GB599407A - Improvements in or relating to automatic circuit-breakers - Google Patents

Abstract

599,407. Automatic circuit - breakers. THEUNISSEN, F. J. M. Sept. 19,1945, No. 24286. Convention date, April 23, 1940. [Class 38(v)] An automatic circuit-breaker comprises a release coil 9, the armature or armatures of which are adapted on overload to trip the breaker and to act directly on the movable contact 2 independently of the tripping mechanism. On a moderate overload, a bimetallic strip 8 acts on arm 10 of the pawl 7, thereby releasing a lever 5 which is moved counter-clockwise by a spring 4 until the centre-line of the spring moves past pivot 3a of the movable contact 2 which is then snapped open. If a heavy overload occurs immediately, the armature 11 moves upwards and trips the pawl 7 through an extension 14, Fig. 1, and, on a short-circuit, the armature 11 moves a non-magnetic plunger 12 to open positively the circuit. In Fig. 2, a heavy overload causes an auxiliary armature 15 to move downwards to trip the breaker through lever 17, and a short-circuit causes tripping and also causes the plunger 12, carrying the main armature 11, to open the circuit. In a modification, Fig. 3 (not shown), the lever 17 is replaced by a sliding rod which is acted upon by a conical armature to release the pawl.