GB621197A - Improvements in and relating to automatic reclosing electric circuit breaker systems - Google Patents

Abstract

621,197. Protective cut-out systems. BRITISH THOMSON - HOUSTON CO., Ltd. Nov. 24, 1944, No. 23438. Convention date, Nov. 24, 1943. [Class 38(v)] Each circuit-breaker at the section-ends of a sectionalized A.C. circuit is provided with automatic reclosing means operable when the circuit-breaker is opened by means responsive to a fault on the section, and means for preventing the reclosing of the circuit-breaker when the latter is opened by means responsive to an out-ofstep condition (other than power swings) on the section. The circuit of the trip coil 15 is completed through contacts 16, 17 of devices 10, 11, responsive to the phasedisplacement of the system generating sources, and contacts 18, 19 of the directional starting and ohm units 12, 13 respectively of a distance relay 14. The occurrence of a fault on the section causes contacts-19 to close, thereby tripping circuitbreaker A1 and closing auxiliary contacts 20 which close the starting circuit of an automatic reclosing device 21, the contacts 22 of which energize the circuitbreaker reclosing coil 23. In order to render the device 21 inoperative on the occurrence of an out-of-step condition, the circuit of coil 23 is provided with contacts 25 of a relay 26, the operating winding of which is connected in series with contacts 27 of an ohm relay 28 and in parallel with contacts 30, 31 closed by the closing members of contacts 16, 17 of relays 10, 11. Relay 26 has a short delayed closing time and a long delayed opening time, and the reach of relay 28 is considerably longer than that of relay 14, so that for an out-of-step condition, contacts 27 close first, thereby opening contacts 25 before the circuitbreaker is tripped by the closing of contacts 16-19. In the case of a fault, relay 26 is not energized long enough to open contacts 25 before it is short-circuited by contacts 30, 31. If circuit-breaker A1 fails to remain closed for a predetermined time after any reclosure, reclosing device 21 and the drop-out time of relay 26 may be adjusted so that the return of relay 26 to its normal position after energization in response to an out-of-step condition, does not effect the reclosure of the circuitbreaker. Specification 441,606 is referred to.