GB562275A - Electro-magnetic switches - Google Patents

Abstract

562,275. Electromagnetic switches. HINKS, B. Dec. 21, 1942, Nos. 18085/42 and 11757/43. [Class 38 (v)] Subsidiary contacts such as 44, 46 cease to function in their normal manner when the main contacts 11, 4a of an electromagnetic switch become unduly worn. The electromagnetic switch has two core portions 35, 12 which move together against the respective actions of springs 38, 7, when the magnet is energized, the lower core 12 carrying a bridging contact 11 which engages the pivoted " fixed " contacts 4a, biassed by the springs 7, and the upper core operating a lever 41 which operates the auxiliary contacts 44, 46. In the form shown, when the magnet is energized, the contacts 44, 46 close a maintaining circuit for the magnet, but should the main contacts become worn, the final position of the core, after the two parts 35, 12 have come together, will be slightly different and the contacts 44, 46 will not close. Alternatively, Fig. 3 (not shown), the auxiliary contacts may be arranged normally to open an auxiliary circuit when the magnet is energized. In this case, when the main contacts are worn, this auxiliary circuit remains closed and a bimetal strip 30 is heated which after a time interval breaks the circuit of the electromagnet. Specification 560,871 is referred to.