GB554209A - Improvements in voltage regulating equipment - Google Patents

Abstract

554,209. Automatic control systems for electricity supply. STANDARD TELEPHONES & CABLES, Ltd., and TARR, J. E. March 28, 1942, No. 4178. Convention date, Oct. 19, 1940. [Class 38 (iv)] Voltage.-To avoid excessive voltage on a load circuit 7 supplied through a series connected regulating triode 8 and having a direct heated cathode, particularly when the source is a thermionic rectifier 3 having also direct heated cathodes and supplying as load an amplifier with indirectly heated cathodes, the grid 9 of the triode is biased almost to cut-off during the warming up period of an indirectly heated control tube 10. A potential divider, comprising a high resistance 17, relatively low resistances 18, 19 and a gas discharge tube 15 or other constant voltage device, is connected across the supply, either on the source or load side of the regulating tube, and the grid 9 and the anode of the control tube 10 are connected through a resistance 16 to the junction of resistances 17, 18 so that the potential drop in the resistance 17 ensures a fixed potential on the grid 9 sufficient to render the tube 8 substantially non-conducting and so prevent excessive voltage on the load circuit. A diode 20 with an indirectly heated cathode is connected across the resistance 17 and heats up in the same time as the cathode of the tube 10, producing an increasing current at resistances 18, 19 which raises the potential of the grid 9 to its normal operating value. Normal plate voltage is also applied to the tube 10 and the regulation proceeds in the normal way according to the setting of the potentiometer. Any suitable delay device may replace the diode 20.