US2004768A - Protective system - Google Patents

Description

June 11,1935. Q SAMUELS 2,004,768

PROTECTIVE SYSTEM Filed Oct. 13. 1952 Inventor" Raemon C. Samuel's,

by vie His Attorney.

Patented June 11, 1935 PATENT OFFICE PROTECTIVE SYSTEM Daemon C. Samuels, Philadelphia, Pa., assignor Ito-General Electric Company, a corporation of New York Application October 13, 1932, Serial No. 637,624

Claims.

lllly iu'vention relates to control systems, more particularly to a protective relay arranged to pievent a'contactor repeatedly opening and closingin case its'holding resistorshould be open 5 circuited'and has'ior an object the provision of a simple and reliable system oithis character.

1 "In the operation of automatic substations or other equipment which is to be remotely controlled, it is desirable to prevent the operation oithe circuit contmlling switch in case its holding resistor would become open circuited. Heretotore the result of an open circuit in the holding resistor caused a pumping action of the switch. That'is tosay, the operating circuit of the switch wouldbecompleted, the switch would close, and ymeans of'interlock contacts'the operating circuit would lie-interrupted and 'acircuit would be completed throughthe holding'resistor. But became 1 of the-open circuit in the holding resistor the "contactor would immediately open. This cycle oi operations might continue until the operating coil of the switch burned out.

' in carrying out my invention in one form thereoif'I provlde'con'nections whereby the operation 26' or the circuit controlling switch is dependent upon 'the'completiono! a circuit through the holding resistor. More particularly, I provide a relay with-its operating coil in series with the holding resistor and with its contacts arranged to complete thcope'mting clrcuitto the switch so that the operating circuit cannot be completed upon the failure of the resistor.

l"or a more complete understanding of my invention reference should now be had to the accompanying drawing in which I have illustrated diagrammatically my invention.

Referring now to the drawing, I have shown my invention in one form as applied to a circuit controlling switch lll provided with the usual armature an operating coil l I and normally closed interlock contacts l2. A holding resistor i4 is connected in circuit with the operating coil II. A protective relay i5 has its holding coil I6 connected in series with the holding resistor I4 and the normally closed interlock contacts l2. The contacts i8 of the relay l5 are arranged to short circuit the holding resistor l4.

In explaining the operation of my invention, it will be assumed that the supply lines 20 and 2| are energized from a suitable source of supply (not shown) and that a. control switch 22 has been closed. The energizing circuit for the operating coil I6 of the relay I5 depends upon a circuit including the resistor l4. This circuit may be traced from the supply line 20, control switch 22,'conductor 24, holding resistor l4, operating coil i6, interlock contacts l2, and to the other supply line 2!. The relay l5 immediately closes its contacts II to complete an energizing circuit for the operating coil I I of the circuit controlling switch I 0. This circuit may be traced from the supply line 20, control switch 22, conductors 24 and 26, relay contacts l8, and by conductors 21 and 28, operating coil Ii to the other supply line 2i. The circuit controlling switch I0 is immediately operated to close its contacts 30 and to open the normally closed interlock switch contacts I2. The opening of the contacts l2 interrupts the energizing circuit for the relay l5 which immediately operates to open its contacts, thereby inserting the holding resistor H in series with the operating coil Ii. The holding circuit may be traced from the supply line 20, switch 22, conductor 24, holding resistor I4, conductor 32, operating coil i I and to the other supply line 2|. I

' By means of the contacts 30 a circuit breaker 34 of the latched-in type is arranged to be closed through the cooperation of the relay 35. The

energizing circuit for the relay 35 may be traced from supply line 20, conductor 31, interlock contacts 38 operating with the contactor 34, operating coil 39, relay 35, contacts 30 of the controlling switch l0 and to the other supply line 2|. Consequent to the closing of the relay 35 an energizing circuit for the operating coil 40 in contactor 34 may be traced from the supply line 20, conductor 42, operating coil 40, contacts of the relay 35 and by conductor 43 to the other supply line 2 I.

In order to operate the latched-in contactor 34 to its open position, it is only necessary to open the control switch 22. The result is the deenergization of the operating coil ll of the circuit controlling switch ill. As the contacts 3|] are opened the contacts 45 operated with this switch are closed to complete an energizing circuit for the trip coil 48 of the latched-in contactor. This circuit may be traced from supply line 20, by conductor 48, interlock contacts 49 operated with the contactor 34, trip coil 46, contacts 45 and to the other supply line 2|.

Similarly additional contactors (not shown) may be controlled by adding additional contacts 50, shown by broken lines, to the switch Ill.

It will now be assumed that a failure of the holding resistor l4 has occurred, or, in other words, that the holding resistor is open circuited. If the control switch 22 is now closed an energizing circuit cannot be completed for the operating coil l6 of the relay i5, because the operation of the relay l5 depends upon thecompletion of its energizing circuit through the resistor I4. Consequently, the circuit controlling switch 10 cannot be operated unless the relay I5 is operated to exclude the holding resistor M from the operating circuit to the coil I I.

If it were not for the provision of relay IS, the closing of the control switch 22 during the open circuiting of the resistor l4 would cause the switch I'll to close and to open in rapid succession, since contact l8 would be operated by relay ll instead of by relay [6. would cause damage to the switch l0. Furthermore, the pumping action produced by the opening and closing of the contactor 34 would result in heavy bumps on the line and might result in considerable damage.

While I have shown a particular embodiment of my invention, it will be understood, of course,

that I do not wish to be limited thereto since many modifications maybe made, and I, therefore, contemplate by the appended claims to cover any such 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 combination, a switch provided with an operating coil, a holding resistor, connections for connecting said resistor in series'with said coil thereby to limit the current flow through said coil to a predetermined value, an operating circuit for increasing the energization of said'coil, and means for preventing repeated operation of said switch in case of failure of said resistor comprising a relay having its operating coil connected in series with said resistor, and connections for con necting said relay in said operating circuit so that the completion of-said operating circuit depends upon the operation of said relay.

2. A control system including a switch provided 3. In combination, a circuit controlling switch This pumping action provided with a plurality of contacts one of which is normally closed, an operating coil for said switch, a relay provided with normally open contacts and an operating coil, a current limiting resistor, connections for connecting said resistor in series with said operating coils, connections for connecting said relay contacts across said resistor, I

connections for including Said-.{normalIyl' closed contacts in circuit with said relaybpei'ating coil, and means including said resistor for controlling the energization of said relay operating coil the said means being ineffective upon-failure of said predetermined'voltage exists, to permit said magnet coil to closesaid switch, a normallyclosed interlock switch connected incircuitiwith said relay coil, and means responsive to the closin g of said switch for opening saidinterlocl; switch whereby said relay operates to re-insertsaid re, sistance in series with said magnet coil.

5. The combination with power, supply .circuit, a normally open switch provi'ded with an armature, a magnetcoilfor operatingsaid armav ture to close said switchand a circuit for said coil connected to said supply circuit-of a resist-, ance in series with said coil suflicient when in series with said coil to prevent said magnet coil from closing said switch While apredetermined i voltageexists across said supply circuit, and electroresponsive means connected to said supply circuit in series with said resistance for-short cir-. cuiting said resistance when said predetermined voltage exists and thereby causesaid magnet coil to operate said armature to close said switch, and means responsive to the movement of said arms..- ture in closing said switch for operating said electroresponsive means to re insert saidresistance in series with said magnet coil. Y W 1 RAEMON- C.. SAMUEIS."

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