US1970392A

US1970392A - Electric circuit breaker

Info

Publication number: US1970392A
Application number: US544306A
Authority: US
Inventors: William E Paul
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1931-06-15
Filing date: 1931-06-15
Publication date: 1934-08-14
Anticipated expiration: 1951-08-14
Also published as: GB389691A

Description

Aug. 14, 1934.

w. E. PAUL. 1,97%392 ELECTRIC CIRCUIT BREAKER Filed Jun 15, 1931 lnvantov z William Elpaaul, y

H i5 Attmrney.

Patented Aug. 14, 1934 UNITED STATES PATENT OFFICE General Electric Company,

York

Application June 15, 1931,

6 Claims.

My invention relates to electric circuit breakers, more particularly to circuit breaker tripping mechanism for effecting circuit opening movement at high speed immediately in response to the tripping impulse.

In the operation of modern high tension transmission systems comprising a network of high tension lines interconnecting a number of generating stations, it is often necessary to clear a circuit upon the occurrence of a short circuit or other fault within a few cycles in order to maintain system stability. The conventional oil circuit breakers generally used for this purpose receive a tripping impulse through a trip coil, the trip coil in turn actuating a latch or release causing switch opening movement. Since the movin parts of the breaker, including the usual linkage mechanism, operating rod and bridging member, are of considerable mass, acceleration of the movable structure involves a certain time lag after the release. This, together with the time required for the coil to release the mechanism, comprises the time between the tripping impulse and the separation of the switch contacts and may take up a number of cycles endangering system stability unless the circuit is interrupted within a cycle or so of arcing.

It is a principal object of my invention to provide an improved high speed circuit breaker wherein the tripping mechanism acts directly on a movable switch member of comparatively small massfor opening the circuit immediately in response to the tripping impulse.

In accordance with my invention the movable switch member of the circuit breaker is operatively related to an operating rod through a connection allowing relative movement between the same, the said switch member comprising the current-carrying element of electromagnetic tripping means for releasing said switch member with respect to said rod For insuring rapid opening movement of the switch member independently of the operating rod immediately upon actuation of the electromagnetic tripping means energy storing means, as compression springs, are provided. By reason of the small mass of the switch member as compared with the operating rodand associated mechanism acceleration of the sameby the energy storing means is very rapid.

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 withparticularity in, the claims annexed to and forming a part of this specification,

a corporation of New Serial No. 544,306

Referring to the drawing, Fig. 1 illustrates an elevational view, partly in section, of the contact structure of a circuit breaker embodying my invention, and Fig. 2 is a sectional detailed view of the tripping mechanism.

As illustrated in the drawing my invention is shown applied to a fluid break or oil circuit breaker of a well-known type wherein a pair of contact structures immersed in oil are interconnected by a conducting bridging member to complete the circuit. It shall be understood, however, that my invention is readily applicable to circuit breakers of other types wherein immediate and high speed opening movement is desired.

The circuit breaker in the present instance comprises a movable switch member, as the bridging member 1 formed of spaced conducting bars, relatively movable with respect to the operating or lift rod 2, and interconnecting a pair of stationary contact structures, as explosion chamber pots 3 and 4 of a well-known type. The explosion chamber pots are supported at the lower ends of the insulating bushings 5 and 6 which are mounted in the cover of the circuit breaker tank (not shown) and through which the lead-in conductors '7 and 8 extend. In the closed circuit position illustrated in Fig. 1 the circuit between the lead-in conductors I and 8 is established by the bridging member 1 and attached rod contacts 9 and 10 which extend within the explosion chambers and engage the corresponding stationary contacts which are electrically connected to the corresponding lead-in conductors. In the conventional circuit breaker of this type the operating rod 2 is rigidly connected to the bridging member 1, and the tripping mechanism is associatedwith levers and toggle links operatively connected to the rod 2 so that when the tripping impulse occurs the mass of the entire structure must be accelerated in effecting separation of the switch contacts.

For the purpose of permitting switch opening movement of the bridging member 1 independent- 1y of the operating rod 2 there is provided tripping mechanism comprising the latches ll pivotally mounted as at 12 between a pair of plates 13 suitably secured to the operating rod 2. The plates 13 are spaced as illustrated in Fig. 2 and form guiding means within which the bridging member 1 may move vertically between upper and lower limits. The bridging member is held in the upper closed circuit position illustrated against the bias of compression springs 14 by the latches 11 so that the bridging member and rod are locked together as a unit. The springs 14 seat at one end on the stationary lugs 15 secured to the rod 2 and at the opposite end on a pair of members 16 secured as at 17 to the bridging member 1. Each member 16 is provided with a lug 18 coacting with a roller 19 carried by one arm of the corresponding latch 11, each latch being biased in a clockwise or latching position as by a spring 20. With the bridging member 1 latched in position as illustrated, the springs 14 are under compression and upon release of the members 16 by the latches 11 the bridging memher 1 is Immediately urged in a downward or circuit opening direction independently of the rod 2.

The tripping impulse inthe present instance, causing actuation of thelatches 1,1, is derived from a pair of U-shaped electromagnets 21 which are secured to the plates 13 and straddle the bridging member 1 so as to be energized bycur-- rent flowing through the switch. Opposite the upper open end of each magnet 21 is a bar shaped armature 22 forming an extension of latch 11. Accordingly, energization of theelectromag: nets 21 by current through the bridging member suificient to attractl the coacting armature 22 serves to trip the breaker and cause opening movement gof the bridging member 1 by the compression springs l4. The connection allowing relative movement betweenthe rod 2 and bridg ing,member 1 is preferably so designed that the circuit, is normally cleared by the travel of the bridgingmember alone. g

,It .will therefore benoted that only theessentiaLcuIIent-carrying parts of the switch move during the circuit interrupting. operation, it being understood of course that the operating rod 2 maydllgewise be operated in the usual manner to increasethe distanceof'separation between the contacts. Such an arrangement is moreover preferred since the energy stored in the moving opcrating. rod may be used to reset the latching mechanism so that theswitch is in readiness for a subsequent closing operation. To this end there arel rovidedla pair of buffers 23, each comprising a; compressionspring 24 and acap 25 slidable on asstop member 26, the buffers being disposed on astationary part of the circuit breaker substantially below the opposite ends of the bridging member 1; In,the dotted line position of'the movable contact structure the bridging member 1 has moyed to its lower limit with respect to the operating rod; 2 WhiCh has now likewise descendedWWhen the bridging member 1 strikes the buiiers 23 it is stopped without: shock whereas the inertia. ofthe operating rod 2 causes it to continue its downward movement with the result that the springs 14 are again compressed and the latches 11 are cammed over the corresponding lugs 18 and snap into the latching position as shpwnin the full linefigure. The circuit breaker is,th ereore immediately in readiness fora reclosing operation and in case the short circuit or other fault; still persists the breaker is again imm diatelytripped free of the operating rod.

which the breaker "is trippedi 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 spirit of my invention.

What I claim as new and desire to secure by Letters Patent of the United States, is:

1. An electric circuit breaker comprising a pair of stationary contact structures and a movable conducting bridging member connecting said structures in the closed circuit position, an operating rod relatively movable with respect to said bridging member, springs biasing said bridging member towards open circuit position independently of said rod, and electromagnetic tripping means including said bridging member and a latch pivotally mounted member at high speed. l

2. In an electric circuit breaker comprising relativelymovablecontacts including a conductto member.

member, a latch locking said bridging member to said rod as a unit, a spring biasing said bridging member towards open circuit position independently of said rod in response to actuation of said latch, and means limiting the circuit opening movement of said bridging member so that the inertia of said operating rod is efiective to cause resetting of said latch.

6. Circuit interrupting apparatus comprising stationary contact structure and a movable bridging member coacting therewith, an operating rod relatively movable with respect to said bridging member and forming guiding means therefor, a latch locking said bridging member to said rod as a unit, a spring biasing said bridging member towards open circuit position in response to release of said latch, electromagnetic means energized by current through said bridging member for actuating said latch and causing opening movement of said bridging member, the travel of said bridging member with respect to said rod being sufiicient normally to clear the circuit, and means other than said rod limiting the opening movement of said bridging member causing resetting of said latch and compression of said spring by the inertia of said rod.

WILLIAM E. PAUL.