US1966189A

US1966189A - Protective relay system

Info

Publication number: US1966189A
Application number: US599697A
Authority: US
Inventors: Roy M Smith
Original assignee: Westinghouse Electric and Manufacturing Co
Current assignee: CBS Corp
Priority date: 1932-03-18
Filing date: 1932-03-18
Publication date: 1934-07-10
Anticipated expiration: 1951-07-10

Description

R. M. SMITH PROTECTIVE RELAY SYSTEM Filed March 18, 1932 July 10, 1934.

iNvENToR Roy M. Smz'/I Bu AT NEY WITNESSES:

UNITED STATES PATENT OFFICE PROTECTIVE RELAY SYSTEM Roy M. Smith, North Arlington, N. J., assigner to Westinghouse Electric 8.av Manufacturing .Company, a corporation of Pennsylvania Application March 18, 1932, Serial No. 599,697

8 Claims. (Cl. V75-294) My invention relates to relays and has par- A moving contact 14 is secured to the spindle ticular relation to relays in which a potential 13 and is arranged to bridge a pair of stationary coil is employed. While not limited thereto, my contact members 15 when the disc is rotated in invention is particularly applicable to protective one direction. A stop 17 is mounted in a posil relays for use in operating circuit breakers in tion to be engaged by the arm 14 to limit the 60 response to predetermined electrical conditions rotation of the disc and spindle in the opposite occurring in an alternating-current system. direction. n Y

It is an object of my invention to provide a Amagnetic vane armature is pivoted, at one relaywhich is responsive to predetermined voltend, to a bracket 6 secured to one side of the age and current conditions, or to predetermined core 1. 'I'he free end of the armature 5 is posi- 65 power conditions, in an alternating-current cirtioned to engage a contact member '7,secured to cuit and in which the sensitiveness of the relay the core 1, or a Contact member 8, ailixed to a is automatically increased when the voltage of bracket 9. The bracket 9 is secured to the core such circuit falls below a predetermined value. l, in any suitable manner, by means of a screw 16 Another object of my invention is to provide a l0 or other securing means. A coil spring 11 is 70. relay in which the entire potential coil is efecprovided for biasing the armature 5 to the positively energized during `normal voltage conditions tion in which it engages the contact member l8. in an alternating-current circuit but in which 1 Under normal conditions, when the potential a part only of the potential coil is rendered eifeccoil 4 is fully energized, the armature 5 is held tive when the voltage of the circuit falls below a in engagement with the contact member 'I against 75 predetermined value. the bias of the spring 11, by the magnetic flux Another object of the present invention is to in the main pole of core member 1. When the provide a protective relay of the induction type voltage applied to the potential coil 4 falls below having means incorporated therein for renderaA predetermined value, the decreased magnetic ,25 ing the relay inversely sensitive to the energizaux produced by the coil in the main pole is in- 80 tion thereof. y suflicient to maintainrthe armature 5 in engage- Other. objects of my invention will become eviment with the contact member 7. The spring' 11 dent from the following detailed description then causes the armature 5 to rotate about its taken in conjunction with the accompanying pivot into engagement with the contact member 8.

3.0 drawing, in which The contact member 7 is connected to one ter- 85 Figure 1 is a schematic illustration in front minal of the potential coil 4, by means of a conelevation of a protective relay embodying my ductor 18, so that voltage is applied to the entire invention. potential coil when the armature 5 is in engage- Fig. 2 is a side view of the relay shown in ment with. this contact member. The contact I Sii Fig. 1, and member 8 is connected to an intermediate tap 90 Fig. 3 is a diagrammatic view of a protective on the potential coil 4, by means of a conductor system utilizing my invention. 19. With such arrangement, only a portion of Referring toFigs. l and 2 of the drawing, an the potential coil has voltage applied thereto when induction-disc type relay is illustrated as comthe armature is in engagement with the termi- `r40 prising a magnetic core 1 having two depending nal 8. n 95 pole portions upon which are mounted current The magnitude and direction of torque acting coils 2 and 3, and having a third or main pole on the disc 12 depends upon the magnitude and portion uponv which is mounted a voltage coil 4. direction of power flowing in the alternating cur- A non-magnetic disc 12, secured to a rotatable rent circuit to which the relay is adapted to be .'45 shaft or spindle 13, is positioned for rotation in connected. A decrease of voltage of the circuit 100 the air gap between the cores of the current and necessitates a correspondingly higher value of potentialcoils 2, 3 andr 4, respectively, in a usual current in the circuit to operate the relay. Howmanner. The current coils 2 and 3 are conever,'if the voltage decreases below the predeternected in series and, when energized, cooperate mined value at which the armature 5 is designed with the energized voltage coil 4 to produce a to release, the armature disengages the contact 105 rotating torque acting on the disc armature 12. member '7 and moves into engagement with the The magnitude yand direction of the torque is contact member 8, thereby establishing a voltage determined by the vresultant fluxes produced by connection through part only of the turns of pothe energized coils 2, 3 and 4 `acting on the disc tential coil 4. Because of the greatly reduced imf `5,5 armature 12. e pedance of the circuit including the potential coil 4, the uX produced by the latter coil increases, thereby reducing the value of current necessary to operate the relay.

Referring more particularly to Fig. 3, I have illustrated one application of my invention for the protection of a power circuit. Conductors L1 and L2 represent a suitable power circuit to which are connected the primary windings of a current transformer 20 and a potential transformer 21. The current coils 2 and 3 of the relay are connected to the secondary winding of the current transformer 2O by means of

conductors

22 and 23 and the potential coil 4 is connected to the secondary winding of the potential transformer 21, by means of

conductors

24 and 25. The conductor 24, however, is connected to the armature 5 and is adapted to engage the contact members 7 or 8, depending on the voltage applied to the potential coil 4.

The stationary contact members 15 are connected in a circuit which includes a suitable source of energy, Such as a battery 26, and a trip coil 27 of a circuit breaker 31 for opening the power circuit. For simplicity I have illustrated a circuit breaker of the manually reclosed type; however it will be understood that my invention may be practiced with any usual type of manually or automatically reclosed breaker and, of course, may be practiced in more elaborate protective systems than the one illustrated.

The operation of the scheme shown in Fig. 3 is as follows: Assuming the circuit breaker to be closed and that power is flowing in the proper direction through conductors L1 and L2, a current proportional to the main current flows through the current coils 2 and 3, and a voltage propontional to the main voltage is impressed upon the entire potential coil 4. The magnetic ux pro duced by the potential coil 4 maintains the armature 5 in engagement with the contact member 7 as long as the voltage between the main conductors L1 and L2 remains normal. The rotating eld produced jointly by the current and potential coils rotates the disc 12 and spindle 13 in the usual manner until the moving contact 14 strikes the stop 17. The relay then remains in this position as long as normal conditions exist in the power circuit.

Assuming, however, that some abnormal condition occurs in the power circuit which causes the voltage applied to the potential coil 4, to fall below the predetermined value at which the armature 5 is designed to operate, then the magnetic ux produced by the potential coil decreases, so that the spring 11 causes the armature 5 to rotate about its pivot into engagement with the contact member 8.

This reduces the impedance of the circuit including the potential coil 4, in the manner pref kviously described, and causes the ux produced by the latter coil to increase. If now the direction of power ow in the main conductors L1 and L2 reverses, the direction of torque applied to the disc 12 reverses, and the moving contact 14 moves into engagement with the contact members 15. Because of the increased flux produced by coil 4, a minimum of reverse current is required for the performance or the latter operation. Upon the engagement of the moving contact 14 with the stationary contacts 15, a circuit is completed for the trip coil 27 of the circuit breaker. The circuit breaker 31 is thereupon actuated to its open position and the circuit breaker may be manually reclosed in the' usual manner when the fault or abnormal power con# dition on conductors L1 and L2 is remedied.

It is, therefore, apparent to those skilled inthe art that I have provided a relay that is sensitive to predetermined voltage and current, or to predetermined pow er conditions, and in which the sensitiveness of the relay is automatically in"-r creased whenl the voltage of the power system falls below a predetermined denite value. The relay is, furthermore, sensitively responsive to reversal of power with moderate Values of reverse current in the power circuit under a wide range of values of line voltage.

Although I have shown one specic embodiment of my invention I do not desire to be limited thereto as various other modications may be made without departing from the spirit and scope of the appended claims.

I claim as my invention:

l. In protective apparatus for an electric circuit, a circuit breaker for controlling said circuit, control means for said circuit breaker including a relay having coil means, energizing means for said relay including electrical connections for normally energizing a predetermined number of turns of said coil means in accordance with an electrical condition of said circuit, and means responsive to a predetermined reduction of voltage in said circuit for modifying said connections to cause a different predetermined number of turns of saidcoil means to be energized in accordance with said electrical condition, to thereby alter the sensitiveness of said relay under low voltage conditions of said circuit.

2. In protective apparatus for an electric circuit, a circuit breaker for controlling said circuit, control moans for said circuit breaker including a relay having a'magnetic core, a coil in inductive relationshipA to said core and a main armature responsive to a magnetic condition of said core, energizing means for said relay including electrical connections between said circuit and said coil for normally maintaining a predetermined ratio between an electrical condition of said circuit and a-magnetomotive force applied to said core, and means including an auxiliary armature responsive to a predetermined abnormal flux condition of said core for modifying said connections to establisha different predetermined ratio between said electrical condition of said circuit and said magnetomotive force.

3. In a protective system, an electrical circuit, a circuit breaker for interrupting said circuit, means for actuating said circuit breaker upon the occurrence of predetermined electrical conditions in said circuit including a relay having a potential coil and a potential circuit for applying a voltage to said coil, and means associated with said coil responsive to a predetermined decrease of voltage of said circuit for excluding the entire potential coil from said potential circuit and inserting a portion only of said coil insad potential circuit to increase the sensirzveness o1' said relay.`

4. In a relay, a magnetic structure having a plurality of spaced pole members defining an air gap, a plurality of coils mounted upon said pole members, a disc armature pivotally mounted for rotation in said air gap, contact members controlled by said disc armature, energizing connections for said coils including a circuit of predetermined impedance phase angle for energizing one of said coils, an auxiliary armature mounted to move in response to variations of flux in one cf said pole members, auxiliary contact members controlled by irs said auxiliary armature, and means including said auxiliary contact members for altering the electiveness of said one of said coils while maintaining said imped'ance phase angle substantially unchanged.

5. In protective apparatus for an alternating current circuit, a circuit breaker for controlling said circuit, control means for said circuit breaker including a relay having a magnetic core, a firstr coil in inductive relationship to said core, a second coil and an element responsive to a vector product of magnetic conditions produced by said coils, energizing means for said relay including electrical connections for normally maintaining a predetermined ratio and a predetermined phase relationship between an electrical condition of said circuit and a magnetic condition produced by said first coil, and means responsive to a predetermined abnormal ilux condition of said core for modifying said connections to establish a different predetermined ratio and to maintain substantially the same predetermined phase relationship between said electrical condition and said magnetic condition, to thereby alter the sensitiveness but not the phase angle characteristics of said relay during an abnormal condition of said circuit.

6. In a relay, a magnetic structure having a plurality of spaced pole members defining an air gap, current coils and a potential coll mounted upon said pole members, a disc armature pivotally mounted for rotation in said air gap, contact members controlled by said disc armature, an auxiliary armature mounted to move in response to variations of voltage impressed upon said potential coil, and means including contact members controlled by said auxiliary armature for causing a predetermined voltage to be impressed upon the entire potential coil or a portion only of said coil depending upon the variation of the impressed voltage.

7. In a relay, a magnetic structure having a. plurality of spaced pole members defining' an gap, current coils and a potential coil mounted upon said pole members for operating said relay when current and voltage are applied to the respective coils, a disc armature pivotally' mounted forr rotation in said air gap', contact members controlled by said disc armature, anv auxiliary armature mounted to move in response to variations off flux produced by said potential coil, and means including contact members controlled by said auxiliary armature for causing said voltagel to be impressed upon the entire potential coil when saidv voltage is above a predetermined value, or to be applied to a portion only of said coil when said voltage is below a predetermined value, to thereby reduce the value of current necessary to operate said relay during an undervoltage condition.

8. In a. protective system, an electrical circuit, a circuit breaker for interrupting said circuit, means for actuating said circuit breaker upon the occurrence of a predetermined electrical condition in said circuit including a relay comprising a magnetic structure having a plurality of spaced pole members defining an air gap, current coils and a potential coil mounted upon said pole members, a disc armature pivotally mounted for rotation in said air gap, contact members controlled by said disc armature, a magnetic armature mounted to move in response to variations of voltage impressed upon said potential coil, and means including contact members controlled by said magnetic armature for causing a predetermined voltage to be impressed upon the entire potential coil or a portion only of said coil to increase the sensitiveness of said relay.

ROY M. SMITH.