GB664907A - Improvements in and relating to transitory electroresponsive control apparatus - Google Patents

Abstract

664,907. Electrically-tripped switches. BRITISH THOMSON-HOUSTON CO., Ltd. Dec. 22, 1949. [Dec. 30, 1948] No. 32840/49. Class 38 (v). In order to prevent "pumping" of the reclosing solenoid of a circuit-breaker, irrespective of whether a master switch is held closed or not, the solenoid, when energised, is arranged to open its own energising circuit. A relay 16 has two windings 80, 81, the latter normally being short-circuited by a switch 103 and the former being energized on closure of a push-button master switch 112, so as to move the core 69 down and pivot a lever 72 clockwise about its pivot 73 against the action of a spring 76. A plunger 120 resting on the left-hand end of lever 72 is thereby raised to extend a toggle 52, 53, and the switch 103 is opened by a member 107. Link 52 has a fixed pivot 54 and is shaped to engage a roller 60 on the end of link 53 which is formed by two spaced arms, the free end of link 52 being movable in the space. Extension of the toggle pivots a contact arm 30 clockwise to close contacts 27, 28 in the circuit of winding 12 of solenoid 10, auxiliary contacts 42, 43 being closed at the same time to complete a lock-in circuit for winding 80. Energization of winding 12, lowers the core 13 to close the circuit-breaker and an extension 98 of the core pivots a lever 94 clockwise to raise a plunger 85 against the action of a spring 91 and so lift link 52 from roller 60. The toggle is thus broken and the arm 30 is swing counter-clockwise by a spring 48 to open the contacts 27, 28 and 42, 43. The winding 12 is thus de-energized and spring 91 restores the plunger 85, lever 94 and core 13 to their original positions. If the push-button 112 has been released, the winding 80 is also de-energized and the links 52, 53 move back to the Fig. 4 position and re-engage. If however, push-button 112 is still depressed, the winding 80 is energized by the reduced current through the current limiting winding 81 which is placed in circuit when the contacts 42, 43, which normally short-circuit it, open. The links 52, 53 then remain in the Fig. 6 position until the windings 80, 81 are de-energized by opening switch 112.