GB420653A - Improvements in automatic circuit breakers - Google Patents

Abstract

420,653. Automatic circuit-breakers; snap-action switches. SHEVLIN, J. T., 15, South Street, Finsbury, London. June 12, 1934, No. 17402. [Class 38 (v)] In a push-button switch with automatic release provided with two contact-members 3, 5 in the same circuit, the circuit being made by the member 5 and broken by the member 3, a spring 14 is stressed, preferably through toggle links 10, 11, on depressing the button 1, and serves to impart a sudden movement to the member 5 in the switching-in operation and a sudden movement to the member 3 in the switching-out operation, which movements cannot be retarded by the push-button. The spring 14 surrounds a rod 15 carrying the contact-member 5, and is placed in compression, on depressing the push-button 1, by a member 13 to which the toggle lever 11 is pivoted. The member 13 is secured to a slide 2 carrying the contact-member 3, which is moved into the circuit-closing position on depressing the button, but a rod 8 carried by the button extends through an opening in an extension of the rod 15 and prevents movement of the latter. On releasing the button, the rod 15 is freed and the contact member 5 is moved into engagement with the fixed contacts 6 by the spring 14. As long as the circuit remains closed, further operation of the push-button 1 is prevented by the extension of the rod 15. When the toggle is upset by the energization of an electromagnet 17 which attracts an armature 16, the circuit is rapidly opened at the contact-member 3 by the action of the spring 14, and the contact-member 5 is subsequently moved into the open position by the engagement of the member 13 with an abutment on the rod 15. A second pushbutton may be provided for actuating the armature 16 when it is desired to release the switch by hand. The switch is particularly adapted for tariff supervision. In the arrangement shown in Fig. 6, the release coil 17 is switched in by a thermostat 19 in the circuit to be controlled, and variations in the surrounding temperature are compensated by providing a co-operating contact on another thermostat 20, the distance apart of the contacts on the two thermostats being adjusted by a screw 21 for determining the value of the current at which the switch is opened. An additional thermostat may be provided to close a preliminary alarm circuit before the switch is opened. In the arrangement shown in Fig. 10, the circuit of an alarm device 31 is closed through thermostats 20, 40. This circuit includes a heating coil 42 surrounding another thermostat 41 which is adapted to close the circuit of the release coil 17 after an interval.