GB758729A - Improvements in and relating to electrical control circuits - Google Patents

Abstract

758,729. Rectifying. BRITISH THOMSONHOUSTON CO., Ltd. Oct. 25, 1954 [Nov. 5, 1953], No. 30667/53. Class 38 (2). The D.C. through an inductive load LF supplied from A.C. source S is controlled by a rectifier-switch combination V in parallel with the load, a capacitor C being connected in the supply. The rectifier-switch combination may be any rectifying arrangement wherein the flow of current may be initiated by a signal at a chosen instant during the conducting half-cycle. It may comprise a valve V, the control signal being applied to grid G, or a dry-plate rectifier having in series a transductor, Fig. 5 (not shown). When the signal, which may be the error signal of a control system, is such as to allow a D.C. component in the load LF, which may be a generator field coil, the capacitor C is charged when the rectifier conducts so that in the halfcycle when the rectifier is non-conducting the voltage applied to the load is the sum of the capacitor and supply voltages. The voltage across the load is initially large and falls as the current builds up. This arrangement gives an increased rate of response of output current to changes in the applied signal. Where the load current may be required to flow both ways two rectifier-switch combinations may be connected in reverse-parallel. The supply circuit may include inductance L and resistance R.