GB1140612A - Improvements in electric circuit breakers - Google Patents

Abstract

1,140,612. Automatic circuit breakers; gas blast switches; electromagnetic switches. GENERAL ELECTRIC CO. 19 May, 1966 [21 May, 1965], No. 22345/66. Heading H1N. An overload circuit breaker is provided with separable contacts 15, 16, 17 adjacent to a passage interconnecting an arc initiation chamber 63 and an arc extinction chamber 64, the walls of these chambers evolving hydrogen under the influence of the arc. The side walls 67 and the back wall 65 of the chambers are preferably of polyoxymethylene which produces hydrogen without free carbon. The chambers are sealed except for vents 67B and the gas produced consequently drives the arc rapidly towards a plurality of parallel copper or brass splitter plates 68. The movable contact 17 is mounted on a shaft 45 attached to the armature 46 of an electromagnet 50 which directly moves the contact 17 to the open position upon overload. The shaft 45 is connected to contact 17 and to armature 46 by lost motion devices 57, 60 and carries a cam member 44. A handle 30 moves, through an overcentre spring 47, a pair of spring blades 40 whose ends 43 normally engage with a groove 44A in member 44 to move it between the open and closed positions. When the shaft 45 is moved by the electromagnet its rapid movement disengages the blades 40 from member 44 and it moves to the open position without moving handle 30. The blades 40 subsequently contract around shaft 45 (Fig. 3, not shown) to prevent the contact rebounding to the closed position. In series with the contacts and the coil 24 of the electromagnet are a pair of blowout coils 18, 21 associated with cylindrical cores 69, 70 and Y-shaped polepieces 72 aligned with arc runners 15A, 16A in the arc extinguishing chamber. The handle 30 may be replaced by a power operating mechanism.