GB542181A - Improvements in or relating to electric translating devices embodying thermal protective apparatus - Google Patents

Abstract

542,181. Protective cut-out arrangements. WESTINGHOUSE ELECTRIC INTERNATIONAL CO. July 15, 1940, No. 11704. Convention date, July 13, 1939. [Class 38 (v)] A translating device, such as a motor having a running winding 34 and a starting winding 32 which is controlled by a centrifugal switch 33, is controlled by a thermostat 20 in the form of a bimetal disc mounted on the end bell 14 by means of a plate 26, and subject to a single-loop, bare-wire, radiant heater 24 and to a heat-storage coil 22 of insulated wire non-inductively wound into a compact mass and thermally insulated from the end bell by a disc 30 of felt-like material or "Micarta" (Registered Trade Mark). In Fig. 3 the coil 22 is in the starting-winding circuit so as to cause the thermostat 20 to quickly open the circuit 8 in the event of overloaded starting conditions or stalled rotor, the mass of the coil being such that the circuit is held open for a prolonged period of, say, three to five minutes. In modifications, however, it can be connected in the running-winding circuit, or in the main circuit so as to respond to starting and running conditions, Figs. 4, 5 (not shown). In a further form, Figs. 7, 8 (not shown), the coil 22 is inserted between two halves of the starting winding and carried on that winding, the thermostat being also located on the winding- side of plate 26. In Fig. 6 (not shown) a modified supporting arrangement is illustrated for the coil and thermostat, and the latter is included in the circuit itself so as to be directly heated. Where the coil 22 is in the running or main circuit, the continuous heating tends to accelerate tripping, but is counter-acted by raising the opening temperature of the thermostat or changing the resistance of heater 24.