GB360843A - Improvements in and relating to overload thermally-operating circuit breakers - Google Patents

Abstract

360,843. Automatic circuit-breakers ; electromagnetic switches; switches partly electromagnetic. INTERNATIONAL GENERAL ELECTRIC CO., Inc., 120, Broadway, New York, U.S.A.-(Assignees of Allgemeine Elektricitats-Ges. ; '2, Friedrich Karl-Ufer, Berlin.) July 11, 1930, No. 21062. Convention date, July 11, 1929. [Class 38 (v).] A circuit - breaker or switch, which responds to overload and in some modifications to underload and which may also be moved " on " and " off " by hand or by remote control, comprises a bimetallic strip 1, which carries a contact 2 engaging a contact 4, and a dead-centre spring 8, which is fixed to the strip 1 at its one end and may have its other end movable. The strip I is V-shaped and carries the current, and upon a moderate continued overload moves to the right, the counter contact 4, which is mounted on a spring 6, and may also be influenced by an adjustable spring 9, following it till it strikes a stop 5, and the contact 2 then continuing to move so as to break the circuit under the influence of the spring 8 which has moved over the deadcentre. The parts may be so adjusted that when the bimetallic strip cools down, its tendency to return to the left overcomes the spring 8 and the switch closes again. To give a quick release on a sudden large overload, the strip 6 is of magnetic material or carries an armature 11 adapted to be attracted by an electromagnet 14 in the circuit, and the magnet 14 may have additional polepieces 27 adapted to attract a pivoted armature 21, the lower movable end of which is fixed to the lower end of the spring 8. The switch may also be opened or closed at any time by moving the armature 21 and thereby the spring 8 to the right or to the left either hy hand or by energizing one of two coils 23, 22. In the latter case, the energizing circuit of the coil 22 or 23 may be broken automatically by the opening movement of the contact 4 opening auxiliary contacts 38, 39, Fig. 4, the contact 4 moving in a recess 34 and creating a wind which passes through gaps 40 in the sides of the recess and blows out any arc at the contacts 38, 39. Also, in order to make the movement very sensitive, a spring may be arranged to act on the armature 21 so as nearly to balance the force on it due to the spring 8 in the closed position of the switch. The switch may also be adapted for underload response by letting a no-volt coil such as the coil 22 act on the armature 21 in opposition to a spring. The contacts 2, 4 are provided with silver insertions 3 and have electrodes 5, 15 to take the arc which is blown out by polepieces 16 energized by the coil 14.