US2230735A - Pneumatic reclosing mechanism for circuit breakers - Google Patents

Description

Feb. 4, 1941. H. VERSE 2,230,735

PNEUMATIC RECLOSING MECHANISM FOR CIRCUIT BREAKERS Filed Nov. 7, 1938 2 Sheets-Sheet l plg.l- 9 V] r 5-f-1\ 6/ V v ,/Z M f r X Fig. la. /7

His Attorney.

Feb. 4, 1941. H. VERSE 2,230,735

PNEUMATIC 'RECLOSING MECHANISM FOR CIRCUIT BREAKERS Filed Nov. 7, 1938 2 Sheets-Sheet 2 F" 1g. 2. w I ll 9 7 f I A H ahshe'mrich Verse,

His Attorney.

Patented Feb. 4, 1941 UNITED STATES PNEUMATIC RECLOSIN G MECI'IANISBI FOR CIRCUIT BREAKERS Hansheinrich Verse, Braunschweig, Germany, assignor to General Electric Company, a corporation of New York Application November 7, 1938, Serial No. 239,353 In Germany December 23,1937

3 Claims.

My invention relates to high speed reclosing mechanisms for circuit breakers, and more particularly to those of the pneumatic type having application, for example, to gas blast circuit breakers.

Electric circuit breakers are often required which permit of very rapid reversal of the switch movement, as, for example, where it is desired immediately to reclose the circuit breaker after the interruption of a short circuit. In circuit breakers of this character, it is, therefore, highly desirable that the factors tending to retard the speed of the reclosing movement, such as back pressure, mass of the reciprocating parts, etc, be eliminated or reduced in so far as is possible.

In the case of gas blast circuit breakers wherein pneumatic operating means is often employed because of the available pressure source, the reclosing mechanisms heretofore available are inherently slow as to reclosing. As commonly used, a single three-way cook or valve is in communication through fiuid conduits with opposite ends of the piston cylinder for both applying pressure to the piston and venting the cylinder. This arrangement necessarily involves a considerable amount of resistance or back pressure when the residual gas in the piston cylinder is being discharged during the reversal or reclosing mo -.1- ment. Furthermore the back pressure in this design can be reduced only to a limited extent, since the pressure connections between the cylinder and valve are necessarily of appreciable length and the valve passages are, of course. restricted in cross section due to practical considerations in' the valve design.

In accordance with my invention, rapid reversal of the switching movement is obtained by means of one or more valves, such for example as slide valves, that are operatively related to the switch operating pneumatic motor, such cylinder and piston. so as directly to con ol the exhaust ports. The valve controlled ports can be of comparatively large cross section and can exhaust directly to atmosphere so that no appreciable back pressure can exist. With this arrangement the residual gas in the piston cylinder can be displaced rapidly with negligible retarding effect during the switch reversing movement.

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

Referring to the drawings, Fig. 1 is an elevational view, partly in section and partly diagrammatically shown, of a pneumatic reclosing 5 mechanism embodying the present invention; Fig. 1a. is a detail viewof structure shown in Fig.

1; Fig. 2 is a view similar to Fig. 1 showing another form my invention may assume, and Fig. 3

is an elevational sectional view of a further modification of my invention.

The mechanism shown by Fig. 1 comprises essentially a pneumatic operating device or motor 1, an electric circuit breaker 2 actuated thereby, and fluid pressure controlling valves VI and V2 for applying fluid pressure to the motor. The circuit breaker per so which may be of any suitable type, such as gas blast, oil, etc., forms no part of the present invention aside from its cooperation with and relationship to the motor I and is shown in simplest form wherein a reciprocally guided rod contact 3 coacts with a fixed socket contact 4.

Referring more particularly to the pneumatic device I, a fixed cylinder 5 is provided with a piston 6 that is directly connected through the piston rod 1 and a pivoted lever 8 to the circuit breaker, so as to cause circuit opening and closing movement of the breaker in response to reciprocal movement of the piston. The cylin- 3o der 5 is adapted to be in communication with a source of pressure at its opposite ends through the valve controlled conduits 9 and Ill.

The cylinder 5 is provided at its opposite ends with exhaust ports H and I2, respectively, for 3 venting the gas at the low pressure side of the piston during a working stroke. For the purpose of controlling these exhaust ports in accordance with the position and operation of the piston 6, valve means coact directly with the cylinder exhausts and the piston for opening the exhaust ports at the end of the cylinder opposite the piston substantially at the completion of a circuit controlling stroke. Accordingly, the motor is in immediate readiness for a quick return stroke of the piston.

As shown in a specific form by Fig. 1, the valve means comprises a slide valve l3 of the sleeve type concentrically mounted on the fixed cylinder for reciprocal movement thereon. The valve I3 is also provided with exhaust passages H and I2 for coacting respectively with the cylinder exhaust ports II and I2. These exhaust ports and corresponding valve passages can, if desired, be spaced circumferentially at opposite 55 ends of the cylinder so that the total or effective exhaust passage area is quite large. Accordingly, in view of the fact that the exhaust path to atmosphere through the valve passages is of negligible length, there is eliminated the possibility of appreciable back pressure at the low pressure side of the piston.

For the purpose of relating the valve l3 to the piston and circuit breaker in the manner above described, a lost motion connection, such as a pin and slot arrangement between the valve and the piston rod 1, can readily be employed. A pin or bar l4 fixed at l5 to the piston rod is operable within slots in a pair of depending valve extension members l6. Fig. 1a is a detail view of one of the extension members which are suitably secured to the overhanging flange B of the valve. The pin 14 during the greater part of a working stroke is free to slide in the slots l'l until a predetermined point indicated by the dotted line positions of the piston and pin is reached. The pin then engages the members- It at the lower part of the slots to move the valve l3 so as to uncover one set of ports and close the other set. The reverse operation takes place on the return stroke.

Referring more particularly to the operation, and assuming that the device is in the open circuit position shown in Fig. l, the circuit breaker closing operation is initiated by opening the closing valve VI in any suitable manner, as by a remote controlled operating solenoid l8. Gas under pressure is then admitted to the upper closed end of the cylinder 5 and the piston 6 is moved to the lower dotted line position to close the circuit breaker 2. Substantially at the completion of the circuit closing stroke, the lost motion connection above described causes downward movement of the sleeve valve [3 so as to close the exhaust for the valves VI and V2 can be suitably interlocked by methods well known in the art, such control means per se forming no specific part of the present invention. In practice the valve VI would be open for a brief interval so as to be closed when the piston 6 reaches the lower position indicated. Even in the event that the valve VI is somewhat late in closing, the large exhaust area at the ports I I would prevent the building up of appreciable back pressure within the cylinder.

It will be noted that when the reclosing operation -is initiated by the valve V2, the reciprocating mass to be accelerated does not include the valve 3, and in fact only the essential elements comprising the piston and movable contact structure need be accelerated throughout substantially the entire reclosing stroke. The operation of the valve at the end of the stroke does not retard the reclosing stroke by reason of the high speed of the moving parts at this point. Therefore, the pneumatic reclosing device embodying my invention has inherently high speed reclosing characteristics since the mass of the reciprocating parts is reduced to the essential elements and the back pressure at the low pressure side of the piston is practically eliminated.

The arrangement shown in Fig. 2 is essentially the same except that a fiat slide valve 20 instead of a sleeve valve is used for controlling the exhaust ports II and I2 of the cylinder 5. The slide valve 20 is guided and resiliently biased into seating engagement with the cylinder 5 by means of a spring 2| secured to an overhanging flange 22 of the fixed cylinder structure. The pin and slot connection at M and I6 is substantially the same as that previously described, as is the arrangement of the operating valve VI and V2.

For the purpose of indicating the valve and circuit break-er positions, a simple signal switch 23 can be connected to the valve member l6 so as to operate signal means, such as lamps indicated at R and G. i

Fig. 3 illustrates another form wherein the piston 5 is provided with individual slide valves 24 and 25 operated through the piston rod 1. The piston rod 1 is connected through a lever 26 and link 21 to individual cranks 28 and 29 for operating the slide valves 24 and 25, respectively, generally in the manner above described. The link 21, which is suitably guided for vertical movement, is provided with spaced stops 30 for operating the cranks 28 and 29 in the manner desired. As in the previous cases, the valves 24 and 25 function to open the cylinder at the low pressure end immediately prior to the reclosing stroke and vice versa.

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. Pneumatic reclosing mechanism for an electric circuit breaker comprising an operating cylinder having a reciprocally operable piston for actuating said circuitbreaker, said cylinder having exhaust ports in the walls at the opposite ends thereof, at least one of said exhaust ports having a large cross sectional area for permitting high 1 speed reversal of said piston and corresponding reclosing movement of said circuit breaker, means for applying fluid pressure at the opposite sides of said piston, valve means coacting directly with said cylinder for controlling said exhaust ports so that reversal of said piston is not appreciably retarded by back pressure in said cylinder, and a lost motion connection between said piston and said valve means for opening an exhaust port at one end of said cylinder substantially at completion of a circuit controlling piston stroke toward the opposite end of said cylinder, said means also causing closing of the exhaust port at the piston end of said cylinder.

2. Pneumatic reclosing mechanism for an electric circuit breaker comprising an operating cylinder having a reciprocally operable piston for actuating said circuit breaker, said cylinder having exhaust ports at opposite ends thereof, means for applying fluid pressure at the opposite sides of said piston, a slide valve coacting directly with said cylinder for directly controlling said exhaust ports so that reversal of said piston is not appreciably retarded by back pressure in said cylinder, said slide valve being arranged to close the exhaust at one end of said cylinder while venting the opposite end, and a lost motion operative connection between said piston and slide valve for controlling said exhaust ports in accordance with circuit controlling operations.

3. Pneumatic reclosing mechanism for an electric circuit breaker comprising an operating cyl- -inder having a reciprocally operable piston for actuating said circuit breaker between open and closed circuit positions, said cylinder having exby back pressure in said cylinder, and means operatively relating said sleeve valve to said piston for actuating said valve substantially at the completion of a circuit controlling stroke for opening the exhaust at one end of said cylinder and clos- 5 ing the exhaust at the opposite end.

HANSHEINRICH VERSE.

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