US2418690A - Electric circuit interrupter - Google Patents

Description

April 8, 1947. BENNETT 2,418,690

ELECTRIC CIRCUIT INTERRUPTER Filed July 13, 1944 Figl. 5

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I nventor: Robert M. Bennett,

y His Attorney.

Patented Apr. 8, 1947 ELECTRIC CIRCUIT INTERRUPTER Robert M. Bennett, Ithan, Pa., assignor to General Electric Company, a corporation of New York Application July 13, 1944, Serial No. 544,705

Claims. 1

My invention relates to electric circuit interrupters and more particularly to circuit breakers oi the fluid operated, fluid blast type.

Circuit interrupters of the fluid operated, fluid blast type have come into extensive use during the last few years. Such circuit interrupters often include serially arranged interrupting contacts and disconnecting contacts with means for opening the disconnecting contacts only when the interrupting contacts are open. Such circuit interrupters have required complicated interlocking means either mechanical, electrical or pneumatic, between the disconnecting contacts and the interrupting contacts to insure that the interrupting or arcing contacts are in the open position when the disconnecting contacts are opened. My invention is concerned with an improved arrangement wherein there is no mechanical connection between the disconnecting contacts and the means for operating the same which is associated with the interrupting contacts, except when the interrupting contacts are in the open position.

It is an object of my invention to provide a new and improved fluid blast circuit interrupter.

It is another object of my invention to provide a circuit interrupting device in which the only connection to ground is an air line for supplying fluid under pressure.

It is another object of my invention to provide a new and improved circuit interrupting device employing serially arranged interrupting and disconnecting contacts in which a lost motion connection insures that the interrupting contacts are open before the disconnecting contacts are open.

It is another object of my invention to provide a new and improved fluid blast circuit interrupter in which the interrupting contacts are operated during every opening and closing operation, and serially arranged disconnecting contacts are opened after one operation of the interrupting contacts and closed after a successive operation of the interrupting contacts.

Further objects and advantage of my invention will become apparent as the following description 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 drawing, in which Fig. 1 is a schematic diagram partly in section of a circuit interrupting device embodying my invention shown in'the closedcirouit position.

while Fig. 2 is a partial View of Fig. 1 showing the circuit interrupter in the open non-current carrying position.

For explanatory purposes I have illustrated my invention as applied to a circuit breaker of the cross fluid blast type, such as is disclosed and claimed in U. S. Letters Patent 2,284,842, Prince et al., granted June 2, 1942, and assigned to the same assignee as the present application. As will become apparent from the following description, my invention is particularly applicable to such a breaker since it eliminates all openings except the exhaust passage through which flame or are gases may escape. It will be understood, however, that my invention is equally applicable to other types of circuit breakers of the fluid 0perated type, which may or may not employ a blast of fluid for are extinguishing purposes.

For the sake of simplicity and clearness I have illustrated my invention as applied to a single phase circuit breaker, but it should be understood that it would apply equally well to a polyphase circuit breaker. As illustrated in the drawing, I have disclosed a fluid blast, fluid operated circuit breaker I of the cross gas blast type, comprising a pair of relatively movable interrupting contacts 2 and 3, and serially arranged, relatively movable disconnecting or isolating contacts 4 and 5. The relatively separable interrupting contacts 2 and 3 comprise the stationary contact 2 and movable contact 3, arranged to draw an arc in an are extinguishing chamber or are chute 6. The stationary contact 2 is arranged to be connected to a suitable line terminal I and is provided with spring pressed contact fingers 8 and longer arcing contact fingers 9, while movable contact 3 is provided with an arcing tip I0 so that when the contacts separate an arc is drawn between arcing tip l0 and arcing fingers 9. Immediately after separation of the contacts one terminal of the arc is transferred by a blast of fluid. such as air or other gas issuing from conduit H, which is suitably connected through a blast valve 12 with a source of fluid under pressure l3, from contact fingers 9 to the contact M which is provided with a tip of arc-resistant metal. The fluid blast from conduit ll during the opening operation of the circuit interrupter I drives the arc in the arc chute 8 against the edges of a plurality of partitions l5 which partitions are mounted in the arc chute B transverse to the arc gap and the ends of which extend close to the path of movement of arcing tip ID of movable interrupting contact 3.

In order to produce relative movement between interrupting contacts '2 and 3, I provide a fluid motor comprising a cylinder l6 suitably fastened to are chute G as by fastening means I1. Reciprocatingly mounted within cylinder [8 is a piston 18 directly connected to movable interrupting contact 3. The working face of piston I8 is exposed to the fluid under pressure admitted to are chute whenever valve [2 is operated so that not only is reiative separation of contacts 2 and 3 caused but these contacts are surrounded by a blast of fluid under pressure which will extinguish any are drawn. The other side of piston 18 has extending lerefrom a conducting guide rod 19 which extends outside of cylinder 15. To insure good electrical connection between conducting guide rod i9 and cylinder I provide a plurality of contact fingers 28 mounted on cylinder l6 so as to be in sliding engagement with conducting guide rod IQ. The fingers 20 or cylinder 16 are electrically connected by means of a conductor 2| with the disconnecting or isolating contacts 4 and 5 to be described hereinafter and under normal conditions conductor 2| is the only connection of any kind whatsoever between the arcing contacts and disconnecting contacts of circuit interrupter i. A suitable sp ing 22 mounted within cylinder l6 biases interrupting contacts 2 and 3 to the closed position. It will be obvious then that the interrupting contacts are normally held in the closed position by spring means 22 and are opened only when blast valve I2 is open.

Relatively movable disconnecting contacts 4 and have been illustrated with the contact 5 as the stationary contact connected to the other line terminal 23. Disconnecting contact 4 is illustrated as a blade-type movable contact pivotally mounted at 24 to a stationary support 25, and electrically connected through conductor 2! with movable arcing contact 3. Movable disconnecting contact 4 is normally biased to the open position by means of a spring 26 and is adapted to be held in the closed position against the bias of spring 26 by means of a rotatable cam 22', pivotally mounted at 28 to a stationary support 29, which engages a crank 30 rigidly connected to pivotally mounted disconnecting contact 4. When cam 21 is in the position indicated in Fig. 1 disconnecting contact 4 is held in the closed position against the force of biasing spring 25. When cam 27 is in the position indicated in Fig. 2 disconnecting contact 4 is permitted to move to the open position under the force of spring 26.

Rotation of cam 21 to the positions indicated in Figs. 1 and 2, in order to determine whether the disconnecting contacts 4 and 5 are in the closed or open position, is obtained by means of a ratchet wheel 3! having a plurality of teeth 32, rotatably mounted with cam 21 about pivot 28. Ratchet wheel 3| is illustrated as having four teeth and consequently is rotated one-quarter revolution by means of a ratchet or pawl 33 associated with the end of guide rod 19 upon each operation of relatively movable arcing contacts 2 and It will be observed that the pawl and ratchet wheel arrangement described above is a sort of a lost motion connection by means of which the desired time delay or sequence is obtained, insuring that the interrupting contacts are in the open position before the disconnecting contacts are operated to the open position. The fluid motor comprising cylinder 15 and piston l8 therefore operates both the interrupting contacts and the disconnecting contacts. There is, however, a mechanical connection between the fluid motor and the disconnecting contacts only at the instant the disconnecting contacts are operated. At

4 all other times the only connection between the interrupting contacts and the disconnecting contacts is the current path 2| which connects them in series.

The operation of the circuit interrupter of my invention will b obvious from the detailed description included above. With the circuit breaker in the position indicated in Fig. 1 open operation is accomplished merely by opening blast valve l2 which produces relative separation of interrupting contacts 2 and 3 and simultaneously a blast of fluid in arc chute 6 to extinguish the arc drawn between contacts 2 and 3. Near the end of the opening stroke of piston i8 pawl 33 engages ratchet wheel 3| rotating it in a clockwise direction as viewed in Fig. l, to the position indicated in Fig. 2 whereupon spring means 26 causes high speed opening of disconnecting contact 4. As soon as the air is shut off by the closing of blast valve 12 spring 22 causes the interrupting contacts '2 and 3 to assume the closed position indicated and the breaker remains in the open position of Fig. 2.

To close the breaker blast opened and the interrupting contacts 2 and 3 operate in exactly the same manner as in an opening operation. In this case, however, the pawl 33 engages ratchet wheel 31 rotating it in the clockwise direction another quarter of a revolution whereby cam 2'! moves disconnecting contact 4 to the closed position. When valv i2 is again closed spring 22 will move interrupting contact 3 to the closed position to complete the circuit between line terminals 1 and 23.

From the above discussion it will be observed that my new and improved circuit interrupter comprises a very simple mechanism requiring control of a single valve for all operations. Every second time that air is admitted to are chute 6 the disconnecting contacts are closed and for all the other times that blast valve I2 is opened the disconnecting contacts are opened. The interrupting contacts are the first to open during a circuit interrupting operation and the last to close during a circuit closing operation. A blast of fluid surrounds the interrupting contacts during both the circuit closing and circuit opening operation.

t will be apparent to those skilled in the art, that my invention is not limited to the particular construction shown, but that changes and modifications may be made without departing from the spirit and scope of my invention, and I aim in the appended claims to cover all such changes and modifications.

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

1. In an electric circuit breaker, a pair of relatively movable interrupting contacts, a pair of relatively movable disconnecting contacts serially arranged with said interrupting contacts, means for causing relative s aration of interrupting contacts and for si iultanecusiy producing a blast of arc extinguishing fluid ad acent said interrupting contacts to extingur'h the are drawn therebetween, and means oper csponse to every other operation or" SELiL rrupting contacts for closing said disconnecting contacts.

2. In an electric circuit breaker, a pair of relatively movable interrupting contacts, a pair of relatively movable disconnecting contacts serially arranged with said interrupting contacts, a source of ,fiuid under pressure, a fluid motor responsive to the introduction of fluid under presvalve i2 is again sure from said source for causing relative separation of said interrupting contacts, means for mechanically connecting said fluid motor to said disconnecting contacts only when said interrupting contacts are in the open circuit position to cause operation of said disconnecting contacts.

3. In an electric circuit breaker, a pair of relatively movable interrupting contacts, a pair of relatively movable disconnecting contacts serially arranged with said interrupting contacts, a source of fluid under pressure, a fluid motor, valve means for controlling the flow of fluid from said source to said fluid motor for causing relative separation of said interrupting contacts and for simultaneously producing a blast of are extinguishing fluid adjacent said interrupting contacts to extinguish the are drawn therebetween, means responsive to alternate openings of said valve means for causing opening first of said interrupting contacts and then of said disconnecting contacts, and means responsive to all other openings of said valve means for causing opening of said interrupting contacts and closing of said disconnecting contacts.

4. In an electric circuit breaker, a pair of relatively movable interrupting contacts, a pair of relatively movable disconnecting contacts serially arranged with said interrupting contacts, a source of fluid, a fluid motor responsive to the introduction of fluid under pressure from said source for causing relative separation of said interrupting contacts, means for mechanically connecting said fluid motor to said disconnecting contacts anly when said interrupting contacts are in the open circuit position to cause opening of said disconnecting contacts.

'5. In an electric circuit breaker, a pair of relatively movable interrupting contacts, a pair of relatively movable disconnecting contacts serially arranged with said interrupting contacts, a source of fluid, a fluid motor responsive to the introduction of fluid under pressure from said source for causing relative separation of said in terrupting contacts, means for mechanically connecting said fluid motor to said disconnecting contacts only when said interrupting contacts are in the open circuit position to cause closing of said disconnecting contacts.

ROBERT M. BENNE'IT.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,351,903 Baker et al June 20, 1944 990,512 Barnum Apr. 25, 1911 2,287,039 Jansson June 23, 1942

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