GB545482A - Automatic reclosing circuit breaker operating mechanism - Google Patents

Abstract

545,482. Automatic circuit-breakers. BRITISH THOMSON-HOUSTON CO., Ltd. Feb. 17, 1941, No. 2155. Convention date, Feb. 17, 1940. [Class 38 (v)] A circuit-breaker operating mechanism of the trip free type comprises a pair of latches, either of which can release the breaker, and a faultresponsive trip coil which operates one of the latches when the breaker is in normal closed position and both latches for their trip free operation only. In the adaptation of a circuitbreaker as described in Specification 490,641, to automatic reclosure, a chain 4 interconnecting the spring-controlled operating rod 2 with the plunger 1<SP>1</SP> of the closing solenoid 1 is normally held taut by a roller 5 on a bell-crank lever 6, which is pivoted at 7 and held stationary by engagement' of a roller 8 on its other end with a latch 9 pivoted at 10. The plunger 1<SP>1</SP> is held in closed position by a toggle 11, 12 itself retained by a roller 16 engaging a latch lever 17, which lever is adapted to be deflected, for normal tripping, by the plunger 21 of coil 22 engaging a lever 19 co-pivoted with 17 at 18 and operating 17 through a pin 20. On overload, relay FR closes contacts fr<SP>1</SP> to energize 22 over contacts a which open when the breaker opens. At a predetermined point in the opening stroke, contacts b close a circuit for a solenoid SR over contacts L, which are closed as soon as the plunger 1<SP>1</SP> rises, contacts b, and contacts m<SP>2</SP> of a manual snap switch, M. In operating, SR makes its holding circuit at Sr, and at contacts 28 energizes the coil 1 in parallel with a further coil 30. The latter acts to straighten a toggle 25, 26 interconnecting lever 19 and a lever 23 which is brought up to a pin 24 on lever 9. If the fault persists when the breaker is closed and relay FR again energizes coil 22, the movement of lever 19 and latch 9 collapses the chain 4 and spring 3 opens the breaker. If there is no fault, however, contacts L open and de-energize relay SR and coil 30, so restoring the toggle 25, 26 to the position shown. If the switch M is changed over, manual tripping without automatic reclosure occurs. In Fig. 2, a floating lever 43 is retained by a latch system 48, 50, which is operative during normal conditions, and by a latch 45 which is operative during closing only. A pin 63 on lever 50, which is co-pivoted with latch lever 48 at 51 and drives the latter by means of pin 54, engages in a slot 62 in a lever 61 which is linked at 60 to latch 45. Normally the pin 63 moves along the part 62<SP>1</SP> of the slot and does not operate the latch 45, but during closure, when the latch roller 49 is engaged and driven by the plunger 1<SP>11</SP> of the coil 1, and operation of the latch 48 can therefore have no effect, an extension 64 of the plunger lifts lever 61 so that pin 63 engages the lower slot-part 62<SP>11</SP> thus enabling the trip coil to operate latch 45.