GB190906A - Improvements in or relating to thermally operated circuit controllers - Google Patents

Abstract

190,906. Igranic Electric Co., Ltd., (Cutler-Hammer Manufacturing Co.). Dec. 20, 1921. Mercury switches. -A thermal overload circuit-breaker which closes a circuit when the abnormal current has been flowing for a certain time, the circuit being again automatically broken when the excess current is reduced, consists of an evacuated or gas-charged glass container with mercury contact pockets 6, 7 in a barrel portion 4, and an extension 5 containing mercury, part of which is ejected into the barrel to bridge the contact pockets when excess current flows in the heating coil 15. When the excess current is reduced, the mercury cools and flows back into the extension, thereby breaking the circuit, the diameter of a restricted portion 8 determining the time-element of the interruption. An independently variable time-element for the establishment of the circuit is provided by the size of the heating coil and by the thermal capacity of the two-part casing 16, 17 which encloses the heating element and the extension, and carries clip contacts 22, 23 to engage cap contacts in connection with the electrodes. Reference is made to Specification 173,657.