US2291357A - Electric circuit breaker - Google Patents

Description

July 28, 1942. H. E. STRANG ELECTRIC CIRCUIT BREAKER Filed June 8, 1940 2 She etS-Sheet 2 Inventor: Harold E.5tT-ang,

'His Attor'hey.

Patented July 1942."

ELECTRIC BREAKER Harold E. Strung, Arilmore, Pia, assignmto General Electric Company,

York

a corporation of New Application June s, 1940, Serial No. 339,523

7 Claims.

My invention relates to electric circuit breakers and more particularly to operating mechanisms for high-speed circuit breakers.

In the operation of modern high-tension transmission systems comprising a network of hightension 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 moving parts of-thetcircuit breaker including the usual linkage mechanism, operating rod, and

bridging. member are of considerable mass, acceleration of the movable structure involves a lit certain time lag after 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 arid may take up quite a number of cycles, endangering system stability unless the circuit is interrupted within a cycle or so of arcing. It-would be desirable to provide a highspeed circuit breaker wherein the circuit is in-- terrupted within a minimum or time without endangering the system stability.

It is an object of my invention to provide an improved high-speed circuit breaker wherein the mass or the operating mechanism for the circuitinterrupting contacts is reduced to a minimum so that high-speed circuit interruption may be ob-' tained.

It is another object of my invention to provide a circuit breaker having separate arcing and isolating contacts including separate operating interruption may be obtained.

Further objects and advantages of my invention will become apparent as the following de= scription proceeds and the features of novelty which characterize 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 cross-sectional view of the circuit breaker embodying my invention, and Figs. 2, 3, 4 and 5 are cross-sectional views through the upper portions of circuit breakers embodying my invention to illustrate various modifications oi the arrangement of Fig. 1.

It will be understood by those skilled in the mechanisms therefor so that high-speed circuit art that my invention is of general application but. for purposes of illustration, I have shown my invention as applied to oil circuit breakers having a separate breaker for each phase oi'the circuit to be interrupted.

Referring now to Fig. 1, the housing or pressure confining casing enclosing the switch contacts and the insulating liquid in which they are immersed comprises essentially the metal cylinder ill, the bottom end head M, and the top cover iii, the entire casing being constructed to withstand relatively high pressures. Thebottom end head it and the cover iii comprise domeshaped members, preferably pressed out from sheet-metal stock. The bottom end head it has its flangededge fitted withinand welded to the cylinder it], thereby forming the tank.

A pair of insulator bushings l3 and i3, only portions of which are shown, are supported by the cover it? through which they extend in the well known manner so as to be connected with an external electric circuit. Insulator bushings i3 and i3 are provided at the lower end thereoi' with fixed isolating contacts l5 and I5 respectively each comprising a plurality of resilient fingers and are adapted to be bridged by a movable bridging contact member l6 which is actuated by the operating or lift rod ll extending up to the operating mechanism above. The arrangement thus far described is substantially the same as that'of the electric circuit breaker described and claimed in United States Letters Patent No. 1,816,799 to J. W. Opp and William K. Rankin, granted July 28, 1931, and assigned to the same asslgnee as the present application.

The operating mechanism for producing relativemovement between isolating contacts I5 and I5 and bridging member 86 by imparting vertical movement to operating rod i1 connected to the latter is housed for themost part in an upward extension is of cover l2, a rectangular opening being cut away in the central portion of the head comprising the cover it. The operating mechanism for imparting straight-line vertical motion to operating rod ii is substantially the arrangement disclosed and claimed in United States Letters Patent 1,75%,179 to William K. Rankin, granted April 8, i930, and assigned to the same assignee as the present invention. This fill intermediate portion of link 22 is pivotally conl and ll. To eliminate any reversal of this order, I provide an interlock 65 connected to arcing contact actuating rod 62 which will pre-= vent arcing contact actuating rod 62 from closing the contacts of arcing contact structures 69 and 30' prior to the engagement of contacts l and IS with bridging member l6 and which will not allow bridging member. IE to be disengaged from isolating contacts l5 and it prior to the interruption of the circuit by the arcing contacts associated with arcing contact structures 60 and 40. A spring 66 is provided with inter lock 65 to eliminate impact between the two operating systems.

The. arrangement just described permits very eificient high-speed circuitinterruption wherein the operation of the long stroke and relatively low-pressure isolating contacts is taken care at by one operating mechanism while a second oper atlng mechanism handles the short strains and relatively heavy pressure arcing contacts. lit will be understood by those skilled in the art that this arrangement is readily adaptable for higinspebd reclosing circuit breakers and a control system may be provided, causing operation of the arcing contacts to interrupt the circuit without relative movement of the isolating contacts having taken place. The arcing contacts are immediately reclosed and, if the fault has cleared, the isolating contacts are not operated. If the fault cannot be cleared, as may be indicated by-several successive opening and reolosing operations of the arcing contacts, then the isolating contacts may also be operated.

The operation of my high-speed circuit breaker illustrated in Fig, 1 will be understood by those skilled in the art. Upon the occurrence of an abnormal current condition on the circuit with which my invention is associated, a tripping im= pulse will be transmitted to the operating mechanism contained within housing 35, causing movement of rod 64 thereby producing relative movement of tlie arcing contacts to interrupt the circuit. This circuit interruption may take place at very high speeds since a relatively small movement of the operating mechanism is required and it is unnecessary to wait for the operation of bridging member I6 associated with the relatively heavy operating mechanism which, must produce considerable movement thereof as in prior art devices in order to interrupt the circuit. lnter= lock 65 will prevent bridging member it from disengaging with contacts is and it until the arcing contacts within chambers 3i and ti have interrupted the circuit. When reclosing the contacts, interlock 65 will require that isolating contacts l5 and i5 are bridged prior to the closure of the arcing contacts, and, if an abhor-=- mal current condition should occur during the closing operation of the circuit breaker, the trip free mechanisms, not shown, contained within housing 35 will allow immediate reopening of the circuit.

In order to increase the opening speed of the circuit breaker,'I have shown an arrangement in Fig. 2 wherein the mass of the operating parts associated with the arcing contacts is decreased and, furthermore, wherein a single phase of the polyphase system may be interrupted without affecting the other phases. The parts of Fig.2 similar to Fig.1 are designated by the same reference numerals. The operating mechanism for the isolating contacts is identical with that oi Fig. 1. However, while the linkage connected to rod 34 causes both the opening and closing of the isolating contacts, the operating mechanism associated with rod 64 does only the closing of the arcing contacts and takes care of trip-free protection in a conventional manner while the nor- 5 mal tripping oi the arcing contacts takes place within each tank to. The operating mechanism associated with red ti l is shown solid in the position at the end of the closing stroke of the circuit breaker after which the operating mechalit 'nism associated with rod M is deenergized and is returned to the dotted position of certain parts shown in Fig. 2. in order to close the arcing contacts associated with lift rods 53 and t3, link 88 is connected to a lever 88 pivotally mounted lit at 69 and arranged to be rotated in a clockwise direction by lever it having one end thereof pivoted at 69 while the other end is connected to arcing contact actuating rod 62 at "it. lever to is provided with an extension it including a pin as; it which engages with the end of lever 68 remote from link 58 to cause clockwise rotation thereof and closure of the arcing contacts when operating rod 6t m moved downwardly to the solid position shown in Fig. 2. The end of lever 68 is as provided with a roller id arranged to be engaged by pivotallymounted latch it, which normally tends to assume the vertical position, but which may be provided with spring means, not shown, .ESD as to be biased toward the latching position to hold the arcing contacts in the closed-circuit pofsition even when interlock 65 and lever 10 assumethe dotted positions shown in Fig. 2. In

case of an abnormal current condition, trip coil I6 is energized to cause counterclockwise rotation of latch I5, thereby releasing lever 68 and allowing downward movement of lift rods 53 and 53' under the influence of springs 56 and 56' of Fig. l to cause interruption of the circuit at the arcing contacts. In case operating rod 35 is it moved either manually or by accident, I. provide a hook T! associated with isolating contact actuating rod 32 which engages with cooperating member l8 associated with latch E5 to cause tripping of the arcing contacts. Since interlock g has been moved away from its interference position (see dotted position of Fig. 2) as soon as the operating mechanism for rod $4 is deenergized hook 'i'l is now necessary to insure circuit interruption at the arcing contacts.

In order to operate the circuit breaker of Fig. 2 as a reclosing circuit breaker, a suitable switch it associated with linlr 58 may be provided to initiate rec'losing oi the arcing contacts as soon as they are opened. Suitable switches 6t and 8t may also be provided to act as cut-0d switches or to control signalling means as will be well understood by those skilled in the art. It will he observed that, by virtueof hook ll associated with isolating contact actuating rod 32, opening movement of rod 36 will cause tripping of the arcing contacts of all the breakers associated with actuating rod 32. It will also be observed that, with the arrangement of Fig. 2, any phase may be interrupted and the circuit reclosecl with- 5 out disturbing the other phases. As will be understood, any conventional control circuit may be provided.

In order to increase the speed of operation when trip-free operation is desired, I hav shown an arrangement in Fig. 3 wherein rod E i is moved only to close the arcing contacts and the mass or? this rod and associated mechanism need not be moved during trip-free operation. To accomplish this, I provide a trip-freeiinltage, with 75. bothcthe trip-free latch and prop, in the upper eration of the arrangement disclosed in Fig. 3-

willbeobvioustothoseskilledintheart.

In thearrangement disclosed in Fig. 4, I haveentirely eliminated the mechanical operating means for lift rods It and 58', whereby each phase of the polyphase circuit breakers may be individually controlled for circuit closing as well as for circuit interruption. In this arrangement, separate trip-free opening and closing units generally indicated at l! are provided for each phase. The corresponding parts of Fig. 4 are designated by the same reference numerals as in the prior disclosures and the trip-free linkage "is verysimilartothatofl'ig.3.except thata closing solenoid 84 has been provided to close the arcing contacts instead of the flexible member included in mechanism 02 of Fig 3 attached to arcing contact actuating rod II. It will be understood that, with the arrangement of Fig. 4,

- the masses of theRclosing as well as of the tripping parts have been reduced to a minimum with consequent increase in the speed of operation particularly when used as a reclosing circuit breaker.

.- In Fig. 5, I have disclosed an operating mecha- I nism substantially the same as that of Fig. 4 except that a self-latching solenoid mechan sm enerally indicated at ll of the type disclosed and broadly claimed in copending application Serial No. 248,783,. filed December 30, 1938, on behalf of Eugene W. Boehns, and assigned to the same assigneeas the present application, now Patent No. 2,278,971, dated April 7, 1942, is employed. This arrangement simplifies the construction to a considerable extent and, due to the magnetic latch, will give considerably faster tripping. It will be understood that, in the arrangement of Fig. 5, electrical interlocking will be provided to obtain the proper sequence of operation between the isolating and arcing contacts.

While I have shown and described several particular embodiments of my invention as applied to electric circuit breakers, it will be obvious to those skilled in the art that various changes and modifications may be made without departing contacts and an isolating contact connected in series with one another and mounted in said housing, an arc-confining chamber within which said arcing contacts are mounted, an are-quenching liquid within said casing. said casing having exhaust ports adjacent and opposite a break formed by separation of said arcing contacts so that are pressure created within said casing upon opening of the circuit is effective to drive liquid through the are at said ports, said isolating contact being located extericrly of said casing. an operating mechanism for said arcing contacts. and a separate operating mechanism for said isolating contact so that high-speed interruption of said circuit may be obtained.

2. In an electric circuit breaker comprising a .plurality of relatively movable arc-extinguishing contacts and an isolating contact connected in series with one another, an arc-confining chamber within which said arcing contacts are mounted, an arc-quenching liquid within said casing, said casing having exhaust posts adjacent and opposite a break formed by separation of said arcing contacts so that are pressure created within said casing upon opening of the circuit is eii'ective to drive liquid through the are at said ports, said isolating contact being located exteriorly of said casing, an operating mechanism 'for said arcing contacts, a separate operating mechanism for said isolating contact so that high-speed interruption of said circuit may be obtained, and interlocking means for requiring operation of said isolating contact prior to the closure of said arcing contacts while permitting said isolating contact to perform its function only after the opening of said arcing contacts.

3. In a multiphase electric circuit interrupter. a plurality of relatively movable arcing contacts for each phase to be interrupted, a flurality of relatively movable isolating contacts connected in series with said arcing contacts, operating means for producing simultaneous relative movement between the isolating contacts associated, with all of said phases, and'a plurality of separate operating means one associated with the arcing contacts of each phase so that high-speed circuit interruption may be obtained.

4. In a multiphase electric circuit interrupter. a plurality of relatively movable arcing contacts for each phase to be interrupted, a plurality of relatively movable isolating contacts connected in series with said arcing contacts, operating means for producing simultaneous relative movement between the isolating contiicts associated with all of said phases, a plurality of separate operating means one associated with the arcing contacts of each phase so that high-speed circuit interruption may be obtained, and interlocking means for causing operation of all of said separate operating means associated with said areing contacts in the event that relative separation between said isolating contacts occurs.

5. In anelectric circuit interrupter, a housing, a pressure-confining chamber mounted in said housing, a plurality of relatively movable arcing contacts mounted in said chamber, a plurality of relatively movable isolating contacts connected in series with said arcing contacts and mounted in said housing, operating means for producing relative movement of said isolating contacts, and separate operating means having a much lower inertia than said first-mentioned operating "means for producing relative movement of said arcing contacts to insure high-speed circuit interruption.

6. In an electric circuit interrupter, a housing,

a pressure-confining chamber mounted in said housing, a plurality of relatively movable arcing contacts mounted in said chamber, a plurality of relatively movable isolating contacts connected in series with said arcing contacts, operating means for producing relative movement of said isolating contacts, separate operating means having a much lower inertia than said first-mentioned operating means for producing relative movement of said arcing contacts to insure highspeed circuit interruption, and interlocking means for requiring closure of said isolating contacts prior to the closure of said arcing contacts while permitting said isolating contacts to open only after the opening of said arcing contacts.

7. In an electric circuit breaker, a housing, a pressure-confining chamber mounted in said housing, a pair of relatively movable arcing contacts mounted in said chamber, a pair of relatively movable isolating contacts connected in series with said arcing contacts and mounted in said housing, said arcing contacts being arranged July'28, 1942. H. -w. UHLRIG ETAL COOKING DEVICE Origigal Filed Jan. 26, 1939 2" Sheets-Sheet 1 s m w r Jw Wm m jw ww w rd a Ha N

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