Patent GB-652127-A (GB)
Title: Improvements in electric systems of remote control and/or supervision
IPC: H02J13/00
Filed: 1948-08-16
Abstract: 652,127. Electric selective signalling. GENERAL ELECTRIC CO., Ltd., and FIELD, R. W. G. Aug. 16, 1948, No. 21577. [Class 40 (i)] In a code signalling system for remote control, and/or supervision, e.g. of circuit-breakers, involving reciprocal control of transmitter and receiver at each code step, the impulses in one direction are of constant length whereas the impulses in the other direction are of variable length, long or short, depending on the information to be sent. The code elements may be current impulses or breaks in the line current. The invention is described for selectively indicating at a control station, Fig. 3, the change in state of any one of a group of eight circuitbreakers at a remote power station, Figs. 1, 2, but by duplicating the equipment control operations may be effected. Also, there may be several groups of apparatus in which case the signal is divided into parts indicative of the group, the circuit-breaker, &c. within the group and the operation required or to be indicated, respectively. Associated with each circuit. breaker is a relay PA, Fig. 1, normally energized over an auxiliary switch CL or OP depending on whether the circuit-breaker is " closed " or "open." On a change of state of a circuit-breaker the auxiliary switch positions are reversed causing momentary de-energization of the associated relay PA. This energizes an associated relay WA which locks at wa1 and energizes a relay XA. Relay XA locks over its left-hand winding in series with a relay MS, causes WA to relapse, and at contact MS1 ensures that an "indication" signal initiated from any other circuit-breaker during transmission has to await its turn. The XA relays associated with the eight circuit-breakers have their XA3 contacts strapped across either relay NA or NB to one of the relays NW, NX, NY, NZ so that a selective combination of two of these relays is energized dependent on the circuit-breaker concerned. In the example shown NA, NY are energized. Relay MS operates a relay S, Fig. 2, over its upper winding, to send a line impulse over L1, L2 to operate a line relay CX at the control station which causes relays CK, CS to operate in turn and lock; relay CS, at contacts cs3, sends an impulse back over lines L3, L4 to operate a line relay TA, Fig. 2, at the power station which operates a slow-to-release relay TB which releases relay S and operates relay TBA slowly. As relay S relapses the line impulse over L1, L2 ceases, and at the control station relay CX releases to operate a relay CF. This preliminary signalling having been completed, the selective signalling commences when slow-tooperate relay TBA at the power station operates, whereupon relay S re-operates, locks over its lowest winding and sends the first selective impulse over line L1, L2 to operate relays CA, CB at the control station in turn. Relay CB is slow to release and remains in its energized position for the duration of the selective impulse train. It operates slow-to-release timing relay CL and energizes the reverse winding R to release relay CS, whereupon the preliminary revertive line impulse over L3, L4 ceases and releases the line relay TA at the power station. Relay TA in releasing operates at TA3 relay TC and relays TE, RA in series. Relay TE at TE 1 energizes the reverse winding R of relay S to release it, whereupon the line impulse over L1, L2 ceases and relay CA at the control station relapses, causing relay CC, and seriesconnected relays CE, AA to energize. Relay AA locks over its upper winding, de-energizes the slow-to-release timing relay CL and at contacts AA2 reoperates relay CS to start the first selective revertive impulse over lines L3, L4 to the power station, where line relay TA reoperates relay S over contacts NA1 of relay NA to start the next line impulse over L1, L2 to the control station. Here line relay CA operates, whereupon, CL is re-energized before it has had time to release, relay CD operates in series with CC, and CS releases to stop the first revertive signalling pulse over L3, L4 to release line relay TA at the power station. TA releases TC and S to stop the second impulse and operates TE in series with RB. The consequential release of the line relay CA at the control station releases CC and operates CE and AB in series. In this manner it will be seen that the relays S, CS interact to produce the line impulses and revertive impulses and that a chain of relays RA, RB, RC, RD at the power station are operated sequentially as successive revertive selective impulses over line L3, L4 cease, and a corresponding relay chain AA, AB, AC, AD at the control station is sequentially operated asynchronously as the corresponding pulses over line L1, L2 cease. The duration short or long of the revertive line impulses over L3, L4 is determined by the combination of relays NA ... NZ, Fig. 3, and chain relays RA, RB, RC operated, contacts of these relays determining whether or not a time delay relay LA, Fig. 2, is switched in to delay the energization of relay S upon energization of the line relay TA. The line impulses over L1, L2 are, however, always of the same length, i.e. short. When a long revertive impulse results from the delayed energization of relay S, the operation of the line relay CA by S occurs after the timing relay CL has released, whereby over contacts CL2 a relay of the chain BA ... BD is operated as the corresponding relay of the chain AA ... AD operates. In the example quoted with relays NA, NY operated the selective impulses reverted are short, short, long, short, long. The first impulse is the preliminary impulse. the next three are the selective impulses proper and the last impulse, always long, a terminating impulse for resetting purposes. In the relay chain BA ... BD, the relays BB, BD only are operated corresponding to the two long pulses in the impulse chain and over contacts of these relays an indicator relay KH is operated; it locks over an acknowledge key AK, and lights a lamp indicative of the operative circuitbreaker over contacts KH2. All other relays including MS, Fig. 3, are reverted to normal by the terminating impulse, when the apparatus is ready for transmission of a further " indication " code. Modifications. Control operations may be performed by substituting control switches for the auxiliary switches of the circuit breakers and arranging for the KH relays to perform the operations. Both indicating and control may be effected by duplicating the equipment and providing a relay to change over from one operation to the other. Testing. Faults such as dirty contacts stop impulsing. In this case a switch such as F1, and a lamp bank may be provided at both stations to indicate the point in the impulse cycle of the fault. Since a constant number of impulses is used for each operation, a "total code " check may be effected before an operation is performed by providing further contacts on the last relay in a chain such as RD or AD, in series with any indicating or control mechanism.