GB546798A - Improvements in automatic reclosing circuit breaker systems - Google Patents

Abstract

546,798. Protective cut-out systems. BRITISH THOMSON-HOUSTON CO., Ltd. July 9, 1941, No. 8661. Convention date, July 11, 1940. [Class 38 (v)] In an automatic reclosing circuit-breaker system employing two timing systems, one of which recloses the breaker instantaneously once (as in the example given) or a given number of times, whereas the other performs a given number of time-delayed reclosures, the first system initiates the operation of the second system in the event of the breaker being still open when it has completed its timing operation In the Figure a time relay 13 'energized at the first tripping by overload relay 7, closes contacts 14, 15 in succession, the former contacts causing operation of the first system once, and the latter contacts controlling a timing means 23 such as described in Specification 406,961 for producing the delayed reclosures. On overload, relay 7 energizes trip coil 6 and also a relay 9 which closes hold-in contacts 10 and at contacts 11 makes the circuit of a relay 12, which makes a holding circuit at contacts 26, and of timing relay 13. Closure of contacts 14 of the latter energizes, over back contacts 27 of the breaker, a relay 16 which closes a holding circuit at contacts 29, and the relay 17 which energizes reclosing coil 4. When the breaker closes, contacts 27 open and de-energize these relays and. supposing the 'breaker stays closed, when contacts 15 of relay 13 close, a relay 31 is energized over back contacts 32, which relay holds itself in at contacts 33, and at contacts 35 de-energizes relay 12. Contacts 26 therefore open and allows relays 12, 13, 31 to return to their original positions. If, on the contrary, the breaker does not stay in, when contacts 15 are closed a circuit is made over back contacts 36 to the coil 18 of a lock-out relay 19 which picks up and is latched in at 20. In picking up, relay 19 firstly opens its own circuit and that of relays 12, 13 at contacts 25, secondly opens the circuit of relays 16, 17 at contacts 28, and, lastly, makes at contacts 37 and over back contacts' 38 the energizing circuit 39 of the timer 23. If the breaker stays in, the timer 23 at the end of its operations energizes over back contacts 40 the release coil 21 of latch 20, to render operative the instantaneous reclosing means.