US2014949A - Automatic reclosing circuit breaker system - Google Patents

Description

Sept. 17, 1935, l NEHER 2,014,943

AUTOMATIC RECLOSING CIRCUIT BREAKER SYSTEM Filed Sept. 2'7, 1934 Inventor: John H. Neher,

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Patented Sept. 17, 1935 PATENT OFFICE AUTOMATIC RECLOSING CIRCUIT BREAKER SYSTEM John H. Neher, Merion, Pa., assignor to General Electric Company, a corporation of New York Application September 27, 1934, Serial No. 745,711

4 Claims.

My invention relates to automatic reclosing circuit breaker systems and its object is to provide an improved arrangement for effecting a single reclosure of a circuit breaker which is simple and inexpensive.

My invention will be better understood from the following description when taken in connection with the accompanying drawing which diagrammatically illustrates an automatic reclosing circuit breaker system embodying my invention, and its scope will be pointed out in the appended claims.

Referring to the drawing, I represents a circuit breaker which is arranged to connect a supply circuit 2 to a load circuit 3. The circuit breaker I may be of any suitable type, examples of which are well known in the art. As shown in the drawing, the circuit breaker I is of the well known latched-in type and includes a closing coil 4 which, when energized, closes the circuit breaker I, and a trip coil 5 which, when energized, releases a latch 6 that holds the circuit breaker I in its closed position. As shown, the trip coil 5 is connected in series with the secondary winding of a current transformer I, the primary winding of which is connected in series with the circuits 2 and 3 when the circuit breaker I is closed. The trip coil 5 is arranged to effect the opening of the circuit breaker I when the current through the circuit breaker exceeds a predetermined abnormal value.

The circuit of the closing coil 4 is controlled by means of an auxiliary relay 8 of the well known hesitating type so that the circuit of the closing coil is maintained completed for a sufficient length of time to complete the closing operation of the circuit breaker.

In order to effect a single reclosure of the circuit breaker I when it is opened in response to the operation of the trip coil 5, I provide, in accordance with my invention, an instantaneous relay 9 and a time relay II] which are so interlocked electrically that they can efiect only one reclosure of the circuit breaker in case it opens immediately after the initial reclosure. This result is obtained by having the initial energizing circuit of the instantaneous relay 9 completed through the normally closed contacts II of the time relay I9 and having the circuit, which effects the closing of the circuit breaker, completed through the series-connected normally open contacts I2 of the instantaneous relay 9 and normally open contacts I3 of the time relay III. The relay I9 is designed in any well known manner so that when the operating winding of the relays 9 and I are simultaneously energized the relay I0 does not open its contacts II until after the relay 9 has closed its contacts I2 and has thereby completed a locking circuit for itself around the contacts II of the relay I9. Relay I0 is also arranged in any suitable manner so that it does not reclose its contacts II until after the operating winding of the relay I 9 has been deenergized for a predetermined length of time. For initiating the operation of the relays 9 and 10 I 0 in response to the opening of the circuit breaker I, I provide the auxiliary contacts I4 on the circuit breaker I. These auxiliary con- ,tacts I4, which are closed when the circuit breaker I is opened, are connected in series in the energizing circuits for the operating windings of the relays 9 and I0.

The operation of the arrangement shown in the drawing is as follows: When the circuit breaker I is closed and the current through the circuit breaker exceeds a predetermined value, the trip coil 5 releases the latch 9 and effects the opening of the circuit breaker. The closing of the auxiliary contacts I4 on the circuit breaker I completes an energizing circuit for the operating winding of the time relay I9 and an energizing circuit for the operating winding of relay 9 through the normally closed contacts II of the time relay III. Relay 9 immediately closes its contacts I2 and thereby completes a locking circuit for itself so that this relay does not become deenergized by the subsequent opening of the contacts II of the time relay I II. After a predetermined time interval, relay I9 opens its contacts II and closes its contacts I3, thereby com- 5 pleting a closing circuit for the relay 8 through the series connected contacts I2 and I3. By closing its contacts I5, relay 8 completes an energizing circuit for the closing coil 4 so as to eiTect the closing of the circuit breaker I. By 4 opening its auxiliary contacts I 4, the circuit breaker I interrupts the energizing circuits for the relays 9 and I9. Relay 9 immediately opens its contacts I2 but relay I 3 maintains its contacts II open for a predetermined time after its operating winding is deenergized. Therefore, if the circuit breaker I opens within a predetermined time after the initial reclosure thereof, the energizing circuit for the operating coil of relay I0 is reestablished to maintain the relay in its energized position, The reopening of the circuit breaker I under these conditions, however, will not efiect another reclosure thereof because the initial energizing circuit of the relay 9 is now open at the contacts I I of the relay Ill.

If, however, the circuit breaker I remains closed after the initial reclosure thereof, the relay III will, after a predetermined time interval, close its contacts H. The system then is operative to effect another time delay reclosure in response to the next opening of the circuit breaker I.

While I have, in accordance with the patent statutes, shown and described my invention as applied to a particular system and as embody ing various devices diagrammatically indicated, changes and modifications will be obvious to those skilled in the art, and I therefore aim in the appended claims to cover all such changes and modifications as fall within the true spirit and scope of my invention.

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

1. In combination, an electric circuit, a circuit breaker in said circuit, means for opening said circuit breaker in response to a predetermined abnormal circuit condition, and means for eflecting a single reclosure of said circuit breaker when it opens within a predetermined time after the first reclosure including an instantaneous relay having normally open contacts, a time relay having normally open contacts and normally closed contacts, a circuit for said instantaneous relay including said normally closed contacts of said time relay, means controlled by said circuit breaker for energizing said instantaneous relay circuit and said time relay in response to the initial opening of said circuit breaker, and a closing circuit for said circuit breaker, including said normally open contacts of both of said relays connected in series.

2. In combination, an electric circuit, a circuit breaker in said circuit, means for opening said circuit breaker in response to a predetermined abnormal circuit condition, and means for effecting a single reclosure of said circuit breaker when it opens within a predetermined time after the first reclosure including an instantaneous relay having normally open contacts, a time relay having normally open contacts and normally closed contacts, a circuit for said instantaneous relay including said normally closed contacts of said time relay, a circuit for said timing relay, contacts in said relay circuits controlled by said circuit breaker so that they are closed when said circuit breaker is open,

and a closing circuit for said circuit breaker 5 including said normally open contacts of both of said relays connected in series.

3. In combination, an electric circuit, a circuit breaker in said circuit, means for opening said circuit breaker in response to a predeter- 10 mined abnormal circuit condition, and meansv for effecting a single reclosure of said circuit breaker when it opens within a predetermined time after the first reclosure including an instantaneous relay having normally open con- 15 tacts, a time relay having normally open contacts and normally closed contacts, a circuit for said instantaneous relay including said normally closed contacts of said time relay, a circuit for said timing relay, contacts in said relay circuits 2O controlled by said circuit breaker so that they are closed when said circuit breaker is open, a locking circuit for said instantaneous relay including said normally open contacts of said instantaneous relay and said circuit breaker controlled contacts, and a closing circuit for said circuit breaker including said normally open contacts of both of said relays connected in series.

4. In combination, an electric circuit, a circuit breaker in said circuit, means for opening said circuit breaker in response to a predetermined abnormal circuit condition, and means for effecting a single reclosure of said circuit breaker when it opens within a predetermined time after the first reclosure including an instantaneous relay, a time relay having contacts which close a predetermined time after said time relay is deenergized, an energizing circuit for said instantaneous relay including said time relay contacts, means controlled by said circuit breaker for completing said energizing circuit for said instantaneous relay and an energizing circuit for said time relay in response to the opening of said circuit breaker, and means for completing a closing circuit including said normally open contacts of both of said relays connected in series for effecting the closing of said circuit breaker.

JOHN H. NEHER.

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