Patent GB-542583-A (GB)
Title: Improvements in high speed reclosing mechanism for electric circuit breakers
IPC: H01H75/04
Filed: 1940-07-17
Abstract: 542,583. Automatic circuit-breakers; actuation of switches. BRITISH THOMSON-HOUSTON CO., Ltd. July 17, 1940, No. 11796. Convention date, July 18, 1939. [Class 38 (v)] A circuit-breaker is automatically re-closed after it has made only a portion of its opening stroke sufficient to extinguish the arc at the contacts and thereafter, if again tripped, to be prevented from further automatic re-closure, thus providing clearing of permanent faults and minimum disturbance with arcing faults. The first tripping operation is effected by one trip coil 22 acting upon one latch, the re-closing operation causing a relay 45 to transfer to a further trip coil 15 acting on a toggle L' to produce the second tripping and complete opening of the breaker. Closure is effected by a cam 1 the shaft 6 of which is rotated clockwise by a motor M through gearing 5. The cam is engaged by a roller 8 on a lever 7 the pivot 9 of which is normally held by toggle L<SP>1</SP> and latch 12, the lever 7 being pivoted to the contact-operating rod 2 through a lever 3 pivoted at 4. In the closed position shown, a prop 17, pivoted at 19, has been snapped by spring 117 into retaining position from which it can be driven by the impact of a hammer 18, impelled by spring 23 and acting on a roller 17', when a detent 21 is deflected by the coil 22. During the opening operation, the hammer is reset by the part 53 of a member 50 which is pivoted at 50' and engaged at 51 by a roller 52 on the lever 3. The toggle L' is also automatically reset during the opening movement in which the lever 10 moves anti-clockwise. During the first opening movement, lever 3 closes a contact 43 and at the end of a complete opening movement, it opens contacts a, a'. Automatic tripping is effected by closure of contacts fr<SP>1</SP> by trip relay FR, energizing 22 over contacts a and contacts tr' of relay 45, so moving the prop 17 clear of roller 8 which drops on to the cam 1 at an intermediate surface in which it is held, against the action of spring 38, by a member 39 engaging a pin 30. When contacts 43 close, a circuit is made over O<SP>1</SP>, a<SP>1</SP>, tr<SP>2</SP> to (1) relay 45 which picks up and opens contacts tr<SP>1</SP>, tr<SP>2</SP>, and closes tr<SP>3</SP>, to (2) contactor coil 2A which picks up and makes a holding circuit for itself at mr<SP>2</SP> and the motor circuit at mr<SP>1</SP>, these circuits including, respectively, the contacts s<SP>2</SP>, s<SP>1</SP> of a switch S, and to (3) a winding 26, which, when the breaker reaches the closed position and pin 30 drives member 31 to actuate a lever 32 and rod 33 to open contacts s<SP>1</SP>, s<SP>2</SP>, retains the armature 28 in attracted position and contacts s', s<SP>2</SP> open. Thus the motor is stopped and spring 38 restores the cam 1 to the position shown. If, however, the fault persists and the breaker again trips, since contacts tr<SP>3</SP> are still held closed by the dashpot tr<SP>4</SP>, closure of contacts fr<SP>1</SP> energizes trip coil 15 over contacts a, tr<SP>3</SP>, thus collapsing the linkage L' and moving the lever 39 clear of the pin 30, whereby the cam 1 is driven by its spring 38 so that the low point thereof is engaged by the roller 9, corresponding to the full-open position of the breaker, in which contacts a, a<SP>1</SP> are open and hence 27 de-energized, but pin 30 has moved arm 31 so that spring 32 can re-close contacts s<SP>1</SP>, s<SP>2</SP>. In order to re-close, the coil 24 must be energized by manual closure of switch C, which also energizes 45 to transfer the tripping to coil 15 and ensure complete opening if tripping again occurs. Manual tripping can be effected by changing over switch O to contact o<SP>2</SP> to energize coil 22 over contacts a, tr<SP>1</SP>, no automatic re-closure being possible since contact o' is now open. Buffers 35, 37 are provided for the end of each movement. Specifications 484,861 and 526,422 are referred to.