GB406961A - Improvements in and relating to automatic reclosing circuit breaker systems - Google Patents

Abstract

406,961. Protective cut-out arrangements. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.- (Assignees of Anderson, A. E. ; 725, Stanbridge Road, Drexel Hill, Cox, V. L. ; 3, Pennock Terrace, Lansdowne, both in Pennsylvania, and Wright, F. S.; 209, Hammond Avenue, Kingsport, Tennessee, both in U.S.A.) Nov. 27, 1933, No. 33190. Convention date, Nov. 26, 1932. [Class 38 (v).] In an automatically reclosing circuit-breaker system, a substantially instantaneous reclosure of the circuit-breaker 1 after the initial opening thereof is effected by means of a control device comprising an electromagnet 24, a set of normally open contacts 20, 21 closed in response to energization of the electromagnet, and arranged to remain closed on its subsequent de-energization, normally closed contacts 19 opened on energization of the electromagnet 24 and subsequently remaining open, a second set of normally open contacts 22, 23, arranged to be closed and opened respectively in response to the energization and subsequent de-energization of the electromagnet, means responsive to the initial opening of the circuit-breaker for completing an energizing circuit for the electromagnet 16 through the contacts 19, and means responsive to the closing of both sets of normally open contacts for effecting the closing of the circuit-breaker and the de-energization of the electromagnet 24. The circuit-breaker shown has a closing coil 4 and is held on by a latch 5, the latch being tripped on the operation of any one of the overload relays 7, 8, or 9, in the supply lines 2. On opening of the circuit-breaker, the energizing circuit of the electromagnet 24 is completed at the back contacts 25 of the circuit-breaker, whereupon contacts 22, 23 close, and a latch 18 is tripped to release the core 17, which drops to close contacts 20, 21 and open contacts 19. Contacts 22 complete a hold-on circuit for electromagnet 24, while closure of contacts 20, 22 energizes a relay 26 through contacts 42 on the latch 5. The relay 26 completes an energizing circuit for the closing coil 4 of the circuit-breaker, and at the same time energizes a winding 32 to release a timing device 28 driven by a motor 29. As soon as the circuit-breaker closes, the circuit of the winding 24 is interrupted at the contacts 25, and the winding cannot be re-energized until the core 17 has been restored to its original position. After an interval, the timing device 28 closes contacts 34, and, if the circuit-breaker is then open, a relay 36 is energized through contacts 25, and prepares a circuit for the relay 26, this circuit being closed at the contacts 35 on further rotation of the timer. The circuitbreaker is then closed by energization of the coil 4. If it opens again, it is reclosed after a time interval by the timer 28. After the timer has closed and opened contacts 34, 35 a predetermined number of times, it disconnects contact 39 from contact 40 and connects it to contact 41 and, if the circuit-breaker is then closed, completes the circuit of a coil 27 which restores the core 17 to its original position in which it is held by the latch 18. If, however, the circuit-breaker is open at the time the contacts 39, 41 are connected together, the coil 27 is not energized, and no further automatic re-closing of the circuit-breaker can take place until after a manual operation has been performed. In a modification, the latch 18, instead of holding the contacts 19, 20 and 21 in their normal positions, holds them in their operated positions, and the winding 27 is arranged to trip the latch. In another modification, the timer is arranged to connect the contacts 39, 41 after such reclosure, in order to render the instantaneous reclosure device operative after each time-delayed reclosure.