US1537727A

US1537727A - Automatic reclosing circuit-breaker system

Info

Publication number: US1537727A
Application number: US715726A
Authority: US
Inventors: Arvid E Anderson
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1924-05-24
Filing date: 1924-05-24
Publication date: 1925-05-12
Anticipated expiration: 1942-05-12
Also published as: DE579759C; GB234510A

Description

May 12, 1925. 1,537,727

A. E. ANDERSON AUTOMATIC REC/LOSING CIRCUIT BREAKER SYSTEM Filed May 24, 1924 Inventor- I AT'Vid B. Anderson,

His Attorney.

Patented May 12, 1925.

UNITED STATES 1,537,721 PATENT OFFICE.

ARVID E. ANDERSON, OF SCOTIA, NEW YORK, ASSIGNOR T0 GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW'YOBK.

AUTOMATIC RECLOSING CIRCUIT-BREAKER SYSTEM.

Application filed May 24,

To all whom it'ma'z concern:

Be it known that I, ARVID E. ANDERSON, a citizen of the United States, residing at Scotia, in the county of Schenectady, State of New York, have invented certain new and useful Improvements in Automatic Reclosin Circuit-Breaker Systems, of which the to lowing is a specification.

My invention relates to automatic reclosing circuit breaker systems.

In accordance with one of the automatic reclosing circuit breaker systems which is in extensive use at the present time, a circuit breaker is arranged to be reclosed automatically after it has been opened by an overload and has remained open for a certain length of time. If the overload is still present when the circuit breaker is reclosed the circuit breaker again opens and the above cycle of operation is repeated a predetermined number of times after which the automatic reclosing system is rendered inoperative. If at any time, while the automatic reclosing system is operative, the overload disappears, the circuit breaker remains closed when reclosed. In some cases the reclosing system is also arranged to be rendered inoperative in case of an excessive overload or short circuit, since the circuit breaker and other apparatus may be seriously damaged by opening and closing a circuit breaker under such severe abnormal conditions. In arrangements which have been used heretofore for accomplishing this result it has been necessary for the operator or some other person to release certain switches or relays in order to render the automatic reclosing system; operative again to control the reclosing of the circuit. Therefore it is evident that in cases where continuity of service is very desirable these arrangements are not entirely satisfactory because the circuit breaker may remain open longer than is necessary so far as the load conditions are concerned.

One object of my invention is to provide an automatic reclosing circuit breaker system in which the automatic reclosing means is rendered inoperative to reclosethe circuit breaker when the abnormal condition ex ceeds a predetermined value and the automatic reclosing means is rendered operative again to .close the circuit breaker when the abnormal condition has disappeared.

My invention will be better understood 1924. Serial No. 715,726.

from the following description when taken n connection with the accompanying draw- 1ng, which diagrammatically shows an automatic reclosing circuit breaker system embodying my invention, and its scope will be pointed out in the appended claims.

Referring to the drawing, 1 represents a source of current shown as a generator, which is arranged to be connected to a load circuit 2, by means of a circuit breaker 3 of any well known type. The load circuit 2 is also arranged to be supplied by one or more other sources 1'.

In order to simplify the drawing, it is assumed that the ground is one side of the load circuit. One terminal of the generator 1 is shown directly connected to ground and the circuit breaker 3 is arranged to connect the other terminal to the metallic conductor of the load circuit. It is evident, however, that my invention is neither limited to a grounded system nor to having the circuit breaker 3 control the connector between only one terminal of the generator and the corresponding side of the load circuit.

As shown, the circuit breaker 3 is of the well known latched-in type having a closing coil 4 which, when energized, closes the circuit breaker, and a trip coil 5 which, when energized releases the latch 6 that holds the circuit breaker in its closed position. The trip coil 5 is arranged to be connected across a suitable source, such as the generator 1, by means of an overload relay 7 when the current supplied by the generator 1 exceeds a predetermined value.

For automatically reclosing the circuit breaker 3 after the circuit breaker opens in response to an overload, which does not exceed a predetermined amount, I provide a reclosing relay 8, which is arranged to be energized after the circuit breaker opens and which, after a predetermined time, completes the circuit of the hesitating control relay 9, which in turn completes the circuit of the closing coil 4 to close the circuit breaker.

Each time the circuit breaker 3 opens a notching relay 10 is energized. This relay is arranged to open the circuit of the reclosing relay 8, after the circuit breaker has been opened a predetermined number of ,times. The contacts of the notching relay are preferably arranged so that they can be reset only by hand so that when they are opened by the notching relay the reclosing relay 8 is rendered inoperativeto reclose the circuit breaker.

Relay 11 is an auxiliary relay for the c1rcuit breaker which operates when the circuit breaker 3 opens, to efiect the operation of certain other relays of the system in a manner hereinafter described.

In order to prevent the reclosingrelay 8 from operating to close the circuit breaker 3 after an excessive overload or short circuit has occurred, a lockout relay 12 isprovided, the circuit of which is arranged to be completed by means of a second overload relay 14 which is set to operate in response to a higher value of current than the overload relay 7. The lockout relay 12 is arranged in any well known manner so that after the coil of the relay 12 has been energized to prevent the operation ofthe reclosing relay 8, the subsequent deenergi'zation of the relay 12 does not render the reclosing relay 8 again operative. As shown, a latch 13 is provided for holding the relay 12 in its energized position.

As shown the overload relays 7 and 14 are connected in series across a resistance shunt in the circuit of the "generator 1 but it is evident that the windings may be connected directly in series with the generator, or in any other well known manner, so that they are energized in accordance with the amount of current supplied by the generator 1.to the load circuit 2.

In order to insure that the lockout relay 12 has time to operate before the circuit breaker 3 opens, the overload relays 7 and 14 are preferably arranged so that the relay 14 operates to effect the operation of the lockout relay 12 before the relay 7 eifects the opening of the circuit breaker. This may be accomplished in any well known manner as by making the overload relay 14 a substantially instantaneous relay and the relay 7 a time relay.

In order to render the reclosing relay 8 operative to reclose the circuit breaker 3 after the lockout relay 12 has been ener ized and the excessive overload, which cause the relay 12 to be operated, has disappeared I provide a relay 16 which is connected across the load circuit and which is arranged to complete the circuit of a releasemagnet 17 to release the latch 13 of the lockout relay 12 when the voltage across the load circuit exceeds a predetermined value. It will be evident that in case of a short circuit or an excessive overload the voltage across the load circuit, due to the load circuit being energized at some other point, is low. When, however, the short circuit or excessive overload has disappeared, substantially normal voltage is restored so that the volt-l age across the load circuit isan indication of the condition of the load circuit. Therefore by setting the rela 16 so that it operates to release the late 13 of the lookout relay 12 when the voltage across the load circuit is above a predetermined value, the automatic reclosing system is rendered operative to control the reclosin of the circuit breaker when the severe a normal condition has disappeared.

The operation of the system shown is as follows: When the circuit breaker 3 is closed and the load conditions are normal so that neither one of the overload relays 7 and 14 is sufiiciently energized to close 1ts contacts, the circuit breaker is held in its closed osition by the latch 6 and the apparatus is in the osition shown in the drawing.

hen an overload occurs, the overload relay 7 operates with a time relay delay to close its contacts 20. If the overload is severe enough the overload relay 14 also operates and closes its contacts 21. As heretofore described, the relay 14 is preferably arranged so that it operates more quickly than the relay 7 in order that the contacts 21 may be closed before the contacts 20 in case of a severe overload.

It will first be assumed that an overload occurs which causes the relay 7 to operate but does not cause the relay 14 to operate. The closing of the contacts 20 of the overload relay 7 completes a circuit for the trip coil 5 to trip open the circuit breaker 3. This circuit is from the ungrounded terminal of the generator 1 through-the trip coil 5, auxiliary contacts 22 on the circuit breaker, which are closed when the circuit breaker is closed, conductor 23, contacts 20 of the overload relay 7 to the ground.

When the circuit breaker 3 opens, the opening of its auxiliary contacts 24 opens the circuit of the auxiliary relay 11 which is connected across the generator 1 when the circuit breaker is closed. The rela 11, when deenergized, closed three sets 0

contacts

26, 27 and 28.

The closing of the contacts 26 connects the relay 16 across the load circuit 2. If the voltage across the load circuit 2 is above a predetermined value the relay 16 closes its contacts 29 and completes a circuit from the ungrounded terminal of the generator 1 through the contacts 29 of the relay 16, resistor 30, conductor 31,

contacts

32 and 33 of the lockout relay 12, conductor 34, contacts 27 of the relay 11 to ground. The release coil 17 of the lockout relay 12 is connected across the

conductors

31 and 34, but since the overload is assumed not to be severe enough to operate the lookout relay, the

contacts

32 and 33, which are arranged to connect the

conductors

31 and 34 directly to ether, short circuit the release coil 17. I the voltage across the load circuit is not high enough to operate the relay 16 after the circuit breaker 3 opens, the

above described circuit remains open. It will be evident from the following description that when only the overloa relay 7 is operated, the rela 16 has noefi'ect u on the operation of t e automat1c reclosing system so that the circuit breaker 3 is reclosed irrespectively of the position of the relay 16.

The closing of the contacts 27 of the relay 11 completes the circuit of the reclosing relay 8 and the notching relay 10. T1115 circuit is from the ungrounded terminal of the generator 1 through the contacts of the notching relay 10, conductor 36, coil of the notching relay 10, conductor 37, 0011 of the reclosing relay 8, conductor 38,

contacts

39 and 32 of the lockout relay 12, conductor 34, contacts 27 of the relay 11 to ground. The reclosing relay 8 is arranged in any suitable manner, as by means of a dash pot 40, so that it does not close its contacts 41 until a predetermined time after the coil of the relay is energized.

The notching rela 10 is arranged in any suitable manner so t at it does not open its contacts 35 until after the coil of the relay has been energized a predetermined number of times. This relay is also preferably arranged so that the coil of the relay has to be energized successively a predetermined time with less than a redetermined time between successive energizations in order to open the contacts 35.

As shown in the drawing, the plunger 43 of the notching relay 10 is arranged to actuate a ratchet 44, against the action of a spring 45, and a time delay device 46 such as a dash pot or a bellows. The rela is also provided with a holding pawl 47 w ich is normally held out of engagement with the ratchet 44 by the weight of the movable element of the time delay device 46 so that the ratchet can be rotated to its normal position by the spring 45, and which is arranged to be moved into engagement with the ratchet 44 by a spring 48 when the time delay device 46 is actuated by the plunger 43. The time delay device 46' is preferably arranged so that only the downward movement of the movable element thereof is delayed. An arm 49 is attached to the ratchet 44 and is normally held against a stop 50 by the spring 45. When the coil of the relay 10 is energized successively a predetermined number of times with less than a predetermined time between successive energizations which is sufficient to allow the time delay device 46 to return to its normal position, the arm 49 o ens the contacts 35 which are arranged to e held in their open position until they are manually reset.

When the above described circuit for the coils of the notchin relay 10 and the reclosing relay 7 is c osed, the energization of the coil of the notching relay 10 moves the ratchet 44 the distance of one tooth and moves upward the movable element of the time delay device 46. The spring 48 then moves the holding pawl 47 into engagement with the ratchet 44 so that the ratchet is held in its actuated position after the coil of the relay is deener ized.

After the circuit 0 the coil of the reclosing relay 8 has remained closed for a certain length of time, the relay 8 closes its contacts 41 and completes the circuit of the hesitating control relay 9. This circuit is from the ungrounded terminal of the generator 1, through the coil of the relay 9, conductor 52, contacts 41 of the reclosing relay 8, conductor 53, contacts 28 of the relay 11 to ground. The hesitating control relay, by closing its contacts 54, connects the closing coil 4 of the circuit breaker directly across the generator 1.

The energization of the closing coil 4 closes the circuit breaker 3 and if the overload has disappeared, the circuit breaker remains in its closed position. The closing of the circuit breaker completesthe circuit of the auxiliary relay 11 which opens its three sets of

contacts

26, 27 and 28. The opening of these three sets of contacts deenergizes the

relays

8, 9, 10 and 16 which return to their normal positions. The hesitating control relay 9, however, is arranged in any well known manner'so that it does not open its contacts 54 until after the coil of the relay 9 has been deenergized for a certain length of time. In this manner it is insured that the circuit of the closing coil 4 remains energized for a suflicient length of time to close the circuit breaker.

If the overload is still connected to the load circuit 2 when the circuit breaker 3 is reclosed, the overload relay 7 operates again and the above cycle is repeated except that the notching relay 10 is moved the distance of another tooth each time the circuit breaker opens. If the overload does not disappear, this cycle is repeated a predetermined number of times after which the notching relay 10 opens its contacts 35 which are in the circuit of the reclosing relay 8. Since the cont-acts 35 have to be reset by hand, further automatic reclosin of the circuit breaker is prevented unti these contacts are reset by the operator or some other person.

It will now be assumed that the overload that causes the overload relay 7 to close its contacts is also severe enou h to cause the overload relay 14 to close its contacts 21. The overload relay 7 eflects the opening of the circuit breaker 3 in the manner heretofore described, but before this occurs, the closing of the contacts 21 completes a circuit for the coil of the lookout relay 12.

This circuit is from the ungrounded terminal of the generator 1 through the auxiliary contacts 24 on the circuit breaker 3,

conductor 57, coil of the lockout relay 12,

conductor 58, contacts 21 of the overload relay 14 to ground, Since the lockout relay 12 is held in its energized position by the latch 13, the subsequent deenergization of the coil of the relay 12, when the circuit breaker opens,'does not cause the relay to reclose its

contacts

32, 33 and 39. Since the

contacts

39 and 32 are in the circuit of the reclosing relay 8, it is evident that so long as the lookout relay 12 is held in its energized osition the automatic reclosing system is inoperative to reclose the circuit breaker.

The lockout relay 12 remains in its energized position until the relay 16, which is connected across the load circuit by contacts 26 of the relay 11 after the circuit breaker opens, is sufficiently energized to close its contacts 29. The relay 16 is preferably set so that it operates only when the voltage across the load circuit is substanent statutes, shown and described my invention as applied to a particular system and as embodying various devices diagrammatically indicated, changes and modifications will be obvious to those skilled in the art and I, therefore, aim in the appendedclaims to cover all such variations and modifications as fall Within the true spirit and scope of my invention.

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

1. In an automatic reclosing circuit breaker system, a source of'current, a load circuit, a circuit breaker arranged to connect said source to said load circuit, means operative when said circuit breaker is open to effect the automatic reclosing of said circuit breaker, means responsive to a predetermined overload condition of said load circuit for rendering said automatic reclosing means inoperative to reclose said circuit breaker, and means operative in response to a predetermined condition of said load circuit for automatically rendering said reclosing means operative to reclose said circuit breaker subsequently to said reclosing means having been rendered inoperative.

2. In an automatic reclosing circuit breaker system, a source of current, a load said circuit breaker subsequently to said reclosing means having been rendered inoperative.

3, In an automatic reclosing circuit breaker system, a source of current, a load circuit arranged to be supplied with current at a plurality of points, a circuit breaker arranged to connect said source to said load circuit, overload responsive means for effecting the opening of said circuit breaker, means for automatically reclosing said circuit breaker after being opened by said overload responsive means, overload responsive means operative in response to a greater overload than said first mentioned overload responsive means for rendering said automatic reclosing means inoperative, and means responsive to the voltage of said load circuit for automatically rendering said automatic reclosing means operative after having been rendered inoperative by said second mentioned overload responsive means.

4. In an automatic reclosing circuit breaker system, a. source of current, a load circuit arranged to be supplied with current at a plurality of points, a circuit breaker arranged to connect said source to said load circuit, overload responsive means for etfecting the opening of said circuit breaker. a reclosing relay arranged when energized to effect the closing of said circuit breaker, a circuit for said relay, means operative in response to the opening of said circuit breakertocomplete said reclosing relay circuit, a lockout relay operative to interrupt said reclosing relay circuit upon the occurrence of a greater overload than is required to operate said overload responsive means, and resetting means for said lockout relay controlled by the voltage of said load circuit.

5. In an automatic reclosing circuit breaker system. a source of current, a load circuit arranged to be supplied with current at a plurality of points, a circuit breaker arranged to connect said source to said load circuit, time delayed overload responsive means for effecting the opening of said cir- "cuit breaker, a. reclosing relay arrangedl when energized to effect the closing of said circuit breaker, a circuit for said relay.

lUO

means operative in response to the opening of said circuit breaker to complete said reclosing relay circuit, a relay connected and arranged to interrupt said reclosing relay circuit upon the occurrence of a greater overload than isrequired to operate said overload responsive means, means for bolding said relay in its circuit interrupting position, a winding to effect the release of said holding means, and means for connecting 10 said winding across said load circuit after said circuit breaker opens.

In witness whereof, I have hereunto set my hand this 23rd day of May, 1924.

ARVID E. ANDERSON.