Patent GB-214635-A (GB)
Title: Switching systems for electric transmission circuits
IPC: H02H11/00
Filed: 1924-04-16
Abstract: 214,635. Metropolitan-Vickers Electrical Co., Ltd., (Assignees of Peterson, A. J. A.). April 21, 1923. [Convention date]. Protective arrangements; switching systems.- In a transmission system, two circuit-breakers are each provid'ed with opening and closing coils and interlock switches whereby, when one of the circuit-breakers is closed or opened (at will or automatically on overload &c.), the corresponding closing or opening coil on the other circuitbreaker is energized to cause it to operate in a similar manner. The action in sequence may be extended to more circuit-breakers. As shown in Fig. 1 applied to a supply through a transformer 2, a circuit-breaker 3 is located in the primary side and another circuit-breaker 5 in the secondary side. Interlock switches 8, 10, 9 and 28, 30, 29 are provided on the two circuitbreakers which have closing coils 6, 26 and opening or trip coils 7, 27. Relays 11, 31 control the coils 6, 26 and the relay 11 is controlled manually by the two-way switch 12, automatically in accordance with predetermined conditions of overload &c. by relay 13, and also by the cut-off relay 14 and the lock-out relay 1.i. The cut-off relay is shown in the normal position and, when raised by the coil 18 to the attracted position, it is held by a resetting coil 20. The lock-out relay is manually reset. To connect the: supply the switch 12 is closed in its lower position, thereby energizing the relay 11 through contacts 16 and 21 from a local source. The relay 11 closes the circuit 6 and the circuit. breaker 3 closes. The interlock switch 8 is now closed and completes the circuit of the closing coil relay 31 of the other circuit-breaker, whereupon that closes also. The closure of 8 energizes also the coil 18 of the cut-off relay so that the switch 16 opens the circuit of both the coil 18 and of the coil of the reclosing relay 11, with the result that the closing coil of circuit-breaker 3 is opened. The closure of the circuit-breaker 5 effects also the closure of auxiliary contacts 28 thereby energizing its cut-off relay 34 and opening the closing circuit of 26. The circuit breakers consequently remain in the closed position, until unlocked by their opening or tripping coils. To disconnect the transformer, the switch 12 is closed in its upper position, thereby energizing 7 and tripping 3. In opening, the circuitbreaker opens the tripping circuit at 9 and closes the contacts 10 completing (i) the circuit of the tripping coil 27 and releasing circuitbreaker 5 and (ii) the circuit of the reset coil 20 and consequently breaking contact at 17 and making it at 16 so that a circuit is prepared for reclosure of 3. Similar disconnection of the transformer at both sides may be automatically effected on overload by means of the overload relay 41, and, in the event of persisting abnormal conditions, a relay 43 which may be of the thermal type opens the lock-out relay 15 which may be reset only by hand. The extension of the switching system to a third current-breaker located on the far side of a bus-bar supplied through the circuit-breaker 5 is described' also. The third-breaker is connected with a third cutoff relay and the second breaker controls the circuits of the third in the manner described for the two circuit-breakers in Fig. 1.