US2385041A - Control system - Google Patents

Description

Sept. 18, 1945. I w R, TAL|AFERRQ 2,385,041

CONTROL SYSTEM Filed April 23. 1943 WITNZSE INVENTOR yw u M/fi'am Rra/l'aflerm.

QED-21M I Patented Sept. 18, 1945 CONTROL SYSTEM William R. Taliaferro, Edgewood, Pa., assignor to Westinghouse Electric Corporation, East Pittsburgh, Pa.,, a corporation of Pennsylvania Application April 23, 1943, Serial No. 484,172

6 Claims.

My invention relates, generally, to control systerns. and it has reference, in particular, to automatic reclosing circuit breaker systems.

Generally stated, it is an object of my invention toprovide a control system for automatically reclosing a generator or feeder circuit breaker, which shall be simple and inexpensive to manufacture, easy to install and maintain, and accurate and certain in operation.

More specifically, it is an object of my invention to provide for combining the functions of the usual. reverse current relay and voltage directional relay in an automatic reclosing circuit breaker system in a single devicewithout losing any of the accuracy and certainty of operation of the usual separate arrangement.

It is also an object of my invention to provide for automatically reconnecting a directional responsive relay which is normally connected to operate in response to a reverse flow of current fiom one section of a feeder to another when the circuit breaker is closed, for preventing closure'of the circuit breaker when it is open unless the voltage difference between the sections is in a predetermined direction and is of a predetermined minimum value.

Another object of my invention is to provide for simplifying the present automatic reclosing circuit breaker system for generator or feeder application and reducing the number of devices required in the system, as well as the cost thereof, without reducing the efficiency and reliability of. the'system,

Still another object of my invention is to provide for connecting a calibrating resistor in series circuit relation with a control device disposed to be responsive to reverse current when the circuit breaker is closed, for operating the device in accordance with the direction and value of the voltage difference between the conductors to be connected by the circuit breaker, so as to prevent closure of the circuit breaker when the voltage,

difference is in the wrong direction or less than a,

' accordance with the voltage across the terminals of the circuit breaker when it is open for providing a sensitive voltage directional device.

For a more complete understanding of the nature and scope of my invention, reference may be made to the following detailed description and ill;

the accompanying. drawing, in which the single figure is a diagrammatic view of an automatic reclosing circuit breaker system embodying the principal features of the invention.

Referring to the single figure of the drawing, the reference numeral It! may denote generally an automatic reclosing circuit breaker system wherein a circuit breaker i2 is disposed to connect'adjacent sections [#4 and of a feeder connecting a'plurality of sources, such as the generators l6 and ll, to a load denoted generally by the numeral I8; Switches I9 and may be provided for selectively connecting the generators l6 and llto the feeder.

An overload relay 2| having an operating winding 22 connected for energization in response to the current flowing in the section l5 of the feeder, may be provided for controlling the operation of the circuit breaker l2 so as to open the circuit breaker upon the occurrence of a fault. An automatic control system, denoted generally by the numeral 24, may be provided for effecting reclosure of the circuit breaker I2 after the fault has been cleared.

The control system 24 may comprise generally load measuring means 23 of any type well known in the art. For example, a devicecomprising a disk 21 rotatably mounted on a shaft 28 provided with a movable contact arm 29 for selectively engaging one or another of the stationary contact members 30 and 3! and having opposed operating windings 32' and 33 for rotating the disk 21 in opposite directions through magnetic attraction for an insert 35 of magnetic material positioned on the disk may be utilized. A time delay action may be provided by using a damping magnet 36 for effecting a retarding torque against rotation of the disk. Provision may be made for normally connecting the operating winding 32 bemeasuring resistance 40 which is arranged to be connected by means of control switches 42 and 43 between sections I4 and I of the feeder.

In order to provide for connecting the windings 32 and 33 of the load measuring means to sections I4 and I 5 of the feeder in predetermined relation, an auxiliary reclosing relay 45 may be provided having an operating winding 49 which is arranged to be energized through the engagement of the moving contact arm 29 of the load measuring means with the stationary contact member 30.

Operation of the circuit breaker I2 may be effected by connection of the operating winding 48 thereof to section I4 of the feeder through the medium of a control relay 59 having an operating winding 5| which is disposed to be energized upon engagement of the moving contact arm 29 of the load measuring means with the stationary contact member 3| after the operating winding 33 has been connected to section I5 of the feeder and the load measuring means has determined that the voltage of section I5 of the feeder is suffioiently high for effecting the connection thereof to section I4.

In order to prevent closure of the circuit breaker I2 to connect section I5 of the feeder to section I4, when the voltage of section I5 is higher than that of section I4, and to open the 'circuit breaker I2 after it has closed, in the event that the flow of current through the circuit breaker is from section I5 to section I4, directional responsive means 55 may be provided.

The directional responsive means may be of any suitable type and, in this instance, a relay of the DArsonval type is illustrated. It comprises a stationary field magnet 56 which may be in the form of a permanent magnet, or may be, as shown, a relatively soft iron core having a magnetizing winding 51 normally connected between section I4 of the feeder and ground, through contact members 2Ia of the overload relay. The relay is also provided with a movable coil 59 for actuating a movable contact member 50 to engage one or another of the stationary contact members BI and 62. Springs 63 may be provided for maintaining the contact arm 80 in an intermediate position when the moving coil 59 is deenergized.

In order to prevent closure of the circuit breaker I2 should the voltage of section I5 be higher than that of section I4, the movable coil 59 may be connected by means of conductors 65 and 66 to sections I4 and I5 of the feeder in series circuit relation with a calibrating resistor 58 of such a value as to permit use of the device 55 as a sensitive voltage directional relay, responsive to the value and direction of the voltage between sections l4 and I5 of the feeder. The movable coil 59 my be so connected that, when the voltage of the section I4 is higher than that of section I5, the movable contact member 60 engages the stationary contact member 6| to complete an energizing circuit for the operating winding 5| of the control relay 50.

With a View to also using the device 55 after the circuit breaker is closed, as well as before, provision may be made for connecting the movable coil 59 for energization in accordance with the current through the circuit breaker, such as by connecting it to a shunt I0 interposed in section I4 of the feeder, by means of auxiliary contact members I2b associated with the circuit breaker I2. The contact members I2b may be so arranged that upon closure of the circuit breaker I2, the

control resistor 68 is shunted, and the movable coil 59 is connected directly across the shunt III.

The operating sequence of the automatic reclosing circuit breaker system hereinbefore described is as follows: On the occurrence of a fault, the operating Winding 22 of the overload relay 2| becomes sufficiently energized to operate the relay and open contact members 2 I a, thereby disconnecting the auxiliary reclosing relay 4'5 and the auxiliary contral relay from section I4 of the feeder. When the auxiliary control relay 50 returns to the deenergized position, the energizing circuit for the operating winding 48 of the circuit breaker I2 is interrupted through the opening of contact members 50a, so that the circuit breaker is deenergized. Opening of the main contact members I2a of the circuit breaker disconnects section I4 of the feeder from section I5 and deenergizes the overload relay 2|, which returns to the deenergized position.

Opening of the circuit breaker I2 completes an energizing circuit for the operating winding 32 of the load measuring means 26 through normally closed contact members I2c from section I4 of the feeder through control switch 42, conductor I2, contact members I2c of the circuit breaker, control resistor 13, conductor I4, operating winding 32, conductors I5 and IE to the other side of the line or ground. After a predetermined time delay, the movable contact arm 29 engage the stationary contact member 30 to establish an energizing circuit for the operating winding 46 of the auxiliary reclosing relay 45 extending from section I4 through control switch 42, conductor 11, contact members 2Ia of the overload relay, conductor I8, control resistor 89, operating winding 46, conductors 8| and 82, moving contact arm 29, stationary contact member 30, conductors I5 and IE to ground.

The auxiliary reclosing relay 45 operates and closes contact members 45c and 45d to provide holding circuits, and contact members 45a and 45b provide for connecting the load measuring resistor 40 to section I5 of the feeder through control switch 43 and for connecting the operating winding 33 of the load measuring means to the intermediate point 39 of the load measuring resistor.

If the voltage of section I5 is sufiiciently high under the condition when the generator I1 is connected to section I5, or the resistance of the load I8 is sufliciently high under the condition when the generator I1 is disconnected from section I5, the voltage applied to the operating winding 33 will be sufiicient to overcome the pull of operating winding 32, so that the disk 21 rotates in the direction for engagement of the movable contact arm 29 with the stationary contact member 3|.

In order to prevent closure of the circuit breaker I2 solely upon the determination that the voltage of section I5 is not greatly below that of section I4, the device may be so connected that the operating winding 5| of the auxiliary control relay 50 which controls the .energization of the operating winding 49 of the circuit breaker I2, cannot be energized unless the moving contact member engages stationary contact member 6 I, thus indicating that the voltage of section I4 is slightly greater than that of section I5, if generator I! is connected, or that there issome load on section I5 if it is not.

Under these conditions, an energizing circuit for the operating winding 5| of the auxiliary control relay 5!! is completed from section I4' thronghcontrol switch 42,. conductor" I1, contact members Zla of the overload relay 2|, conductor F8, control resistor 84, operating winding 5|, conductor 86, movable contact member 60, stationary contact member 61 conductor 8:1, contact memtZe of the circuit breaker I12, stationary contact: member 3t, and movable contact arm 29 oi the load measuring means, conductor 82, contact members 450 of the auxiliary reclosing relay and conductor 90 to ground.

1 Closure of the auxiliary control relay completes an energizing circuit for the operating winding. of the circuit breaker l2.through-contact members 50a efiecting closure of the circuit breaker.. A holding circuit for relay 50 is provided through. contact members 50b, resistor 84 and contact members Zla of the overload relay It. The operating winding 46" of the auxiliary reclosing relay 45 is deenergized by the shunt connection provided by the contact members 12d oilthe circuitbreaker.

When the circuit breaker l2 closes its auxiliarycontact members I2b are closed to connect the" moving coil 59 of the directional responsive means .55 directly across the shunt Ill, and also to shunt the control resistor 68. Should the direction of current flow reverse in section l4 so as to feed from generator l1 togenerator IS, the movable contact member of the device 55 will be actuated to engage the stationary contact member 62. The operating winding 5| of the auxiliary control relay 50 is thereby shunted so that the relay returns to the deenergized position. The operating winding 48 of the circuit breaker I2 is thereby disconnected from section ll of the bus through the opening of contact members 50a. The circuit breaker l2 becomes deenergized and opens to disconnect section M from section l5. Thereupon, the movable coil 59 is again connected inseries circuit relation with the calibrating resistor 68 across the terminals IZa of the circuit breaker l2 thereby becoming effective to prevent reclosing of the circuit breaker until the voltage of the generator I1 is reduced sufiiciently to prevent the reverse flow of current upon reclosure of the circuit breaker.

From the above description and accompanying drawing, it will be apparent that I have provided in a simple and effective manner for combining the functions of the usual separate reverse current and voltage directional relays in a single device. This has been accomplished in such a manner as to maintain the necessary accuracy and consistency of operation required for adequate protection of the system and apparatus protected by the circuit breaker. By practicing my invention, automatic reclosing circuit breaker systems may be greatly simplified and the manufacturing expense and maintenance thereof may be greatly reduced.

Since certain changes may be made in the above description, and different embodiments of the invention may be made without departing from the spirit thereof, it is intended that all the matter contained in the above description or shown in the accompanying drawing shall be considered as illustrative and not in a limitin sense.

I claim as my invention:

1. A control system for a circuit breaker disposed to connect a load circuit to a direct current source comprising, control means operable to effect operation of the circuit breaker a polarized relay having a pair of spaced contact members and a movable contact member actuated by an operating winding to engage one or another of the stationary contact members, a control. resistor; circuit means connecting. the operating winding.

and control resistor in series circuit. relation.

energization in accordance with the current through the circuit breaker when it is. closed, said. operating winding being effective when thus connected to actuate the movable contact member. to engage the other of the stationary contact members and efiect operation of the control means for opening the circuit breaker if the current flows from the load to the source.

2. The. combinationwith a circuit breaker disposed to connect a direct current source to a load circuit having another direct current source connected thereto, of a calibrating. impedance, means includinga polarized relay ofthe DArsonvaltype having an operating windin connectedin series with the calibrating impedance between the load circuit and the source for preventing closure of the circuit breaker unless the voltage of the source is higher than the voltage of the load circuit, and circuit means including a direct current shunt and auxiliary contact means operable in response to closure of the circuit breaker to connect the operating winding of the polarized relay for energization in accordance with the current through the circuit breaker to provide for opening the circuit breaker if the current flows from the load circuit to the source.

3. A circuit breaker system comprising, a circuit breaker disposed to connect a load to a direct current source, load measuring means for testin the characteristics of the load circuit to determine its suitability for connection to the source by the circuit breaker, relay means controlling the connection of the load measuring means to the load circuit, control means controlled by the load measuring means for effecting closure of the circuit breaker, polarized direction responsive means having an operating winding connected in series circuit relation with a control resistor across the circuit breaker for preventing operation of the control means unless the source voltage is higher than the load voltage, and circuit means including contact means operated in response to closure of the circuit breaker for connecting said operating winding for energization in accordance with the current through the circuit breaker for eifecting operation of the control means to open the circuit breaker if the current flows from the load circuit to the source.

4. In a circuit breaker control system, a circuit breaker disposed to connect a load circuit to a source of direct current power, control means operable to effect opening and closure of the circuit breaker, a polarized relay of the D'Arsonval type having one operating winding energized from the source and an additional operating windin energizable in different directions for completing different control circuits, circuit means' voltage, a direct current shunt connected in series relation with the circuit breaker, and control means including an auxiliary contact member responsive to closure of the circuit breaker to connect the additional operating winding across the shunt for energization in accordance with the current through the circuit breaker for completing the other control circuit to effect opening of the circuit breaker when the current through the circuit breaker flows from the load circuit to the source.

5. An automatic reclosing system for a circuit breaker disposed to connect adjacent direct current circuits comprising, means responsive to excessive current to open the circuit breaker, load measuring means effective upon opening of the circuit breaker to determine Whether the voltage of one of the circuits relative to the other is sufficiently high to permit closing the circuit breaker, control means energizable under the control of the load measuring means to effect closure of the circuit breaker, directional means responsive to the polarity of the potential difference between the circuits to prevent energization of the control means unless the voltage of the other of the circuits is higher than that of said one circuit, and means operable in conjunction with the circuit breaker to reconnect the directional means for operation in accordance with the direction of current flow between the load circuit and source so as to effect deenergization of the control means to open the circuit breaker when the current flows from the load circuit to the source.

6. An automatic reclosing circuit breaker system comprising, a circuit breaker disposed to connect adjacent sections of a direct current feeder between a direct current generator and a. load circuit, means to trip the circuit breaker in response to excess current, load measuring means to determine characteristics of the load circuit, control means operable under the control of the load measuring means to eiTect closure or the circuit breaker, polarized directional responsive means connected between the feeder sections for operation in response to the direction of the voltage differential therebetween to prevent operation of the control means unless the voltage of one section is higher than that of the other, and auxiliary contact means operated by the circuit breaker to connect the directional responsive means to determine the direction of current flow,

between the sections and effect opening of the circuit breaker when the current flows from the other section to said one.

WILLIAM R. TALIAFERRO.

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