US2981869A - Relay control circuit - Google Patents

Description

April 5, 1961 J. E. BALM 2,981,869

RELAY CONTROL CIRCUIT Filed May 8, 1958 INVENTOR.

JOHN E. BALINT ATTORNEY of the various relays.

United States Patent RELAY CONTROL CIRCUIT John E. Balint, Eugene, 0reg., assignor to Controls &

Communications Company, Eugene, Oreg., a corporation of Oregon Filed May 8, 1958, Ser. No. 733,993

4 Claims. (Cl. 317-137) This invention relates to relay control systems and, more particularly, to a circuit for selective operation of oneor more of a plurality of relays and automatic cancellation of all previously selected relays.

In various industrial applications where apparatus is controlled by actuation of relays, it is essential that one selected relay be placed in operation and, at the same cuit application which heretofore required the use of special relays with additional contact elements.

In its broader aspect, the invention provides a circuit which enables the momentary actuation of an electromag ,netic device,such as a relay, regardless of the duration of the actuatingimpulse and permits the cancellation of any or all electromagnetic devices previously held through normal holding contacts and, at the same time, actuates one or more other electromagnetic devices or relays in atsimilar holding manner.

Other objects and features willbe apparent from the .following description of the invention, pointed out in particularity in the appended claims and taken in connection with the drawing in which the figure shows a schematic circuit of the relay control system.

, "Referring to the drawing, the relaysA and N represent a bank of relaysof any number required for a particular system. Each relay in this bank is associated with an operatingswit'ch Sa through Sn. The energizing circuit for the relay A need only be described in detail inasmuch as the circuits of all other relays in the'bank are identical bearing pi'imary indices. a

Power is furnished from lines 1 and 2 which represent any suitable voltage source for energizing the windings For practical purposes this line is usually the available A.C. power. Terminal 3 of the winding of the relay A connects directly to the line 2. The latter may be regarded as the common or ground return of the system. The terminal 5 of the winding connects by means of the conductor 6 to the terminal 7 of the switch Sa.

. The relay A has two pairs of normally open contacts 8 and 9 of which the former is the holding contact and the latter the working or utilization circuit contact. Since the invention is not concerned with the particular appara tus or instrumentality controlled by the relays but rather with the control of the relays, the contacts 9 and 9 show no electrical connection. It will-be obvious that these may beused to close or open any desired circuit, depending upon the arrangement of the contacts and as many circuits as there are contact pairs.

The contacts 8 are the holding contacts and therefore land will Ibefdenotedby the same reference characters are connected on the one side to terminal 5 and on the other side to the line 1 in series with the normally closed contacts 4 of the relay R. The holding contacts of each of the relays A through N in the bank are similarly connected to their respective terminal 5' of the winding and to the contacts 4 of the relay R. Consequently, as will be seen in connection with the description of the operation of the system, the contacts 4, when opened, disconnect all holding contacts 8, 8, etc. from the line 1, thereby releasing all relays held in the bank.

The switches Sa through Sn are of the double-pole, single-throw type, preferably in the form of push buttons or other self-release construction. Each of these switches controls two distinct circuits from the lines land 2. The first circuit of the switch Sa between contacts 11 and 12 applies current directly to the winding-of therelay S, which is termed the supervisory relay of the control system, and also to the winding of the relay R, termed the release relay, through normally closed contacts 14 of the relay S. The other terminal of both windings of the relays S and R respectively, connect to the line 2.

The second circuit of the switch Sa between contacts 7 and 10 supplies the winding of'the relay A. This ties in with the first circuit between contacts 11 and 12 over the normally open contacts 13 of the relay S.

The contact 11' of the switch Sn connects to the line 1 and contact 12 connects by means of the lead 16 to the contact 12 of the switch Sa. Any number of switches between Sa and Sn serving additional relays in the bank wouldbe similarly connected. In the same way the input side of the second circuit served by the contacts 13 of the relay S connects from the junction point 17 to the contact 10 and utilizing the bus 18 to the contact 10' of the switch Sn, etc. 7

Referring to the operation of the system, when any one of the switchs Sa through Sn is depressed, for example, when Sa is depressed, a current path is established in the first circuit between contacts 11 and 12 energizing the winding of the supervisory relay S. At the same time, a current path is also established to the winding of the relay R through the normally closed contacts 14 of the relay S. While current to the relay R is immediately disconnected upon pickup of the relay S which opens contacts 14, suflicient time elapses for the momentary actuation of the relay R, thus momentarily opening and reclosing the normally closed contacts 4."

When the relay S is actuated, contacts 13 close, completing the second circuitbetween contacts 7 and 10 of the switch Sa held down by the operator. Current may now flow to the winding of therelay A closing contacts 8 and 9. When the switch Sa is released, the relay S drops out, the current being disconnected between contacts 11 and 12. However, the selected relay A remains closed inasmuch as the holding contacts 8 complete the I circuit to the line 1 through the closed contacts 4 of the I latter receives out a momentary impulse for the interval during which the contacts 14 are closed; however, the resultant momentary opening of the contacts 4 sufiices to disconnect the holding current of the relay A which will drop out opening the holding contacts 8 and the utilization circuit contacts 9. While Sn is depressed the winding of the relay N becomes energized through closed contacts 13 of the relay S and closed contacts 7' and 10' of the switch Sn. Since the relay'R is new again deenergized, reclosed contacts 4 complete the circuit for the holding contacts 8' of the relay N. The latter thus remains closed after release of the switch Sn. The utilization circuit connected to the contacts 9' is closed and will remain closed until another of the switches Sa through Sn is actuated.

In practice it has proved that a slight delay in the closing of the relay R is desirable to assure that the contacts 4 remain open a sufiicient time to effectuate the dropout of the previously held holding contacts.

For this purpose the relay R may be so chosen as to have operational characteristics which give it a delay in dropout; however, by inserting a capacitance 20 in shunt with the winding of the relay R, theresponse time of the relay may be extended. A delay time of .0015 see. is usually sufiicient for all practical purposes. It has been found that manual operation of the switches requires more than .0015 sec. for even the most skillful operator.

If it is desired to operate several relays, appropriate switches controlling the selected relays may be simultaneously depressed and such relays will remain closed by their holding contacts. .All of these relays will drop out upon later actuation of one or more of the switches.

I claim:

1. In a relay control system for closing any one of a plurality of relays and simultaneously releasing all previously closed relays, a current supply line, a bank of relays, each relay in said bank having holding contacts and contacts for controlling desired circuits, a switch for each relay having contact elements adapted to close, while actuated, simultaneously two distinct circuits supplied from said line, the second of said circuits supplying current to said relays, a supervisory relay having a pair of normally closed contacts and a pair of normally open contacts, said supervisory relay being energized from the first of said distinct circuits upon actuation of any one of said switches, a release relay having normally closed contacts in series between said supply line and all holding contacts of said bank of relays, the winding of said release relay beingconnected to said first circuit and in series with said normally closed contacts of said supervisory relay, said normally open contacts being in series with said second circuit.

2. In a relay control system for closing any one of a plurality of relays and simultaneously releasing all previously closed relays, a current supply line, a bank of relays, each relay in said bank having holding contacts and contacts for controlling desired circuits, a switch for each relay having contact elements adapted to close, while actuated, simultaneously two distinct circuits supplied from said line, the second of said circuits supplying current to said relays, a supervisory relay having a pair of normally closed contacts andv a pair of normally open .contacts, said supervisory relay being energized from the first of said distinct circuits upon actuation of any one release relay being connected to said first circuit and in series with said normally closed contacts of said supervisory relay, said normally open contacts of said supervisory relay being in series with said second distinct circuit.

3. In a relay control system for closing any one of a plurality of relays and simultaneously releasing all previously closed relays, a current supply line, a bank of relays, each relay in said bank having holding contacts and contacts for controlling desired circuits, a switch for each relay having contact elements adapted to close, while actuated, simultaneously two distinct circuits supplied from said line, the second of said circuits supplying current to said relays, a supervisory relay having a pair of normally closed contacts and a pair of normally open contacts, said supervisory relay being energized from the first of said distinct circuits upon actuation of any one of said switches, a release relay having normally closed contacts in series between said supply line and all holding contacts of said bank of relays, the winding of said release relay being connected to said first circuit and in series with said normally closed contacts of said supervisory relay, said normally open contacts of said supervisory relay being in series with said second distinct circuit, said release relay having operational characteristics effecting a predetermined delay in dropout time.

4. In a relay control system for closing any one of a plurality of relays and simultaneously releasing all previously closed relays, a current supply line, -a bank of relays, each relay in said bank having holding contacts and contacts for controlling desired circuits, a switch for each relay having contact elements adapted to close, while actuated, simultaneously two distinct circuits supplied from said line, the second of said circuits supplying current to said relays, a supervisory relay havinga pair of normally closed contacts and a pair of normally open contacts, said supervisory relay being energized from the first of said distinct circuits upon actuation of any one of said switches, a release relay having normally closed contacts in series between said supply line and all holding contacts of said bank of relays, the winding of said release relay being connected to said first circuit and in series with said normally closed contacts of said supervisory relay, said normally open contacts of said supervisory relay being in series with said second distinct circuit, and.a capacitor in shunt with the winding of said supervisory relay for extending the dropout time thereof.

References Cited in the file of this patent UNITED STATES PATENTS

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