US1732292A - Automatic reclosing circuit-breaker system - Google Patents

Description

Oct. 22, 1929. o. c. TRAVER AUTOMATIC RECLOSING CIRCUIT BREAKER SYSTEM Filed May 22, 1926 InVefibOr': Oliver" QTr-aver";

5 His Attorneg.

Patented Oct. 22, 1929 UNITED STATES PATENT OFFICE comramr, a conrona'rron or NEW Yo AUTOMATIC BECLOSING CIRCUIT-BREAKER SYSTEI Application filed Kay 22,

the reclosure of a circuit breaker when either of the circuits, which the circuit breaker connects together, is energized and the load con nected to the other circuit isnormal.

Another object of my invention is to provide an automatic reclosing circuit breaker system for connecting two electric circuits toget-her when either of the two circuits are energized and a predetermined stub-end feed condition or a predetermined multiple feed '20 condition exists on the other circuit.

My invention will be better understood from the following description, taken "in connection with the accompanying drawing, and its scope will be pointed out inthe appended claims.

In the accompanyingdrawing, which diagrammatically shows an automatic reclosing circuit breaker system embodying my invention, 1 represents a circuit breaker which is arranged to connect together the conductors 2 and 3 of two electric circuits. In order to simplify the drawing, it has been assumed that the ground constitutes the other side of each of the two circuits, but it is evident that my invention is not limited to grounded circuits, butis applicable to any electric system. The circuit comprisin the conductor 2 and the ground is adapte to be supplied by a suitable source 4 and the circuit comprising the conductor 3 and the ground is adapted to be supplied by a suitable source 5. As shown in the drawing, the circuit breaker 1 is a contactor having a coil 6, which when energized maintains the circuit breaker in its closed position. However, it is evident that any other type of circuit breaker, examples of which are well known in the art, may be used. The circuit of the coil 6 includes contacts 7 of an overload relay 8, the coil 9 of which is 1926. Serial No. 111,068.

so connected that it is ener zed in accordance with the current flowing through the main contacts of the circuit breaker 1 when it is closed. As shown, the coil 9 is connected in series with the conductors-2 and 3. The relay 8 is designed so that it opens its contacts when the current through the coil 9 exceeds a predetermined value. The relay 8 operates irrespectively of the direction of current through its winding so that it operates upon the occurrence of an abnormal load on either of the two circuits to efl'ect the opening of the circuit breaker 1.

After the circuit breaker 1 has been opened by an abnormal load condition on either of the two circuits, it is desirable to have the circuit breaker'reclosed as soon as feasible after the abnormal condition has been-removed. It is well known in the art, however, that, in order for the reclosing equipment to control properly the reclosing of the clrcuit breaker, it is necessary to have the circuit breaker reclose in response to one electric condition of the abnormal circuit when it is not being energized independentl of the normal circuit, i. e., under stub-end eed conditions,

and to be reclosed in response'to another electric condition of the abnormal circuit when it is being energized independently, i. e., under multiple feed conditions.

For accomplishing the above results, I provide a load indicating resistor 10 which is arranged to be connected in series with the conductor 2 and 3 when the circuit breaker is open so as to limit to a relatively small value t e amount of current that flows from the normal circuit into the abnormal circuit; a reclosing relay 11 for controllin the reclosing of the circuit breaker 1 un er stub-end feed conditions of the abnormal circuit, a reclosing relay 12 for controlling the reclosin of the circuit breaker 1 under multiple fee conditions of the abnormal circuit; a selective relay 13 which determines which of the two reclosing relays controls the-reclosing, and .a

' transfer rela 14 for controlling theconnections of the c osing coil so that it is completed across whichever circuit is energized when the circuit breakeris open and only one of the circuits is independently energized.

The reclosingrelay 11 is connected and arranged in such a manner that it is controlled in accordance with the sum of and the difference between the voltages of the two circuits, and operates irrespectively of 'which side .has the faulty condition convoltage across the circuit comprising theconductor 2 and ground, and the coils 17 and 19 are connected in any suitable manner so that they are energized in accordance with the voltage across the circuit comprising the conductor 3 and ground. As shown in the drawing, coils 16 and 18 are arranged 6'59 connected in series between conductor 2 and ground and coils 17 and 19 are arranged to be connected in series between conductor 3 and ground when the selective relay contacts 21 are closed. The coils 16 and 17 are shown wound around the same core and are arranged accumulatively so that the combined eflect thereof varies as the sum of the voltages of the two electric circuits. The coils 18 and 19 are shown wound around the opposing core and are arranged differentially so that the combined effect thereof varies as the difference between the voltages of the two electric circuits. The coils 16 and 17 are arranged to close the relay contacts 20 when the difference between the sum of and the difference between the voltages of the two circuits is greater than a certain amount.

It will be observed that by my arrangement of windings the relay operates irrespectively of which side has the abnormal condition, since with a given voltage on either side and another given voltage on the other, the sum of the voltages, the difference betweenthe voltages and the difference between the sum and difference are the same in both cases. For example, if one circuit has 300. volts across it, and the other has 20 volts across it, or vice versa, the sum is always 320 volts, the difference is always 280, and the difference between the sum and difference, whichis the value in response to which the relay 11 operates, is always volts.

The contacts 20 of the reclosing relay 11' are in a circuit for closing coil 6 which also includes the contacts 21 of the selective reranged in any suitable manner so that its contacts 21 are closed only under stub-end feed conditions of the faulty circuit. As

close its contacts 22, which are in another circuit for the closing coil 6, under certain multiple feed conditions of the faulty circuit. As shown, the coil of the relay 12 is connected in parallel with the coil of the selective relay 13, but the relay 12 is designed to open its contacts 22 in response to a much lower difference in voltage between the two electric circuits than the difference required to pick up the relay 13. Under multiple feed conditions of the faulty circuit, the voltage across the faulty circuit is much higher for a given load than under stub-end feed conditions, so that the selective relay 13 is not sufficiently energized to close its contacts 21. Therefore, the relay 11 cannot effect the closing of the circuit of the closing coil 6. As the abnormal condition on the faulty circuit is removed, the voltage of the faulty circuit increases so that voltage impressed upon the winding of the relayv 12 decreases. At a predetermined value, the relay 12 closes its contacts 22 and completes the circuit for the closing coil 6.

It will be observed that the relays 12 and 13 are so connected and arranged that their operation is the same irrespective of which circuit has the abnormal load condition connected thereto.

The coil of the transfer relay 14 is arranged to be connected between the conductor 3 and ground by auxiliary contacts 24 on the circuit breaker 1 when it is in its open position. If the voltage between conductor 3 and ground is approximately normal, the relay 14 3 and ground after the breaker opens, relay '14 remains in the posit-ion shown, in which position its contacts 26 connect the closing coil 6 so that'its circuits are completed between conductor 2 and ground- Therefore, by means of relay 14, the closing coil 6 always has approximately normal voltage impressed thereon during the closing operation.

Any suitable means, examples of which are well known in the art, may be provided for preventing the circuit breaker from being reclosed within a certain length of time after the breaker opens. As shown in the drawing, this result is obtained by means of a dashpot 23 which prevents the overload relay from closing its contacts? until a predetermined time after the circuit breaker opens.

The operation of the system shown is as follows: So long as the circuit breaker is closed and there are normal loads connected to both circuits, the circuit breaker 1 remains closed. The circuit of the closing coil 6 is from conductor 2 through resistor 31, contacts 26 of relay 14, closing coil 6, overload relay contacts 7, contacts 22 of the relay 12, to ground.

When an overload occurs on either circuit which is sufficient to cause the overload relay 8 to open its contacts 7, the coil 6 is deenergized and the circuit breaker 1 opens. If the abnormal condition is between conductor 3 and ground, the transfer relay 14 does not pick up when its circuit is completed by the auxiliary contacts 24 on the circuit breaker. If the abnormal condition is between conductor 2 and ground, and the source 5 is in service, relay 14 is sufficiently energized, when its circuit is completed, to open its contacts 26 and close its contacts 25. A

predetermined time after the circuit breaker opens, the overload relay recloses' its contacts 7 inthe circuit of the closing coil 6.

Let it be assumed that the abnormal condition occurs between conductor 3 and ground so that the relay 14 does not pick up. If the source 5 is not in service when the circuit breaker 1 opens, the voltage across the circuit comprising conductor 3 and ground is very low, so that substantially normal voltage is impressed upon the coils of relays 12 and 13. Both of these relays pick up, so that the contacts 22 are opened and the contacts 21 are closed. If, however, multiple feed conditions exist on the faulty circuit after the breaker opens, that is, the source 5 is connected thereto, there is sufficient voltage across thefaulty circuit so that only the relay 12 picks up. The relay 13 maintains its contacts 21 open so that the stub-end reclosing relay cannot effect the reclosing of the circuit breaker.

conditions exist on the faulty circuit, that is, the source 5 is-not in service, so that relay 13 closes its contacts 21 and thereby connects coils 16 and 18- between conductor 2 and ground, and connects coils 17 and 19 between conductor 3 and ground. After the circuit breaker opens, a very small current is supplied from the source 4 through resistor 10 .to the faulty circuit. This small current produces a voltage drop across the load circuit and this voltage drop varies with the resistance of the load. Therefore, as the load resistance varies, the voltage impressed upon the coils 17 and 19 of the stub-end reclosing relay varies accordingly. So long as the re- First it will be assumed that stub-end feedsistance of the load across the fault circuit I is less than a certain value, the pul exerted by the coils 16 and 17 is not sufficient to close the contacts 20 of the relay 11 against the bias ofvthe spring 40 and the pull exerted by the coils 18 and 19. As the load resistance increases, the combined force exerted by the coils 16 and 17 increases, and the combined force exerted by the coils l8 and 19 decreases. When the load resistance increases to such a value that the difference between these two combined forces is more than a certain value, the relay contacts 20'are closed and a circuit is completed for the closing'coil 6 of the 'circuit breaker from the conductor 2, through contacts 26 of the transfer relay 14, closing coil 6, overload relay contacts 7, contacts 20 of reclosing relay 11, contacts 21 of selective relay 13 to ground. When the circuit breaker closes, its main contacts short circuit the coil of relay 12 so that its contacts 22 are closed and complete the heretofore described holding circuit for the closing coil 6 to maintain the circuit breaker in its closed position. The main contacts of the circuit breaker also short circuit the coil of the relay 13, which is restored to the position shown in the drawing. The opening of the contacts 21 effects the opening of the circuits of the coils of the reclosing relay 11 so that the spring 40 restores the relay to the position. shown.

If the source 5 is connected to the faulty circuit when the circuit breaker 1 opens, the relay 12 picks up and opens its contacts 22, but relay 13 does not pick up so that the reclosing relay 11 is inoperative to effect the reclosing of the circuit breaker. So long as the load is such that the'voltage difference between the two circuits is more than a certain value, the relay l2 maintains its conconductor 2 through contacts 26 of transfer relay 14, closing coil 6, overload relay contacts 7 contacts 22 of reclosing relay 12 to ground. Afterthe circuit breaker closes, the

various control devices are restored to their normal condition in the manner heretofore described,

It will be obvious from the drawing and the above description that the reclosing equipment operates in the same manner when the fault is between conductor 2 and ground and the circuit comprising conductor 3 and ground is energized by source 5, except that relay 14 is picked up by the opening of the circuit breaker so. that the closing coil 6 is connected between conductor 3 and .ground during the closing operation. As soon as circuit breaker 1 closes, the relay 14 is restored to its normal position so that the closing coil is reconnected between conductor 2 and ground.

In order to prevent the closing coil 6 from being momentarily deenergized while the transfer relay is moving from its energized to its deenergized position, the relay 14 may be designed in any suitable manner, so that its contacts 26 are closed before the contacts 25 are opened. 'With such an arrangement. however, the conductors 2 and 3 are connected together for an instant, through the contacts 25 and 26 of the relay 14. In order to limit the current, that flows from one conductor to the. other through this momentarily closed circuit, to a value within the capacity of the contacts 25 and 26, suitable current limiting means may be provided therein. As shown in the drawing, this result is obtained by means of a resistor 30 connected between the conductor 3 and the contacts 25, and a similar resistor 31 is connected between the conductor 2 and the contacts 26. It is evident, however, that either one of these resistors may be omitted, provided the resistor which is left is such as to limit the current to the desired value.

IVhile I have, in accordance with the provisions of the patent statutes, shown and described my invention as applied to a particu lar 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 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 an automatic reclosing circuit breaker system, two electric circuits, a circuit breaker connecting said circuits together, means for effecting the opening of said circuit breaker, and means controlled in accordance with the sum of and the difference between the voltages of the two circuits for I effecting the reclosing of the circuit breaker.

2. In an automatic reclosing circuit breaker system, two electric circuits, a circuit breaker'connecting said circuits together, means for effecting the opening of said 011- cuit breaker, and means responsive to a pre- .determined difference between the sum of cuits and to exert an opposing force in accordance with the difference between the voltages of the two circuits.

4. In an automatic reclosing circuit breaker system, two electric circuits, a circuit breaker connecting said ciruits together, means for effecting the opening of said circuit breaker, and a balance relay for effecting the reclosure of said circuit breaker comprising a pivoted member, two coils respectively connected across said electric circuits and arranged to exert a force which tends to move said member in one direction and which varies in accordance with the sum of the voltages of the two circuits, and two other coils respectively connected across said electric circuits and arranged to exert a force which tends to move said member in the opposite direction and which varies in accordance with the difference between the voltages of said circuits.

5. In an automatic reclosing circuit break er system, two electric circuits, a circuit breaker connecting said ciruits together, means for effecting the opening of said circuit breaker when a'predetermined abnormal condition occurs on either of said circuits and means for effecting the reclosure of said circuit breaker when the abnormal condition has been removed from the faulty circuit and the other circuit is energized including a current limiting device arranged to be connected between said circuits when the circuit breaker is open,

and a relay controlled in accordance with the a sum of and the difference between the voltages of the two circuits.

6.- In an automatic reclosing circuit breaker system, two electric circuits, a circuit breaker connecting said ciruits together, means for effecting the opening of said circuit when a predetermined abnormal condition occurs on either of said circuits, and means for effecting the reclosure of said circuit breaker when the abnormal condition has been removed from the faulty circuit and the other circuit is energized including a current limiting device arranged to be connected between said circuits when the circuit breaker is open and a differential relay having a pivoted member, two coils connected across one of said circuits so as to be energized in accordance with the voltage thereof and two coils connected across the other of said circuits so as to be energized in accordance with the voltage thereof, one

of said first mentioned two coils being arranged with one of said second mentioned two coils so that they exert a combined force on said pivoted member which tends to move it in one direction and which varies in accordance with the sum of the voltages of the two circuits and the other two of said coils being arrangedso that they exert a combined force on 'said pivoted member which tends to move it in the opposite direction and which varies in accordancewith the difference between the voltages of the two cit-cuits.

7 In an automatic reclosing circuit breaker system wherein a circuit breaker 1s arranged to connect a source of current to a circuit under stub-end and multiple -feed conditions thereof, the combination of means controlled by an electrical condition of said circuit for effecting the reclosure of the circuit breaker under multiple feed conditions thereof, means for supplying a limited current to said circuit from said source when the circuit breaker is open, and means controlled in accordance with the sum of and the difference between the voltages of the source and said circuit for effecting the reclosure'of the circuit breaker under stub-end feed conditions of said circuit.

8. In an automatic reclosing circuit breaker system wherein a circuit breaker is arranged to connect a source of current to a circuit under stub-end and multiple feed conditions thereof, the combination of means controlled by an electrical condition of the circuit for effecting the reclosure of the circuit breaker under multiple feed conditions of the load circuit, means for supplying a limited current to said circuit from said source when said circuit breaker is open, means controlled in accordance with the sum of and the difference between the voltages of the source and said circuit for effecting the reclosure of the circuit breaker under stub-end feed conditions of said circuit, and means controlled b the voltage across said circuit for determining which of said reclosing means is to effect the reclosing of the circuit breaker.

9. In an automatic reclosing circuit breaker system wherein a circuit breaker is arranged to connect a source of current to a circuit under stub-end and multiple feed conditions thereof, the combination of means controlled by an electrical condition of the circuit for effecting the reclosure of the circuit breaker under multiple feed conditions of the circuit,

7 means for supplying a limited current to said circuit from said source when said circuit .breaker is open, means responsive to a predetermined difference between the sum of and the difference between the voltages of the source and the circuit for effecting the reclosure of the circuit breaker under stub-end feed conditions of the circuit, and means responsive to the difference between the voltages of the source and the circuit for rendering said stub-end reclosing means operative.

10. In an automatic reclosing circuit breaker system, two electric circuits, a circuit breaker connecting said' circuits together, means responsive to an abnormal condition on either circuit for effecting the opening of v circuits for effecting the reclosing of said cirvoltage difference between the two circuits exceeds a predetermined value.

11. In an automatic reclosing circuit breaker system, twoielectric circuits, a circuit breaker for connecting said circuits together, a closing coil for said circuit breaker, a circuit for said closing coil, means responsive to the difference between the voltages of said electric circuits for effecting the completion of said closing coil circuit when said voltage difference is below a predetermined value, a second circuit for said closing coil, contacts in said second circuit, means responsive to a predetermined difference between the sum of and the difference between the voltages of the two circuits for effecting the closing of certain of said contacts when said last mentioneddifference is more than a certain value, and means responsive to the difference between the voltages of the two electric circuits for effecting the closing of the other of said contacts when the voltage difference between said two electric circuits exceeds a predetermined value. y

In witness whereof, I have hereunto set my hand this 21st day of May, 1926.

I OLIVER C. TRAVER.

said circuit breaker, means responsive to the difference between the voltages of said circuits for effecting the reclosure of said breaker when said voltage difference is below a predetermined value, means responsive to a predetermined difference between the sum of and the difference between the voltages of thetwo

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