Patent GB-591043-A (GB)
Title: Improvements in electrical supervisory control systems
IPC: H02J13/00
Filed: 1945-04-28
Abstract: 591,043. Electric control systems. AUTOMATIC TELEPHONE & ELECTRIC CO., Ltd., and BURNS, G. A. April 28, 1945, No. 10754. [Class 40 (i)] A system for the control and supervision of circuit breakers comprises a main collecting sub-station CS, Figs. 1, 3, which is connected to a central control and indicating point C, a number of subsidiary collecting sub-stations such as CSA, which are connected to the main collecting sub-station and a plurality of terminating sub-stations such as TSA, which are connected to the main, or one of the subsidiary collecting sub-stations. Signalling between the control point C and a terminating sub-station TSA involves the reception of a signal at each of the collecting sub-stations in the intercommunication path and the transmission forward of a different signal. Intertripping arrangements are provided, i.e. means whereby if a circuit breaker at (say) CSA is automatically tripped by a fault an associated circuit breaker at (say) TSA is tripped also. Remote control of circuit breakers at terminating sub-station TSA. Apparatus at the central station C (not shown) selects a particular circuit breaker for control by sending a constant total code made up of normal and reverse polarity impulses. At station CS, switches (not shown) respond respectively to the normal, the reverse and to impulses of both kinds. The first switch selects a " virtual circuit breaker " consisting of two relays individual to an actual circuit breaker at a distant station and the others, provided that a correct code has been received, send a signal back to the control.station which then sends an action (i.e. trip " or " close ") signal to actuate one of The two relays, e.g. the relay S, Fig. 4. This starts an allotting switch F, which drives to a position marked by the change-over of contact S2 to associate the line and sending arrangements with this relay. As a result, relays KR, E pull up and connect battery in the normal direction via LD to the outgoing line 14, 15. LD energizes BP, which interacts with E. As a result, impulses are sent over the line to the stepping magnet of local switches A, B, relay PT pulling up to reverse the polarity of the line impulses and to cause the local impulses to step B instead of A, when wiper A2 reaches the position marked by relay S. When wiper B1 reaches the marked position, BP is held energized in series with K, which causes the restoration of the end of the line to a receiving condition. At the incoming end, relays N, R repeat the normal and reverse impulses respectively to driving magnets AAM and BBM in series with HR which is followed by HRA, HRB, HRC. At the end of impulsing, HR falls and provided a correct code has been sent, H pulls up and energizes the interposing relay controlling the selected circuit breaker via AA4. Shortly afterwards the relapse in turn of the sluggish relays HRA, HRB release HRC to terminate the signal and restore the circuit to its normal condition. The interposing relay at CSA functions as a start relay S in another start circuit, Fig. 4, which is connected with a signal send circuit, Fig. 5, connecting the outgoing end of the line from CSA to TSA. At TSA the pulses are received by equipment such as Fig. 6, to bring about the control of the desired circuit breaker. Signalling of the new position of the circuit breaker to sub-station CSA. Auxiliary contacts AC1, Fig. 3, of the circuit breaker complete a circuit for a magnetic locking relay M, of the type described in Specification 515,529, [Group XXXVII], in series with the upper winding of a relay RSR. Relay RSR operates and short-circuits its upper winding to allow relay M to operate and change its contacts to the position corresponding to the new position of the circuit breaker. Relay RSR also energizes relay SE, thereby changing the line over to the sending condition and operating relay EE. Relay SER operates over the loop at the distant station and energizes a switch DDM in parallel with relay DP. Relays DP, EE interact to cause impulses to be transmitted to DDM and over the line, SER being shunted during impulsing. Relay RSR releases on the first step. As the wiper of the DD switch advances relay RV operates via the contacts AC1 of all circuit breakers having these contacts in the upper position and reverses the polarity of the signal impulses. At CSA relays I, O respond respectively to normal and reverse polarity impulses, operating relays IN, OUT in series with relay DR which repeats all impulses to a switch magnet DM which thus operates in synchronism with the switch DD at TSA. Magnetic locking relays CON are set, if necessary, to the positions corresponding to those of each of the distant circuit breakers in successive positions of D. In response to a change in position of a virtual circuit breaker, as represented by the relay CON, signalling from CSA to CS and from CS to C takes place as from TSA to CSA. When a circuit breaker changes position during an indiration signalling cycle relay RSR re-operates and locks via position 3 of bank. DD3. At the end of the cycle with relay RSR still operated a further cycle will commence during which the new position of the circuit breaker is communicated to CSA en route to the control room. Faulty operation. If a sub-station does not receive a full train of impulses the receiving D switch is not stepped through a complete cycle and hence when relay SR releases on the completion of impulsing relay RP operates in series with magnet DM. Magnet DM drives the wiper to the next position, where the driving circuit is opened and relay RP releases. During the operation of relay RP a reverse polarity pulse is sent over line conductors 14, 15 to the sub-station which sent the indication signal and relay R thereat operates and brings up relay RPS which operates and energizes relay RSR and also disconnects relay SER. At the end of the reverse pulse, relay RPS releases and relay SER then operates and the initial signal is thus repeated. Intertripping arrangements. If a circuit breaker at CSA trips due to a fault, contacts FPRI of a fault protection relay, Fig. 3, operate the associated relay S to bring about the operation of a particular circuit breaker at TSA. Both circuit breakers signal their new position to the control room. Additional arrangements. Meters at the control room can be operated by voice frequency impulses which are superimposed on the signalling channel but are arranged to byepass the line signalling relay groups in the various sub-stations en route to the control room. A different frequency is allocated to each substation and appropriate receivers are provided at the control room. A miniature automatic telephone system can be superimposed on the signalling system using weak currents for selection which are effective on sensitive relays connected in circuit with the line relays I, O, N, R.