US2434948A - Impulse actuated electromagnetic relay with time delay - Google Patents

Description

' um. 27, 1948 "H. GQMILLER 2,434,948

' IMPULSE ACTUAL 1D ELECTROMAGNETIC RELAY WITH TIME DELAY J Filed Jan. 27, 1944 Puss Sauna-'34 r u uwtzvroa C v HORACE 6. mai

Patented Jan. '27, 1948 IMPULSE AO'I'UATED. ELECTROMAGNETIC RELAY WITH'TIME DELAY Horace G. Miller, Belleville, N. .L, assignor to Federal Telephone and Radio Corporation,

New York. N. Y., a corporation of Delaware Application January 27, 1944, Serial No. 519,927 9 Claims. (01. 175-320) The present invention relates to apparatus oi the type suitable for regulating the operation of electrically controlled circuit breaking devices.

devices being receptive erated at a diflerent source.

It is frequently desirable to provide means for I automatically maintaining an electrically controlled circuit breaking device such as a relay in one of its control positions after the flow of energy through the device has ceased. It is also desirable to cause the device to remain in this control position for the same predetermined period of time following the initial reception of each of the various intervals of energization, without regard, within certain limits, to the duration of the intervals or the time that elapses between them.

It is accordingly the principal object of the present invention to provide a simple and inexpensive circuit arrangement for carrying out the above aims.

It is a further object oi. the invention to provide additional means in an arrangement of the above type that will permit the position of the circuit breaking device to be altered before expiration of the said predetermined period of time and without regard to the status of the automatic maintaining means. 7 It is a still further object of the invention to provide an improved form 01' time-delay system for a circuit breaking device, the period. of delay being determined by the time constant of a resistance-condenser combination.

It is an additional object of the invention to provide a holding circuit for a relay, this circuit being responsive to an initiating input pulse of relatively narrow width, for holding the relay in closed position for an interval of time that is longer in duration than that of the initiating input pulse.

It is a further object of the invention to provide a single time-delay circuit eflective to control the operation of a plurality of circuit-break ing devices receptive'to pulses generated at sepa-- rate source and designed to control separat loads.

It is a still further object of the invention to provide means for deriving pulses of equal width from pulses of unequal width.

Other objects and advantages will be apparent from the following detailed description of pre- Fig. 1 of the drawing accordingly shows two separate control circuits each including a separate circuit-breaking device, these circuits being energized by pulses generated at diiierent sources. A single time-delay circuit is so incorporated with these control circuits as to provide a delay interval for each, this interval being of equal duration to thereby cause all of the control circuits to remain energized for substantially identical periods of time.

Although any number of control circuits may be incorporated with the single time-delay circuit as will later become apparent, only two have been illustrated, and the operation of the invention will be described in connection with but one.

In Fig. 1 is shown three triodes V1, V2 and V3, the grids of which are respectively connected to three pulse sources "A, B and "C." These sources produce pulses of widths t1 t4 and ts, as indicated, which may be equal or unequal. The anodes oi triodes V1, V9 and V; are connected to a ource of power 3 through the coils of three relays I, 5 and 4' respectively. Relays 4 and l are each provided with two pairs of normally open contacts 8, 1 and 6', 1' respectively. Relay 5 is provided with a pair of normally closed contacts 8. In a conventional manner each of these pairs includes a stationary contact and a; movable contact as illustrated.

A resistor R1 is connected between the anode terminal or the coil of relay 4 and normally open contacts 6. Another resistor R3 is connected in a similar manner between the anode terminal of the coil of relay l and normally open contacts 6'. Contacts 6 and 6' are joined as shown ,to normally closed contacts 8. Contacts 8 are in turn connected to one plate of a condenser C, the other plate of the condenser being grounded.

Shunted across condenser C is a further resistor R2. In parallel with C and R: is a manually operable switch S. Normally open contact I and I respectively control the flow of power from sources iii and It to loads ii and H.

The invention will now be described in connection with one of the control circuits shown in Fig. 1. Since the principle or operation of each of these circuits is the same, the one including triode V1 has been selected. Obviously, however, the one including triode V3 might as readily have been chosen. In the following description, switch S i assumed to be open.

When a pulse from source A of duration t1 is applied to the grid of triode V1 (both V1 and V2 being biased to or beyond cut-off) the tube becomes conductive and current will flow through the coil of relay 4. Contacts 6 and 1 will now close.

As soon as contacts 6 close, a circuit will be to pulses of energy gen-- established through source or power 8. coil 4, resistor R1. normally closed contacts 8 and to ground through condenser C. This will charge condenser C for a period which will be designated as is. During this period ta that C is chi-13 118 through R1, current flowing through the coil of relay 4 maintains contacts 6 and 1 closed.

When C becomes fully charged (the time constant t: required for such charging being dependent on the values oi. R1 and C in a manner known in the art), the current flow through the coil of relay 4 will cease, and contacts 6 and 1 will open. It will be noted that the energy represented by the pulse from source A may or may not be applied to the grid of triode V1 during the entire period lie that C is charging, it being immaterial whether the initiating energy continues or not after such time as the relay 4 is locked-in by establishment of a circuit through R1 as above described. However, the interval t1 preferably should not exceed the time constant 1.: of RiC, the values of R1 and C being selected with this condition in mind.

Resistor R2 is chosen to be of a considerably higher value than R1 so as not to aiiect to any appreciable degree the charging of C through R1 as previously described. The purpose 01' R2 is to discharge condenser C upon breaking of the circuit through resistor R1. and to thereby restore the system in preparation for another cycle of operation. If the time required for C to completely discharge through R: after contacts 6 open be designated as ts, then it will be seen that the sum of t: and is can equal but not exceed the time between successive pulses from source A.

The loads H and H respectively controlled by contacts I and I may be of any standard type, such as for example stepping relays. Also the contacts 1 and I may, if desired, control the operation of pulse generating devices for producing pulses having a width corresponding to the intervals during which contacts i and I are closed. Many other control applications will also be readily apparent to those skilled in the art.

The above cycle of operation has assumed that switch S is open (or that the system is selfclearing), and that triode V2 is non-conductive. If, however, switch S be closed (making the system remote-clearing"), elements C and R2 will be short-circuited, and a closing of contacts 6 and l as above described would normally result in the contacts remaining in such position indefinitely.

However, if a pulse from source B of some duration such at it is now applied to the grid of triode V2, the latter becomes conductive to energize the coil of relay 5. Contacts 8 now open, breaking the circuit from the coil of relay 4 through R1 to ground by way of switch S. Contacts 6 and I now open due to the deenergization of the coil. It will be seen that a pulse from source B may be received by triode V2 at any time subsequent to the arrival of a pulse from source A on the grid of triode V1. It will also be seen that the remote-clearing action of the system dominates the self-clearing or automatic action. This is true because opening of contacts 8 as a result of the energization of relay 5 by the pulse from source B clears the holding circuit and opens contacts 6 and I regardless of whether switch S is open or closed. Also the duration t; of the pulse from source B may be immaterial, if the only requirement is that the triode V2 be conductive for a sufficient time to permit contacts 8 to open. However it will be clear that t4 must not be of such length as to interfere with the chargin of condenser C upon the reception of the next pulse by triode V1 from source "A."

It will be obvious that the separate control circuit including triode V: and relay 4' operates in a manner similar to that described above for the triode V1 and relay 4. Resistor Rs may have a value such that the time constant RcC equals R1C, or else it may have any other value desired so that contacts 'I' will remain closed for longer or shorter intervals than contacts 1.

However, it is emphasized that, in order for all of the intervals during which contacts 1' are closed to be or equal duration. and in order for all of the intervals during which contacts I be closed to be also of equal duration, the pulses from sources "A and 0'' must not arrive simultaneously, and furthermore successive pulses, whether from the same or from diflerent sources, must be spaced apart a suiiicient distance to allow for theiull discharging of condenser C.

It will be obvious that if desired additional circuits including relays 4' and triodes V: may be added in parallel relation with the one shown.

In Fig. 2 is illustrated a circuit incorporating a different type of condenser discharging means from that shown in Fig. 1. In this arrangement an additional stationary contact 6a is associated with contacts 6, so that condenser C is normally short-circuited when relay 4 is deenergized. When current flows through the coil of relay 4 as a result of the reception of a pulse from source A, condenser C will charge in the manner previously described. When the how oi current through the relay coil ceases due to the attaining by C of its full charge through R1, contacts 6 will open. This opening of contacts 8 will short-circuit condenser C through contact Ba thereby discharging the condenser to ground. Thus the system is conditioned for another cycle of operation. It will be noted that in the arrangement as shown in Fig. 2 the separate discharging resistor R2 of Fig. 1 is not required. However, this arrangement of Fig. 2 is suitable for only one relay 4.

From the above it will be seen that the present disclosure includes numerous features. Means are provided whereby a circuit breaking device may be held in closed position for a predetermined period of time that exceeds in duration that of any of the initiating pulses. This same predetermined holding period is maintained even though the width of succeeding received pulses may vary to a considerable degree. If it is desired to maintain the closed position of the device until such time as a clearing pulse is received, this may be accomplished through the act of closing a selector switch as shown in Fig. 1. In addition the system provides means whereby means such as a clearing pulse will be effective to deenergize the system regardless of whether the selector switch has been closed or not, and.

also without regard to the status at that time of the automatic clearing means.

While I have described above the principles of my invention in connection with specific circuit arrangements, it is to be clearly understood that this description is made only by way of example, and not as a limitation on the scope of my invention as set forth in the objects 0! my invention and in the accompanying claims.

I claim:

1. In an electrical circuit including an energy source, an electro-responsive mechanism anda source of power, the combination of a normally inoperative control element in circuit relation with said source of power and said electro-responsive mechanism, means responsive to the initial reception of energy from said source, said energy being of a certain duration to render said element operative to energize said electro-responsive mechanism, a resistance-condenser combination having a time constant greater than the duration of said reception of energy said combination being serially connected across said source, and means under control of said resistance-condenser combination, whereby said mechanism is maintained energized for a predetermined time over a circuit independent of said control element.

2. An electrical circuit. according to claim 1 in which the electro-responsive mechanism is energized by current flow to charge said condenser.

3. An electrical circuit according to claim 1, further comprising means for discharging the condenser of said resistance-condenser combination after deenergization of said electro-responsive mechanism following the energization thereof, and prior to the next succeeding reception of energy by said normally inoperative control element, said discharging means being connected in parallel with said condenser.

4. In an electrical circuit including a normally open relay and a source of power, a normally nonconductive element in series with said source of power and with the coil of said relay, a, first source of pulse energy, means responsive to the initial reception of a pulse of energy of a certain duration from said first source by said element to render said element conductive and thereby close said relay, a time-delay circuit connected in operative relation with the relay coil over a path independent of the normally nonconductive element and having a predetermined delay interval greater than the duration of the pulse of energy received by said element, and means responsive to the closing 01' said relay to initiate the operation of said time-delay circuit,

whereby said relay will open at the expiration of said delay interval.

5. An electrical circuit according to claim 4, further comprising a second normally non-conductive element, and means responsive to the reception of energy by said second element during the said time-delay interval to return said relay to open position irrespective of the electrical status or the said time-delay circuit at the time energy is received by said second element.

6. In anelectrical. circuit including a pair of relays and a source of current. the combination of a pair of normally non-conductive elements.

- two series circuits, each circuit including the source of current, the coil of one of the said relays, and one of the non-conductive elements,

' respectively, means for rendering one of said elesive mechanism a source of successive pulses of a certain duration t1 for controlling the closing of said eectro-responsive mechanism, a condenser, means responsive to the initial reception of one of said pulses and connected to said electroresponsive mechanism to initiate the charging of said condenser, means whereby the latter maintains the said mechanism closed during a certain charginginterval t2, and a circuit rendered operative by the opening of said mechanism following the closing thereof for discharging said condenser during a third interval t3, wherein t2 tn and the sum of is and ts is equal to'or less than the elap ed time between the beginnings of suecessive pulses.

8. In combination, a source or current, an elecrically-controlled normally open circuitbreaking device connected to said current source, a circuit including a normally non-conductive element connected to said device, an energy source for energizing said element, means responsive to the initial reception of said energy, said energy being of a certain duration, to close said circuit-breaking device, a time-delay circuit serially connected with said current source having a predetermined delay interval. means re sponsive to the initial reception or energy by said element to initiate the energization oisaid timede'ay circuit, said predetermined delay interval exceeding in duration the time during which en ergy is received by said element, whereby said time delay circuit will open at the expiration oi said predetermined delay interval.

9. In an electrical circuit including a plurality of electro-responsive mechanisms, a source of power, a source of energy, a plurality oi normally non-conductive,elements, each of said normally non-conductive elements being respectively connected in series with one or said electro-respom sive mechanisms and said source of power, means responsive to the initial reception oi said energy by one of said elements/to render said clement conductive and thereby energize the electro-re sponsive mechanism in series therewith said energy being oi a certain duration. a plurality oi resistance condenser and deriving charging cur= rent from said power source combinations having a common condenser. the resistances of each of said combinations being respectively associated with respective non-conductive elements. each of said resistance-condenser combinations having a time constant greater than the dim. tion of reception of energy by the normally nonconductive element associated therewith, and means responsive to the energization of one or said electro-responsive mechanisms to initiate the charging of said condenser whereby said last mentioned electro-responsive mechanism will be de-energized when said condenser is fully charged.

HORACE G. MILLER.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2.165.048 Gilliksen July 4, 1939 2,032,514 Swart Mar. 8, 1936 2,147,468 Stoddard ..'Feb. 14. 1939 2,221,569 Berkey et a1. Nov. 12. 1920 2,282,182 Gilliksen May 5. 1942 1,909,471 Kelly May 16, 1933 2,008,413 Dawson July 16, 1935

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