GB450885A - Improvements relating to arc-suppressing arrangements for alternating current electric switches - Google Patents

Abstract

450,885. Arc-rupturing in switches. ANDERSON, J., 137, Aldridge Road, Perry Barr, Birmingham. Feb. 7, 1935, No. 3954. [Class 38 (v)] An arrangement for suppressing arcing in A.C. switches comprises a motor g rotating synchronously with the current and driving a commutator f having a slip ring a and two half-rings b, c interconnected at d, e. The ring a is connected by means of a brush m to the movable switch member j, and the members b, c are connected to the fixed contacts h, i through brushes k, l, the arrangement being such that the trailing ends of b, c are under the brushes at current-zero of the cycle. In operation, suppose that when j separates from h, i, the segment b is under the brush k, then an arc is only formed between i, j. At the first zero, the commutator circuit shunting the break h, j is broken arclessly at b, k, and the arc between i, j is put out by the short-circuiting thereof by the segment c coming under the brush l. A similar action occurs if the arc is formed between h, j. For polyphase working, the above arrangement is repeated for the various contacts. A more perfect break can be obtained by providing short segments b<1>, c<1> connected by rectifiers n, o to the segments b, c which are shortened slightly at the trailing end so that at current zero, the brushes bridge both segments. The rectifiers prevent current flowing from the additional segment to the brush.