Improvements in or relating to the protection of electro-magnetic circuits, particularly in dynamo electric machines

摘要

511,956. Dynamo-electric machines. GILL, B. Feb. 25, 1938. No. 6046. Drawings to Specification. [Class 35] [Also in Group XXXVII] In an electro-magnetic circuit, for example, in a dyhamo-electric machine comprising insulated conductors and a magnetic core, pole-piece &c. associated therewith and having a heat-responsive switch located in close proximity to the conductors, together with a relay controlled by the switch to break the circuit upon a predetermined rise in temperature, the heat responsive switch comprises heat-operated contacts located inside a sealed evacuated container. The invention is especially adapted for the protection of a motor of less than 7¢ horsepower, particularly a fractional horse-power motor. The heat-responsive switch may comprise a bimetallic strip. A number of series-connected switches may be provided, situated at danger points in the circuit to be protected.