US1747096A - Automatic reclosing circuit-breaker system - Google Patents

Description

Feb. 11, 1930. w c w|- 1,747,096

AUTOMATIC RECLOSING CIRCUIT BREAKER SYSTEM Filed March 23, 1926 Inventor:

William C. White,

by g 2 K,/

His Attorney Patented Feb. 11, 1930 UNITED STATES PATENT OFFICE WILLIAM C. WHITE, OF SCI-IENEGTADY, NEW YORK, ASSIGNOR TO GENERAL ELECTRIC COMPANY, A CORPORATION OF NEW YORK AUTOMATIC RECLOSING CIRCUITBREAKER SYSTEM -App1ication filed March 23, 1926. Serial No. 96,841.

My invention relates to automatic reclosing circuit breaker systems, and particularly to such systems in which an electron discharge tube is used to control the reclosing 5 of a circuit breaker in response to a predetermined electrical condition of one of the circuits which are arranged to be connected together by the circuit breaker, and its object is to provide an improved system of this type.

In accordance with my invention, I control the reclosing of the circuit breaker by means of a two-element electron discharge tube which has its cathode so connected and arranged when the circuit breaker is open that its electron emission current varies the output of the tube in accordance with the load connectcd to one of the circuits. i

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

Referring to the drawing, which is a di agram of an automatic reclosing circuit breaker system embodying my invention, 1 and 2 represent two electric circuits which are arranged to be connected together by means of a circuit breaker 3. As shown in the drawing, 1 is a supply circuit to which is connected a suitable source of current 4, and 2 is a load circuit. The circuit breaker 3 may be of any suitable type, examples of which are well known in the art. -As shown, the circuit breaker 3 is of the well known contactor type comprising a coil 5 which, when energized, closes the circuit breaker and maintains it closed. The coil 5 may be energized from any suitable source of current. As shown, the coil 5 is energized from the supply circuit 1.

In order to effect the opening of the circuit breaker 3 when an overload occurs on the load circuit, an overload relay 6 is provided which has a coil 7 connected so that it is energized in accordance with the amount of current flowing from the supply circuit to the load circuit when the circuit breaker is closed. WVhen an excessive current flows from the supply circuit to the load circuit, the relay 6bpens its contacts 8, which are in the circuit of the coil 5 of the circuit breaker 3, so that the circuit breaker opens. After a circuit breaker has been opened due to an overload on the load circuit, it is desirable to reclose the circuit breaker automatically as soon as possible after the overload has been removed. In accordance with my improved arrangement, I accomplish this result by means of an impedance 8, shown as a resistor, which is connected in series between the supply and load circuits, when the circuit breaker 3' is open, so that a small load indicating current flows through the load, and a two-element electron discharge tube 9, which is arranged to be connected so that the current through it varies in accordance with the voltage drop produced across the load circuit by the load indicating current flowing through the load.

The two-element electron discharge tube 9 shown in the drawing is of the type'well known in the art as a kenotron, and comprises an evacuated receptacle containing a filamentary cathode 10 and a plate oranode 11. In order that the current through the tube may vary in accordance with the impedance of the load, the cathode 10 is arranged to be connected across the load circuit after the circuit breaker opens. The circuit of the cathode includes auxiliary contacts 12 on the circuit breaker which are closed when the circuit breaker is open, and contacts 13 of a time element relay 14, the coil 15 of which is connected across the load circuit 2. The relay 14 is designed so that it does not close its contacts 13 until after'the voltage across the load circuit has remained below a prede tcrmined value for a. predetermined time. The purpose of this time delay is to allow the load circuit voltage to reach a stable condition before the tube 9 is rendered responsive to the voltage across the load circuit. The plate 11 of the tube is connected to the supply circuit 3 and a relay 16 is connected in this circuit so that it is cnergiged in accordance with the output of the tube. The relay 16 is arranged to close its contacts 17 and'complete a circuit for the closing coil 5 of the circuit breaker 3 when the output of the tube exceeds a predetermined value.

The operation of the arrangement shown in the drawin is as follows:

\Vhen the circuit breaker 3 is closed, the holding circuit of the coil 5 is from the positive side of the supply circuit, through contacts 8 of the overload relay 6, coil 5, auxiliary contacts 18 on the circuit breaker 3 to the negative-side of the supply circuit. Upon the occurrence of an overload on the load circuit 2, the overload relay 6 opens its contacts 8 so that the circuit breaker 3 opens and removes the short-circuit from around the resistor 8.v The resistor 8' is of such 1 value that the voltage across the load circuit is reduced to such a low value that the relay 14 cannot maintain its contacts 13 open. After a predetermined time, the relay 14 closes its contacts 13 and completes a circuit for the cathode 10 across the load circuit. This circuitalsoincludes the auxiliary contacts on thecircuit breaker 3.

So-long as the impedance of the load connected across the load circuit is below a predetermined value, the voltage impressed upon the cathode 10 is not suflicient to cause enough current to flow through the relay 16 to pick it up. WVhen, however, the impedance of the load is above a predetermined value, the voltage impressed upon the cathode is high enough to cause sufiicient current to flow through the coil of the relay 16 so that it closes its contacts 17 and completes the energizing circuit of the closing coil 5 to close the circuit breaker. This circuit is from the positive side of the supply circuit, through contacts 8 of the overload relay 6, which are closed after the breaker opens, coil 5,contacts 17, to the negative side of the supply circuit. The'circuit breaker, in closing, completes its above-traced holding circuit for its closing coil, and by opening its auxiliary contacts 12,

disconnects the cathode 10 from across the' load circuit. As soon as the circuit breaker 3 closes, normal voltage is impressed upon the load circuit 2 so that the relay 14 opens its contacts 13. The relay 16 opens its contacts 17 after the circuit of the cathode 10 is opened atthe auxiliary contacts 12.

WVhile I have, in accordance with the patent statutes, shown and described my invention as applied to a particular system, and as embodying various devices j-diagrammatically indicated, changes andfmodifications will be connected in series between said circuits to limit the flow of current therebetween when the circuit breaker is open, a two-element electron discharge tube for controlling the reclosing of said circuit breaker comprising an anode and a cathode, means for connecting said cathode across said load circuit after said circuit breaker isopened, and means responsive to the current output of said tube for effecting the closing of said circuit breaker.

2. In an automatic reclosing circuit breaker system, a supply circuit, a load circuit, a circuit breaker connecting said circuits together, means for effecting the opening of said circuit breaker, an impedance arranged to be connected in series between said circuits to limit the flow of current therebetween when the circuit breaker is open, a two-element electron discharge tube for controlling the reclosing of said circuit breaker, comprising an anode and a cathode, timing means controlled by the voltage of said load circuit for connecting said cathode acrosssaid load circuit, and a control relay connected in the anode circuit of said tube for controlling the closing of said circuit breaker.

In witness whereof, I have hereunto set my hand this 22nd day of March, 1926.

lVILLIAM C. WHITE.

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, a supply circuit, a load circuit, a circuit breaker connecting said circuits together, means for effecting the opening of said circuit breaker, an impedance arranged to be

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