GB481774A - Improvements in or relating to thermostatically operated relays - Google Patents

Abstract

481,774. Thermal switches. GENERAL ELECTRIC CO., Ltd., and BARTLETT, H. E. Dec. 28, 1936, No. 35496. [Class 38 (v)] Energization of one or other of two heating windings controlling two bimetallic strips 41, 42 causes the rocking of an arm 44 into the other of its two positions, the movement of a bowed spring 45 over dead centres to retain the arm in its new positions, the opening or closing of a main circuit, the opening of auxiliary contacts to break the circuit of the heating winding and the closing of auxiliary contacts to prepare the circuit of the other heating winding so that when this is energized later on, the relay will be operated back into its original position. The arm 44 carries a member (not shown) which moves between two stops on the pivoted carrier of a mercury switch 52 controlled by a second dead-centre spring. The mercury switch is a two-way one and serves to control both the main and auxiliary circuits, Fig. 3 (not shown). In a modification, Fig. 2 (not shown), the arm 44 carries directly a mercury switch controlling the main circuit and operates spring contacts arranged on either side of it for controlling the auxiliary circuits. The heating windings may be energized by rectified intermittent carrier currents of suitable frequency, Fig. 1 (not shown).