GB601996A - Improvements in and relating to compensated electro-thermal relays - Google Patents

Abstract

601,996. Thermal switches. SOC. A R.L. ETABLISSEMENTSBRESSON. June 19, 1945, No. 15618. Convention date, June 9, 1943. [Class 38 (v)] A compensated thermal relay, especially for temporarily locking out a circuit-breaker which has opened as a result of a, short-circuit, comprises an operative Y-shaped bimetallic strip B carrying the main current, a compensating bimetallic strip C, and a third bimetallic strip A which is heated by radiation from strip B. The strips A, B, insulatingly carry co-operating contacts a, b<2> in the circuit of the circuitbreaker closing coil. The strip B also carries a contact b<1> co-operating with a contact c on strip C which is arranged at an angle to strip B to prevent radiation effects, Fig. 2 (not shown). The contacts a, b<2> are normally closed and contacts b<1>, c normally open, but on overload, strip B bends faster than A and contacts a, b<2> separate while contacts b<1>, c close to energize a relay to open the circuit-breaker. When the overload ceases and thermal equilibrium is re-established, b<1>, c open and a, b<2> reclose allowing the closing coil to be energized.