring 53 which is compressed between member 52 and a washer 54 held on rod 59 by pin 55 which provides a suiiicient force to overcome atmospheric pressure and bias contacts 43 and 49 to the open position shown in Fig. 4.

In order to hold or latch the contacts 43 and 49 in the closed position shown in Fig. 2, I provide a latching means which comprises a current responsive means comprising U-shaped bimetallic element 56 best shown in Fig. 3, a member A5l preferably formed of molded insulation and slidable on rod `50, and a suitable spring means 58.

lSpring means 58 is 4slidable on rod 50 with one end engageable with iiexible diaphragm 4'l, while the other end is engageable with the upper portion of latching member 51. The U-shaped bimetallic element 55 is suitably fastened, as indicated at 59, to door or cover 34. vA sort of roller element 55' onl bimetallic element 58 is adapted to engage a Vprojection Il on slidable member 51 when it is moved to its uppermost position indicatedV in Fig. 2. In this position spring 58 is compressed so that diaphragm. is moved upwardly to hold contacts 43 and 49 in the closed position. One leg of the U-shaped bimetallic element 55 is electrically connected to rod 50 by means of a conducto;` while the other leg of the U-shaped bimetallic element 58 is electrically connected by conductor 62 to U-shaped member 31. U-shaped bimetallic element 55 is very similar to the arrangement disclosed and claimed in U. S. Letters Patent,2,273,764, Salter, assigned to the same assignee as the present application.

With the above arrangement of U-shaped bimetallic element 55 the current flowing throughv circuit interrupter 35 must ilow through bimetallic element 55. Excess currents will cause it to deflect to the position shown in Fig. 4 whereupon roller 56 becomes disengaged from projection 88 and spring 53 then causes relative separation of contacts. and 49 to the position indicated in Fig. 4 with the consequent interruption of the current flowing between terminalv assemblies l1 and i8.

In order to indicate the operating condition of circuit interrupter 35, slidable member 51 is provided with an extension 83 which may be suitably colored in a conspicuous manner. When the circuit interrupter is-in the closed position shown in Figs. 2 and 3 the indicator 83 is moved completely within housing l5 and is not visible. However, upon operation of the current responsive latching means including bimetallic element 56, slidable member 51, and indicator 63 move downwardly to the position shown in Fig. 4, with the indicator. 83 clearly visible. It will be observed that the movement of slidable element 51 is many times greater than thatA of rod 58 and this movement is limited by the engagement of slidable member 51 with member 52, as shown in Fig. 4. The indicator 63 also provides a handle for resetting the circuit interrupter 35. As soon as bimetallic element 56 has cooled sufficiently following a circuit interruption the circuit interrupter may be reclosed by merely pushing upwardly on indicator 53 until roller 58 again engages projection i0. Preferably such reclosing operation is performed While the door 34 and associated circuit interrupter 35 are removed from housing l5. When the contacts 43 and 48 are reclosed the door or cover may be replaced and moved to the closed position in the same manner as the doors or covers of the enclosed fuse'cutouts of the prior art. With my arrangement, however, no replacement of a burned out fusible element is required.

The operation of the fuseless cutout of my invention will be obvious from the detailed description included above and, as will be obvious from this description, the present invention provides pronounced advantages over fuse cutouts of the prior art in that it is unnecessary to replace any parts before the circuit may again be complated after circuit interruption, it being merely necessary for the lineman to reclose the circuit interrupter in the manner described above. Also an indication of the condition ofV thefuseless cutout is at all times evident to the lineman.

Some times it is desirable in enclosed cutout devices to open the door or cover following a ciri copending application, Serial No. 459,791, led

September 26,' 1942, now Patent 2,357,853, and assigned to the same "assignee as the present application, I f

Although I have disclosed the current or thermal-responsive means of my invention as a bimetallic element 56, it will be obvious that other current .or thermal -responsivemeans might equally well be employed, such forexample as are disclosed in the copendin'g application of George F. Lincka'Serial No. 522,584, filed February 16, 1944, and assigned to the samefassignee as the present application or in Figs. 5, 6 and '1 of the drawings of the present application'. Also in accordance with the above mentioned Lincks application, my fuseless cutout maybe of the automatic reclosing type if desired.

InvFigs. 5, 6 and '1 of the drawings, I havedisclosed a modliication of the vacuum type i useless cutoutof my invention. Since the housing for the fuseless cutout shown in Figs. 5, 6 and '1 would be substantially identical with the housing'of Fig. 2, it has been omitted for the sake of simplicity in the drawings. As in the fuseless cutout of Fig. 2, a. door or cover 66 is provided, having a manually engageable handle G1. A U-shaped hinge support 68 is fastened to the lower inside face of door 56 by means of screws'89. This U- shaped hinge support is provided with a hookshaped portion 10 similar to the hook-shaped portion 38 of Fig. l which is engageable with ,the hinge pin 39. A suitable support H is bolted to the inside face of door 56 near the upper end thereof for supporting in any suitable manner the stationary contact 12 of thecircuit interrupter 13 mounted on door 66. `A vterminal cap 14 electrically connected to stationary contact 12 is provided so as to be engageable by the contact nger'22 and spring clip 24l of upper `contact assembly l1.

Stationary contact 12 extends into an evacuated envelope -15 preferably constructed4 of suitable insulating material, such as glass or the like. A suitable seal between stationary contact 12 and evacuated envelope 15 ls provided. Movably mounted in evacuated envelope 15 is movable contact 18 which is attached to a tubular switch arm 11. This switch arm 11 extends through and preferably is brazed or otherwise suitably sealed to a diaphragm 18 which is suitably sealed to the lower end of evacuated envelope 15. When the vacuum switch comprising envelope 15 and contacts 12 and 16 is assembled, it is evacuated to a high degree of vacuum through tubular switch arm 11 after which the tubular switch arm is flattened and sealed exteriorly of the casing or envelope 15 as indicated at 19. The lower end of evacuated envelope 15 is additionally supported from door 85 by means of a spring clip 80 suitably fastened to door 55 as indicated at 8| in Fig. 5.

In order to bias relatively separable contacts ofinsulating material 82 which is disposed so that the end of switch armv 11 extends'into the upper end of the bore in tube 82. A suitable washer 83 on the upper end of tube l2 engages with the emerged flattened portion 15 of switch

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