Electric circuit breaker

Oct 23, 1934.

K. BAUERSCHMIDT

ELECTRIC CIRCUIT BREAKER Filed Jan. 26, 1934

1,978,246

<img file="US1978246A_D0001.tif" />

<img file="US1978246A_D0002.tif" />

<img file="US1978246A_D0003.tif" />

<img file="US1978246A_D0004.tif" />

Inventor: Ku.no Sauer schmidt, by £. His Attorneu.

Patented Oct. 23, 1934

1,978,24«

UNITED STATES PATENT OFFICE

1,978,246

ELECTRIC CIRCUIT BREAKER

Kuno Bauerschmidt, Berlin-Karlshorst, Germany, assignor to General Electric Company, a corporation of New York

Application January 26, 1934, Serial No. 708,447 '

In Germany March 31,1933

Claims. (CL 200—166)

My invention relates to electrite circuit breakers, more particularly to liquid-break or oil circuit breakers of the well known finger-contact type wherein a movable contact member or bridging 5 conductor is engaged or clasped at opposite sides thereof by coacting finger contact members, and has for its principal object the provision of improved circuit breaker contact structure of the aforesaid type.

My invention will be more fully set forth in the following description referring to the accompanying drawing, and the features of novelty which characterize my invention will be pointed out with particularity in the claims annexed to and 15 forming a part of this specification.

Referring more particularly to the drawing, Fig. 1 is an elevational end view, taken along the line 1—1 of Fig. 2, of circuit breaker contact structure embodying the present invention and 20 Fig. 2 is a side view of the aforesaid contact structure.

Fig. 1 illustrates relatively movable contact structure of one pole of a liquid-break circuit breaker comprising a so-called fixed contact 25 structure 1 and a movable contact member 2, the contact structure being in open circuit position. The fixed contact structure includes a plurality of pairs of coacting contact members 3 and 4, known generally as finger contacts, ar30 ranged to engage the opposite sides of the movable contact or blade 2 when the same is elevated to the closed circuit position. The aforesaid contact structure is immersed in a suitable insulating liquid as oil.

The contact members 3 and 4 each comprise a conducting strip rectangular in cross section and pivotally supported at 5 and 6, respectively, so that there is a certain degree of lost motion or play between a contact member and its pivot 40 pin as clearly illustrated by Fig. 1. The ends of the contact members 3 and 4 adjacent the loose pivotal mountings thereof are shaped as at 3’ and 4', respectively, to have a combined rolling and sliding contact engagement with coacting 45 contact surfaces formed by a conducting member 7 which is in turn connected to the lead-in conductor stud 8. Such direct contact engagement is made possible by the play at the pivots 5 and 6.

Referring more particularly to Fig. 2, the con50 ducting member 7 comprises a contact supporting block at the opposite ends of which depend plates 9 and 10 in which the pivot pins for the contact members are mounted. As illustrated in Figs. 1 and 2, a plurality of contact members 55 3 and 4 are spaced with respect to each other as by spacing washers 6' and mounted on the respective transversely extending pivot pins so that the movable bridging member 2 is engaged at each side thereof by a plurality of contacts.

For the purpose of biasing the finger contact 60 members towards each other and into contact engagement with the bridging member in the closed circuit position, resilient means as springs 11 and 12 are positioned under initial tension between the finger contacts 3 and 4 and the re- 65 spective ends 11' and 12' of a rod member 13 which extends adjacent and between the finger contacts as illustrated by Fig. 2. Each rod 13 is provided with bearing plates 13' slidably mounted thereon and arranged to engage two 70 pairs of coacting contact fingers. A bar 14 is supported between the lower ends of the plates 9 and 10 and forms a positioning and stop member for the finger contacts as illustrated by Fig. 1.

When the movable contact blade 2 is elevated 75 to close the circuit the finger contacts 3 and 4 are engaged and wedged apart by the movable contact, the tensioned springs 11,12 serving to establish uniform contact engagement between the coacting surfaces of the contacts. The springs 11 80 and 12 therefore not only serve to equalize the contact pressure at opposite sides of the movable contact and to compensate for a limited degree of mis-alinement between the center lines of the fixed and movable contact structures but also 85 to press the ends 3' and 4' of the finger contacts directly into engagement with the conducting member 7. By reason of this direct contact engagement between the finger contacts and the stationary conductor stud, the current may be 90 carried through the stationary contact structure without the provision of the usual flexible conductors interconnecting these elements and without relying on the pivotal support which is considered an unsatisfactory electrical connection. 95 Furthermore, the combined rolling and wiping action of the contact portions 3' and 4' at the coacting contact surfaces serves to maintain good electrical contact. It will be apparent that the desired contact pressure may readily be obtained 100 by adjusting the tension of the springs 11 and 12 and also by varying the distance of the application of spring pressure from the pivot points.

In addition to compensating for a limited degree of horizontal mis-alinement of the contacts, 105 the contact arrangement likewise provides for a limited degree of angular mis-alinement of the bridging member. In the event of such misalinement the coacting pairs of finger contacts engage with equal contact pressure the opposite 110

1,978,246 sides of the bridging member even though the finger contacts of adjacent pairs are out of alinement. In other words the finger contacts of each group make equalized contact engagement with 5 the corresponding portion of the bridging member regardless of the position of the other contact fingers.

It will be apparent that the biasing means including the rod 13 which is common to oppositely 10 disposed finger contacts may be related, if desired, to a single pair of finger contacts or to a plurality of pairs, depending on the current-carrying and other requirements of the circuit breakers.

It should be understood that my invention is not limited to specific details of construction and arrangement thereof herein illustrated, and that changes and modifications may occur to one skilled in the art without departing from the 20 spirit of my invention.