GB595665A - Improvements relating to inductive windings - Google Patents

Abstract

595,665. Exciting dynamo - electric machines; modifying reactive characteristics of electric circuits. ENGLISH ELECTRIC CO., Ltd., and SHAW, N. H. July 11, 1945, No. 19764/46. Divided out of 595,660. [Classes 35 and 38 (iv)] [Also in Group XXXVII] Direct-current circuits containing inductive windings are arranged to provide time-constants which differ from the natural time-constants of the inductive windings. A bridge comprises two sections of an inductive winding arranged in opposite arms, and two resistors arranged in the other opposite arms. A direct-current generator supplies two opposite terminals of the bridge and a field winding of the generator is excited according to the voltage between the other two terminals. The invention is shown as applied to the field windings of a Ward- Leonard generator 2 supplying a direct-current motor 1. The generator field winding is divided into two equal sections 34 and 35 which are arranged as the opposite arms of a bridge, the other arms of which consist of resistors 36 and 37 having equal resistance-values with the sections 34 and 35. An exciter 3 supplies bridge terminals E and F and an auxiliary exciter field winding 38 is energized from terminals G and H. Under steady current conditions the bridge is balanced, but when a potentiometer 25 is adjusted to increase or decrease the generator field excitation, the bridge becomes unbalanced due to the time lag of the coils 34 and 35, and a current is passed through the winding 38 in such a, direction as to change the excitation of the machine to accelerate the change of current in the windings 34 and 35. Switching means may be inserted between the bridge terminals G and H. A rectifier may be placed in series with the auxiliary field winding. Alternatively, the field winding may be connected to the unidirectional output terminals of a bridge rectifier, the input terminals of which are connected to the terminals G and H. Adjustable resistors may be connected in adjacent arms of the bridge rectifier. Specifications 528,789, 594,951 and 595,660 are referred to. '