GB394618A - Improvements in tap changing gear for electric transformers and the like - Google Patents

Abstract

394,618. Transformers. ENGLISH ELECTRIC CO., Ltd., 28, Kingsway, London, and CAMPBELL, I. D., 14, Queensville Avenue, Stafford. Feb. 17, 1933, No. 4942. [Classes 38 (ii) and 38 (iv).] Relates to transformers in which the voltage applied to a load circuit such as the primary of a boosting transformer 2 may be reduced from a maximum to zero, reversed, and then increased in the opposite sense by continuous movement in one direction of pairs of brushes 11, 12 operatively associated with a reversing switch 4 and with a pair of circuit breakers 7, 8 in the connections to a centre-tapped choke 6, the circuit breakers 7, 8 being adapted to relieve the brushes of current during tap-changing, and consists in the provision of contacts 13, 14 adapted to engage one or other of the brushes in the zero-voltage positions to short-circuit the choke 6 during movement of the reversing switch when one of the circuit breakers 7, 8 is open. The Figure shows the connections for one phase only of a three-phase arrangement, the brushes 11, 12 engaging successively contacts t1 .. t6 associated with tappings on the winding 1 to effect voltage change from a maximum to zero, and then, after operation of the switch 4 to connect the load circuit to the opposite end of the winding 1, passing on to co-operate with the contacts of the next phase, whilst another pair of brushes (shown in broken lines) proceed to engage the contacts t1 .. t6 to effect increase in voltage in the opposite sense.