US1793478A - Relay - Google Patents

Description

Feb. 24, 1931. s. L. GOLDSBOROUGH RELAY Filed May 25, 1925 lNVENTOR 5/5067 L 6o/asomzyf2.

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/ l ATTORNEY shall be controlled by a plurality of Wind Patented Feb. 24, 1931 UNITED STATES PATENT, OFFICE SHIRLEY L. GOLDSBOBOUGH, OF PITTSBURGH, PENNSYLVANIA, ASSIGNOB 'I O WEST- INGHOUSE ELECTRIC & MANUFACTURING COMPANY, A. CORPORATION OF PENN- SYLVANIA Application filer! Kay 25,

My invention relates to electromagnetic relays and particularly to protective relays for distribution systems.

' One object of my invention is to provide a relay that shall have increased sensitivity when abnormal conditions obtain.

Another object of my invention is to provide a, relay having contact members that ings and that shall have means for positively preventing closure of the contact members except when one of said windings is abnormally energized.

Another object of my invention is to pro vide a relay that shall have a current actuating winding, a voltage restraining winding and voltage-responsive means for preventing the operation of the relay until the energization of said restraining Winding is reduced to a relatively low value.

' In more general terms, the object of my invention is to'provide a relay with an auxiliary electromagnetic device for precluding the operation of the relay during normal circuit conditions.

In many applications of protective relays for distribution systems, the desired adjustmentof the relay is affected by the connected generator capacity, which may vary considerably at different times. The adjustment of an over-current relay, for instance, must be changed if the generator capacity is so reduced that a short-circuit draws less or only slightly greater current than the normal load current at times of peak load. In ac cordance with my invention, the necessity for such re-adjustment is obviated by the use of a voltage-responsive device that renders the relay inoperative until the occurrence of the drop in voltage that accompanies a short-circuit. The relay may therefore be adjusted to operate upon a short-circuit which draws a relatively small current and will not operate upon a normal load current in excess of this value. The voltage-responsive device may either control a winding of the relay or hold the movable element of the relay stationary under normal circuit conditions.

Referring to the accompanying drawings,

"RELAY 1825. jerial No. 32,545.

- Fi 1 is a diagrammatic View of a relay cmbodying the invention, and

Fig. 2 is a similar view of a modified form of relay embodying the invention.

Referring to Fig. 1,'the relay comprises a magnetizable core member 1 having a winding 2 thereon energized from a circuit 3 through the instrumentality of a current transformer 4. A second winding 5 of the relay is inductively related tothe Winding 2 and is connected to the windings 6 and 7 upon the upper pole pieces of the core member 1. The circuit of the windings 6 and 7 is normally interrupted at the contacts of a potential relay 8 that is energized through a voltage transformer 9 from the circuit 3. The relay also comprises an armature member 10 that is actuated by the out-of-phase magnetic fluxes produced by the windings 2, 5, 6 and 7. When the circuit 3 is subjected to a shortcircuit, the armature member 10 actuates a movable contact member 11 to engage a stationary contact member 12 to close an auxiliary circuit 13, which may contain the trip coil of a circuit-interrupter (not shown), or any alarm device.

In order to render the relay sensitive to a short-circuit that draws a current approximately equal to, or only slightly in excess of, full-load current, the potential relay 8 is adjusted to maintain the circuit including the windings 6 and 7 open until the voltage in the circuit 3 is reduced a relatively large amount, such as to or 75% of its normal value. Upon the occurrence of a short-circuit, the voltage of the circuit 3 will drop, the potential relay 8 will close its contact members and the armature member 10 will be actuated to close the contacts 11 and 12 even though the current traversing the'circuit 3 is no greater than the normal peak-load current. Under normal conditions, the peakload current will not cause the operation of the relay because the auxiliary potential relay 8 maintains the circuit of the upper pole windings open.

It will thus be seen that I have provided a sensitive relay that will be operated in the case of short-circuits that do not draw an excessive current. However there is no pos sibility of the relay operating upon the normal load current because of the inoperative condition of the up er pole windings. -It will be understood hat the relay 8 will be adjusted to operate at any desired voltage below the normal circuit voltage depending upon the particular conditions met.'- If the regulation of the voltage of the circuit is close and the fluctuations in load/do not cause it to fluctuate more than a known percentage below the normal voltage, the relay may be ad'usted to o crate, u on an reater dro J p p y g I rent winding for e ecting' the rotation of in voltage.

In Fig. 2, I have shown a modification of my invention embodyin a positive latching device for preventing file operation of the relay. The relay comprises a current winding 15 and a voltage winding 16, the relay being of the impedance type described and claimedin the copending application of L. N. Crichton. Serial No. 641,701, filed May 26,

1923. The current and the voltage windings of the relay are connected to the circuit 3 through current and voltage transformers 4 and 9, respectively. The movable element of the relay comprises .a contact arm .17 connected to the armature or core member 18 of the voltage winding and to the armature member 19 of the current winding through a spring 20 and a depending arm 21. When the current traversing the circuit 3 exceeds a predetermined value, the armature member 19 is actuated from its normal position against the restraining force of the spring 22 and; Y

through the spring 20 exerts a graduallyincreasing torque upon the contact arm 17.

The contact arm 17 is locked against move-' ment by the voltage winding 16 for a length of time which depends upon the degree of energization of said winding and consequently upon the potential of the circuit 3.

The armature member 19 is provided with a lug or catch 23 that is normally engaged be limited in scope except as indicated in the appended claims.

claim as my invention:

1. A relay comprising a current winding, I

a voltage restraining winding, a movable contact member jointly controlled by said windings and electromagnetic means associated with said windings to positively prevent the actuation ofsaid contactmember under nor mal voltage conditions.

2. An impedance rela of the induction disc type comprisin a isc member, a cursaid disc member, a voltage-restraining winding, means controlled thereby for co-operatin" with said disc member to control a movable contact member, and electromagnetic means associated with said disc member for positively preventing the movement thereof under normal-voltage conditions.

3. In an induction disc-type relay electri nitude of current in said system.

In testimony whereof, I have hereunto subscribed myaname this 14th da of May, 1925.

' SHI LEY L. GOLDS OR OUGH.

by a flexible latching strip 24 mounted upon the movable core member 25 of an auxiliary electromagnetic device 26. The device 26 is connected across the secondary winding of the potential transformer 9 and is adjusted to latch the armature member 19 in its norcircuit occurs, the relay may be adjusted to operate upon short-circuits that draw a cur-- rent equal to or only slightly greater than the normal peak-load current. By reason of the flexiblecharacter of the latch member 23,

the armature 19 will reset to its latched posi tion under the tension of the spring 22, when the relay is de-energized.

I do not consider that my invention is limited to the precise forms shown and de-- scribed and accordine'lv I do not wish that it

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