GB510658A - Improvements in or relating to thermally controlled delayed action electric switches - Google Patents

Abstract

510,658. Electrically released switches. MANNHEIMER, G. Dec. 6, 1938, No. 35489. Convention date, Jan. 15. [Class 38 (v)] A switch with delayed action, such as may be used in staircase lighting, is held closed against a spring by a thermally controlled catch which releases a movable part step-by-step to open the switch, the catch meanwhile first rotating in one direction about an axis in one direction, and then about a second axis in the other direction. A button 3 is pressed down and held against a spring by a catch 11 which is pivoted at one end of a thermal element 13 and is pulled by a spring 15 across two lugs 5 and 6. In this position a heating coil 24 of the thermal element 13 is closed by the engagement of contacts 17, 18 of which 17 is electrically connected with a contact 20 which bridges contacts 21, 22 and closes the circuit to a load 25. The thermal element 13 then bends about a fixed support 14 into the position shown in Fig. 5 causing the catch 11 to pivot about an edge 9 on the lug 6 until it is free from the top edge 7 of the lug 5. The button 3 then springs up until an edge 10 made by cutting a step in the lug 6 engages the catch 11, and the heating circuit 24 is broken although the main circuit still remains closed. The thermal element now cools and causes the catch 11 to rotate about an edge 8 on the lug 5 until the lug 6 is released and the push button moves up to open the main circuit. The heating up time is short compared with the cooling time which can be adjusted by rotating the support 14.