US2424582A - Electrical signalling system with remote control - Google Patents

Description

July 29, 1947 w. POULIART ELECTRIQCAL'SIGNALLING SYSTEM WITH REMOTE CONTROL 2 Sheets-Sheet 1 Filed Jan. 22, 1943 I N VENTO R WIlL Y 1 01/6/19 ATTORNEY July' 29, 1947. w. POULlART ELECTRICAL SIGNALLINE SYSTEM WITH REMOTE CONTROL Filed Jan. 22, 1943 2 Sheets-Sheet 2 N N M Haw INVENTOR mu y FOUL/HR? v N w w A Patented July 29, 1947 ELECTRICKL SIGNALLING SYSTEM WITH REMOTE CONTROL Willy Pouliart, Antwerp, Belgium, assignor to In-- ternational Standard Electric Corporation, New York, N. 31., .a corporation of Delaware Application ilanuary 22, 1943, Serial No. 473,276 ln t-he Netherlands June .23, 1941 llClaims. 1

This invention relates to new and useful :improvements in electrical signaling systems and particularly in systems for supervising and/or controlling from a central :point the positions (of a plurality of mechanisms'locatedzat one or.more distant points by-means of electrical signals sent over a small number of wires.

Many such signaling "systems are :known in which indications are sent from the outlying point to the'central point, or in which .meansvare provided for actuating mechanical or electrical devices at a distant point by manipulations atqthe central point. These knowneystem operate on one of the following two-principles:

(a) Code systems Each mechanism .at the distant endisprovided with one or more contact sets, each -set corresponding to a definite position or conditionwhich itis desired to indicate. To each contact set is assigned .a predetermined code, consisting of a combination of electrical current impulses. These impulses may consist of the Opening-and closing of a unidirectional direct current circuit, or of trains of impulses of positive .or negative polarity.

The .codesending device may be directly associated with each contact set and may be-individual to each contact set, .thecode beingreleased by ..a so-called -trigger .aotion, when the contacts are actuated. The code-sending device may also be common to a plurality of contact sets, and the commoncodesender controlled by means individual .to each contact set.

The different codes .are received at thecentral point by an appropriate controlling device, which counts the number .of pulses of different characteristics for thepurpose of 'identiiyingeach individual code.

Systems with individual code sending devices must, however, necessarily be provided with..-complicated mechanisms, which .may impairthe reliability of .the operation.

Systems with a common code sender must be specially designed to avoid. interfering reciprocal i action'between different indications. A .further disadvantage-is that during onerevolutionoftthe sender only one code can besent.

(bi Synchronized stepping systems These systemsmakeuse of a rotating mechanism, usually in the form of some type of, selector switch -with a bank of terminalsand a rotating brush member at eachend of the signaling wire.

The arrangement is usually such that .each ..con- 55 or segment.

'2 tact set, the position of which has to be indicated, is connected to a definite bank terminal at thedistant point, whereas the relevant signal isconnected'to the corresponding bank terminal at the central point.

The two rotating mechanisms are arranged to rotate or step in synchronism, by means-of any one of a plurality of known methods. During one revolution of the :brushmember'the position of each contact set at the distantpoint is signaled to the central point by means of a ground, the absence of ground, a;positive or negative battery, or any combination of such indications applied to-the signaling wires.

lhe principal difliculty .in the design of such systems lies in the provision of a temporary starting indication, which starts the rotating mechanisms-wheneVer a contact setchange its position.

The temporary starting indication may be given :by means of an extra-spring 0r segment on the contact set, e. g., of power station'circuit breakers, the movable armature of the contact set making temporary contact with the extra spring whenever'the contact set changes its position.

Allwsuch means are, "however, of a mechanical nature and cannot be used to signal the position-0f vmechanisms which lack said extra spring Most of the existing systems designed :on this basis are, therefore, very limited in their application.

The new signaling system according to this invention is of the synchronized stepping type. The system requires two metallic signalingwires between the distant and the central points. No earth :return connection is employed. The synchronization is achieved by very simple means, comprising ordinary telephone relays in a straight .direct current circuit.

The main difference between the new signaling system and known systems isin the method of givingthetemporarystarting indication for the rotating mechanisms.

One feature of the invention provides for the giving. of this indication in the form of a transient electrical surge in the secondary winding of a common transformer. This makes it -;possi-b1e-to apply the new signaling system to any type of .new :or existing signaling installation, even if eachcontact set comprises only two springs, i. e., one make or one tbreak'contact, which is the smallest practicable contact set spring combination.

.Accordingto anotherfeature of the invention a cold-cathode tube is provided for the purpose of receiving and registering the temporary surge indication.

In my new signaling system it is also possible to establish a telephonic connection between the control and the distant points over the signaling wires without interfering with the signal transmission proper.

The manner in which the new signaling system functions will now be described with the aid of the drawings, in which Fig. 1 is a diagram of the connections at the distant end, while Fig. 2 represents the connections at the central or supervisory point, only so much being shown as is necessary for a clear understanding of the invention.

In Fig. 1, IC designates one of a plurality of contact sets, which can be closed or open. The contact set is shown open.

Each contact set is provided with an individual resistance 1'1. One side of all these resistances is multipled and connected in common to the primary winding of transformer T1; the secondary winding of this transformer is connected to a potentiometer P, and also to the control electrode c2 of a cold-cathode tube L.

The cold-cathode tube is of the wellknown type, which requires a specific control gap breakdown potential VX to light or ionize the control gap between the two electrodes e1 and c2, and a much higher main gap breakdown potential Vy to light the main gap between the anode A and either of the two electrodes e1 and e2. Once the control gap has been ionized, a potential Vz, which is considerably lower than Vy, is sufficient to maintain a current in the main gap.

The control electrode 61 is permanently connected to the negative side of battery, while the control electrode 62 (usually referred to as the control anode) is connected to a biasing potential on the potentiometer in series with the secondary winding of transformer T1. The biasing potential, which is applied in order to increase the sensitivity of the arrangement, is considerably lower than the control gap breakdown. voltage,

so that normally the tube will not be operated. An electrical surge produced in the secondary winding of transformer T1 will be sufficient to increase the potential difierence between c2 and e1 or between c2 and A to a value, which is equal to or higher than the control gap breakdown voltage, or the main gap breakdown voltage.

The action of the electrical surge effect may be explained in the following manner:

Let it first be assumed that the contact of a contact set 10 opens. By removing the ground from the corresponding resistance 71, the potential of the common point is suddenly increased, thus causing a temporary change of the value of the current flowing through the primary winding of T1. This change will take place in a direction indicated by an arrow drawn in. full lines and will induce a surge in the secondary winding of T1 in a direction such that the potential of oz will be increased with respect to the potential 61. By a proper choice of the bias and of the dimensioning of transformer T1, this surge may be made to ionize the control gap.

Let it further be assumed that thereafter the contact set closes. By adding a resistance in the circuit the potential of the common point 0 will be suddenly lowered, causing also a temporary change in the value of the current flowing through the primary winding of T1. This change will take place in a direction indicated by an arrow drawn in dotted lines and will induce a surge in the secondary winding of T1 in a direction such that the potential of e; will be decreased with respect to the potential of the anode A. By proper design this surge may be made sufficient tobreak down the main gap directly.

It is obvious that the number of contact sets 7 that can be connected in parallel to one trans- ,cated on a control panel.

former is limited only by practical considerations.

It is quite possible, however, to connect several transformers to one cold-cathode tube, e. g. by connecting the secondary windings in series, as indicated in dotted lines in Fig. l, where a second transformer T2 is shown.

The anode of the cold-cathode tube is connected via the winding of a relay S1 to the positive pole of the battery.

SS1 designates the power magnet of a step-bystep selector switch of the well-known type used in telephone or similar systems. This switch is provided with a bank of terminals, of which three levels, viz. (11, b1 and 01 with corresponding brush members 021, 1 1 and 21 are indicated. It should, however, be understood that the invention is not limited to the use of any particular type of selector switch, but that any other types of single or two-motion selector switches may be employed without changing or modifying the principle of the invention.

Each contact set is connected also individually to an individual terminal in the selector switch bank.

The selector switch is further provided with a spark quencher Q, interrupter contact 11th and an off-normal contact ONC1. The latter closes its lower spring set when the switch is in normal position, and opens it when the switch is in any other position.

Fig. 1 shows further a group of controlling relays, the function of which will be explained later.

Key K11 simulates a contact set and is provided for test purposes.

The telephone set TA1 shown on the right-hand side of the drawing may be any type of common battery set connected to the two signaling ires wi and wz by means of two coupling condensers C12. The telephone set is fed over a retardation coil M1.

Key K12 is the telephone call key, and the purpose of it is to ring the bell at the central point as long as the key remains depressed.

In Fig. 2, SS2 designates the power magnet of a step-by-step selector switch of the same type as the one in Fig. 1. The switch has three banks of terminals as, b2, c2 and corresponding brush members $2, 2 and 22. The switch is provided with a' spark quencher Q2, an interrupter contact 111.152 and an off-normal contact ONC2. The latter closes its top spring set as long as the switch remains oiT-normal.

Each set of terminals in the banks 412 and b2 is connected to a pair of mechanically interlocking relays IE1 and IE2. Each pair of such relays corresponds to one contact set (IC in Fig. l). The interlocking relays are so designed that the operation of 1R1 will cause the closure of the lefthand contact, while the operation of 1R2 will close the right contact. When either relay is operated and closes its contact, the current may be removed from the winding of the relay without influencing the position of the armature.

Each pair of interlocking relays is associated with a. pair of indicating lamps IL1 and IL2, 10- These lamps are connected to give the following indications. Contact IC open: lamp IL2 lights; contact closed: lamp IL1 lights.

.Fig. 2 also shows a group of controlling relays, which will be later described.

A telephone set TA2 is connected in the same manner as set TA1 in Fig. 1.

Key K22 is the telephone call key, and functions in the same manner as K 2 in Fig. 1.

Key CK is the central point checking key, which will also be described later.

Starting of indicating mechanism Let it be assumed that the signal system is at rest and that both selector switches are in normal position.

Let it further be assumed that one of the indicator contacts opens. At that moment one resistance 11 is disconnected from ground, and this will produce as previously explained an electrical surge in the secondary winding of transformer T1, with the result that the breakdown voltage of the control gap is attained. The control gap, and subsequently also the main gap, will be ionized, and relay S1 will become energized. Relay St1 operates also via the off-normal contact ONC1 and the front contact of S1, after which relay St1 locks itself over its own front contact. The operation of S161 opens the anode circuit of the tube and since by this time the effect of the surge will have disappeared, the tube will become extinguished.

Relay H1 will become energized in the circuit via interrupter contact Int1, brush X1 and home terminal, front contact of relay S151, to ground.

When relay H1 closes its front contact, relay N1 will operate in parallel with H1. Relay N1 energizes the power magnet SS1 and operates relay B1 which connects battery to wire on and ground to 101 over the front contacts of relay F1 and retardation coil D1.

Relay E1 became energized in parallel with relay St1, thereby operating relay F1, which reversed the battery and ground connections to the signaling wire, for a purpose which will be explained later.

The battery connected to wire on will cause the operation of relay A22 at the control station (Fig. 2) but relay A21 will not become energized, because it is shunted at that moment by rectifier R21. Relay A22 in turn operates relay F2, which closes the energizin circuit for the power magnet of switch SS2.

When switch SS1 (Fig. 1) attracts its armature, it opens the circuit for relays H1 and N1. These relays are, however, made slow-releasing, so that sufiicient time remains to check and transmit the indication in a manner to be described later.

When finally relay N1 opens its front contacts, switch SS1 will complete its first step. Relay B1 releases whereupon the relays A22 and F2 are also released (Fig. 2). Switch SS2 will, therefore, also complete its first step.

As soon as the brushes of SS1 leave their normal position, contact ONC1 will open and relays ST1 and E1 release.

When the interrupter contact Int1 closes after the first step, relay H1 and subsequently relay N1 will operate from the ground at the terminals (11 of SS1. The cycle of operations above described will be repeated, with the result that the two selector switches will be driven in synchronism. step-by-step, until switch SS1 comes to rest on the home position. terminals after one complete revolution. In this position the ground connection to relay H1 is removed and both switches, therefore, stop rotating.

Let it now be assumed that one of the indicator contacts closes. In this case, as has already been explained above, the electrical surge in the secondary winding of T1 will cause the breakdown of the main gap of the tube, after which the opcl'ation of the circuit continues as above des ribed.

Transmission of contact set positions Every time switch SS1 stops on a set of bank terminals, to which an indication contact set is connected, a check is made over level In to determine, whether the contact set is open or closed. If the contact is closed, there will be a ground on the b1 level terminal, and if the contact is open, there will be no such ground.

If a ground is present, relay E1 will operate over .the brush y1, causing in turn the operation of relay F1, which will connect battery to Wire 1112 and ground to 201.

If there is no ground, the relays E1 and F1 will not energize, so that battery is connected to wire 101 and ground to wire 1.02.

In the control station the corresponding check for battery and ground is performed by relays A21 and A 2, which are shunted by two rectifiers R21 and R22 in such a way that A22 operates only with battery on wire 102 while relay A21 operates only with battery on Wire 1111. The relays A21 and A22 energize locally relays E2 and F2, respectively, and either one of these relays advances the brushes of switch SS2 in synchronism with those of SS1, once the home position has been left.

The arrangement is such that the first starting pulse is always given in the form of a battery on wire m2, which causes the relays A22 and F2 to operate. As soon as the brushes of SS2 leave the home position, relay G2 operates, after which the left front contacts of relays E2 and F2 are connected in parallel, until the brushes have completed their revolution.

Depending whether relay E2 or relay F2 has been operated, a ground is connected to relays IE2 or IE1 via brushes $2 or 1 2. This ground energizes temporarily one of the indicating relays, which locks mechanically and lights the corresponding indicating lamp.

The following table gives the relationship between the contact set position and the operation of the various apparatus involved. A sign indicates that a relay is energized, or a lamp lit, while a sign indicates that a relay is deenergized or a lamp extinguished.

1 Ground. 2 Battery.

Remote control from central point In any remote signaling system it must be possible for the central p int supervisor to check at any moment the correctness of his lamp indications. For this purpose it is necessary and sufiicient to provide the supervisor with means to start the selector switch at the distant point by a simple manoeuver at the central point.

According to the invention this verification is performed as follows:

As soon as the supervisor depresses the check key CK in Fig. 2, relays D2 and B2 energize and connect battery to Wire 1121 and ground to wire 102. This causes the operation at the distant point of relay A11, while relay A12 cannot operate clue to the shunting effect of rectifier R12. Relay A11 in turn operates relay G1.

When the supervisor releases key CK, relays D2, B2, A11 and G1 are de-energized, but relay G1 releases more slowly than relay A11, so that the ground at the back contact of relay A11 will be on long enough to energize relay Sti, which locks. Relay E1 energizes in parallel with S751.

The operation of relay St1 starts the advancement of the selector switches as explained above, and during the full revolution of the brushes the positions of all the contact sets are checked.

As soon as switch SS2 leaves the normal position, the check lamp CL lights as an indication that the starting operation has been successful.

In the preceding description the relays A11, A12, A21 and A22 were described as functioning on an electrical current of a predetermined direction by means of a properly poled rectifier or other nonlinear resistance connected in parallel to each relay. It is evident that the same result could be obtained by using ordinary polarized relays of any suitable design, the relays A11 and A12 and A21 and A22, respectively, being polarized in opposite directions.

Telephone call If a person at the distant point desires to establish a telephone communication with the central point, he removes the receiver and temporarily depresses the telephone call button K12, thereby operating relay B1. This relay connects battery to wire on and ground to wire 202, resulting in the operation of relay A21 at the central point. The latter in turn operates relay E2, which closes the circuit for a direct current bell, a regular telephone drop or any other suitable signaling device. The bell will ring, as long as key K12 remains depressed.

The supervisor removes the receiver, whereupon the conversation may take place. 'If the supervisor at the control station desires to call the distant point, he removes the receiver and depresses the telephone call key K22, thereby operating relay B2, This relay connects battery to wire 202 and ground to wire w1, resulting in the operation of relay A12 at the distant point. The latter closes the circuit for a bell, a drop or any other suitable signaling device. The bell will ring as long as key K22 remains depressed.

When the person at the distant point removes the receiver, conversation may take place.

It is obvious that the telephone conversation once established, is carried on without interfering with the signaling.

The supervisor at the control station should, however, not originate a telephone call while the check lamp is burning, because that might influence the correct receipt of the signals.

The person at the distant end can only originate a call, while switch SS1 is in normal posi tion. If key K12 is depressed, while the brushes of the switch are rotating, this has no effect.

8 Testing facility The person at the distant end can verify that the equipment starts out correctly by depressing the test key K11. B doing so he connects a resistance m in parallel to the resistance T1 and this has the same effect as if the contact set had been closed.

Alarms .TE, but this relay has not sufiicient time to leave its back contact during one revolution of SS2.

If, however, for some reason the brushes of SS2 are prevented from returning to normal within a predetermined lapse of time, the thermostatic relay will function, resulting in the operation of the alarm relay N2 via front contacts of the relays H2, TE and G2. Relay N2 locks to a back contact of key CK and closes the contacts for actuating an appropriate alarm signal. Relay N2 also closes the local circuit for the restoration of switch SS2 via its own interrupter and the offnormal contact ONC2. The brushes of the switch, therefore, return to normal and the switch cannot again be taken into use, before the supervisor has depressed key CK.

What is claimed is:

1. In an electrical signaling system, a variably operable first and second switch, two metallic wires between said switches, indicating means associated with the first switch, a plurality of mechanisms and a corresponding plurality of contact sets associated with the second switch, said mechanisms having a plurality of positions, cooperating contacts for each switch, a resistance for each contact set, a cold-cathode tube, means responsive to a change in the position of any of said contact sets to produce an electrical surge to ionize the cold-cathode tube, means for operating the second switch controlled by the tube, means for operating the first switch controlled by the second switch, and an actuating circuit for said indicating means controlled by said contact sets over said wires and the cooperating contacts of said switches.

2. An electrical signaling system according to claim 1, characterized in that one end of each resistance is connected to its associated contacts set, and a multiple connection from the other end of all said resistances to the primary winding of said transformer.

3. An electrical signaling system according to claim 1, a source of potential, means for applying a predetermined biasing potential to the control electrode of the cold-cathode tube in series with the secondary winding of said transformer, the biasing potential being lower than the value of the control gap breakdown voltage of the tube.

4. In an electrical signaling system, a central and a distant point, two metallic wires between said points, indicating means at the central point, a plurality of variably operable contact sets at the distant point, a switch at the central point having cooperating contacts, a switch at the distant point having cooperating contacts, a resistance for each contact set at the distant point, a

cold-cathode tube at the distant point, means responsive to a change in the position of any contact set to produce an electrical surge to ionize the cold-cathode tube, means for starting the switch at the distant point controlled by the tube, means for starting the second switch at the central point controlled by the first switch, and an actuating circuit for the indicating means controlled by said contact sets over said wires and cooperating contacts of said. switches.

5. The electrical signaling system according to claim 4 and in which the tube has an anode, two control electrodes, a main gap and a control gap, a source of biasing potential for one of said control electrodes, and means including a circuit operable when a contact set closes to produce an electrical surge of such a magnitude and direction as to cause the breakdown of the tube main gap, and to produce, when a contact set opens, a surge of such a magnitude and direction that it will, aided by the biasing potential, cause the breakdown of the tube control gap.

6. In an electrical signaling system, a central and a distant point, two metallic wires between said points, indicating means at the central point, a plurality of variably operable contact sets and a resistance connected with each set at the distant point, a switch at each of said points having cooperating brushes and terminals, automatic means for each switch to operate its brushes successively to engage all of its terminals, a transformer having primary and secondary windings, and a cold-cathode tube at the distant point, a path closed by any contact set including the resistance associated therewith to produce in the secondary winding of the transformer an electrical surge, a connection from said secondary winding to the cold-cathode tube to ionize it by said surge, means for starting the automatic opera tion of the switch at the distant point controlled by the tube, means for starting the automatic operation of the switch at the central point controlled by the other switch, and an actuating circuit for the indicating means controlled by the contact sets over said wires and the brushes an terminals of the two switches.

7. In an electrical signaling system, a central and a distant point, two metallic wires between said points, indicating means at the central point, a plurality of variably operable contact sets located at the distant point, a variably operable switch at the central point, a first relay responsive to positive and a second relay responsive to negative impulses connected at the central point with said wires, a variably operable switch at the distant point, other relays at the distant point for applying positive or negative pulses to each wire in a closed circuit, a cold-cathode tube at the distant point, means responsive to a change in the position of any contact set to produce an electrical surge to operate the cold-cathode tube, means responsive to the operation or non-operation of said tube variably to operate said other relays, means for operating the switch at the distant point controlled by the tube, means responsive to the operation of either the first or the second relay for causing the switch at the central point to perform one operation.

8. The signaling system according to claim '7, and circuits for said indicating means controlled by said first and second relays.

9. The system according to claim 7 and in which each switch has a bank of terminals and a brush cooperating therewith, a connection from each contact set to a different terminal in the bank of the switch at the distant point, and circuits for the other relays controlled over the last mentioned contact bank for determining whether a positive or negative pulse will be applied to a wire.

10. The system according to claim 7, and a pair of mechanically interlocking relays at the central point, and circuits therefore jointly controlled by the first and second relays so that the receipt of a pulse of one polarity will cause the operation and blocking of the first interlocking relay, while the receipt of a pulse of the opposite polarity will cause the operation of the second interlocking relay and the de-blocking of the first interlocking relay.

11. The system according to claim 1, a special signal at the central point, a circuit for said special signal controlled by the first and the second relays, and a calling button at the distant point for controlling said first and second relays.

WILLY POULIART.

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