Patent GB-208724-A (GB)
Title: Improvements in automatic reclosing electric circuit interrupter systems
IPC: H02H3/06
Filed: 1923-12-20
Abstract: 208,724. Metropolitan-Vickers Electrical Co., Ltd., (Assignees of Moss, C. M., Farley, W. R., and Peterson, A. J. A.). Dec. 21, 1922, [Convention date]. Protective arrangements.-An automatically reclosing circuit-breaker system for parallel feeders has an arrangement of relays in association with each feeder circuit and a control arrangement of relays common to the whole system. Upon the occurrence of abnormal conditions in any feeder the control relays co-operate with the relays of that feeder to produce a predetermined switching cycle, the control relays being arranged to deal with one feeder only at a time, and a feeder being arranged to be locked out in the case of a persistent overload. A main circuit 1 supplies a number of parallel feeders such as 2 through circuit breakers 4. Each interrupter 5 has a closing coil 10 controlled by a relay 18 and a trip coil 11 controlled by a timelag overload relay 12 fed from a series transformer 13. Associated with these relays are a cut-off relay 19 and lock-out relay 26 and a further time-limit relay 32 fed from a potential transformer 33. The control group of relays common to the whole system comprises a motor-driven selector relay 51, a control 52, and a motor driven timing relay 53 having a spring-returned' electromagnetic clutch between the driving shaft and the rotary contact member 69. Relays 19, 26 and 52 have each in addition to the operating windings 23, 29, 64 a holding winding 24, 30, 65. Normally when the interrupters are closed a maintaining circuit for the coil 23 of the cut-off relay 19 is completed from the control supply, bus bars 75, 76 through back contacts of the interrupter. On operation of the overload relay 12 the trip coil 11 is energized and the circuit-breaker opened, relay 19 also being released. A circuit for the motor 54 is now completed through back contacts of the circuit-breaker 4 and of the relay 19. When the motor has moved the drum to the required position the coil 64 of the relay 52 is energized through the resistance. 35 and breaks the motor circuit a small current also passing through the relay 18. As the relay 52 operates the circuit of the holding coil 65 of the relay 52 is completed through the resistance 66. The operation of this relay also short-circuits the operating coil 64 and the consequent increase of current in the coil 18 causes operation of the closing coil 10 which closes the circuit-breaker 4. The relay 19 also closes, de-energizing the relay 18 and coil 10. If the faulty conductor has been cleared the potential relay 32 closes after a predetermined time and in conjunction with the relay 19 short-circuits the maintaining coil 65 of the relay 52 which is released, the control relays now being available for dealing with another feeder. If the fault is still present in the feeder 12 the circuit breaker 4 is again opened by the relay 12. The relay 19 is not, however, released, as its maintaining coil 24 remains energized through contacts on relays 51, 52 and a resistance 73. This relay is not released until the timing relay which commences to operate when the relay 52 is closed steps round the contact member 69 to join contacts 70 and short circuit the coil 24. Similar re-closing cycles occur for a second and third time in the case of persistent overload after which the contacts 72 are bridged and the circuit of the lockout relay 29 completed. A maintaining circuit 30 is then completed for this relay which co-operates with the relay 19 to short-circuit the coil 65 and release the relay 52. The control group of relays is now available to deal with another faulty feeder, the feeder 2 being definitely locked-out of circuit by the relay 29.