GB412433A - Improvements in and relating to exciting circuits for dynamo electric machines - Google Patents

Abstract

412,433. Automatic regulation; control of D.C. motors. BRITISH THOMSONHOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Allgemeine Elektricitats- Ges. ; 2, Friedrich Karl-Ufer, Berlin.) Aug. 3, 1933, No. 21866. Convention date, Aug. 3, 1932. [Class 38 (iv).] Varying E . M . F .-The excitation d of a generator a in a Ward-Leonard system is supplied from A.C. mains R.S.T. through one of two grid controlled discharge tubes n1, n2 selectively rendered operative by a switch g for forward or reverse operation and whose grid voltages are obtained from a phase shifting circuit i1, m1, or i2, m2 controlled by a discharge tube n1 or n2 whose conductivity is controlled by the armature voltage of the generator. The phase shifting circuits are arranged on the primary sides of the transformers k1, k2 supplying the grid to control A.C. voltages for the valves h1, h2 and comprise a resistance m1, m2 in series with one branch l1, l2 of the transformer windings which are energized from the three-phase supply. The discharge tube n1 or n2 byepasses the resistance m1 or m2 in response to the armature voltage of the generator a and causes variation in the phase of the A.C. supplied to the grid of the valve h1 or h2 with respect to its anode voltage so as to vary the excitation of the generator a. The arrangement operates automatically during starting and running. Additional discharge tubes such as h1 and h2 may be provided to give full wave rectification of the exciting current. The resistances m1, m2 may be inductive resistances and may be regulable so as to provide several degrees of control.