GB691339A - Improvements relating to apparatus for the control of voltage and like regulators - Google Patents

Abstract

691,339. Automatic voltage control systems. WESTINGHOUSE BRAKE & SIGNAL CO., Ltd., and KING, K. G. Nov. 30, 1951 [Feb. 9, 1951], No. 3198/51. Class 38 (iv). In a system for automatically controlling an electrical variable, two D.C. relays are each positively biased to a position at which a negative bias causes the relay to assume the alternative position at which the negative bias is reduced at a controlled rate, the negative bias of one relay being increased and that of the other reduced in accordance with the magnitude and sense of deviation of the variable. As applied to the regulation of a direct voltage, Fig. 1, polarized relays 1, 2 are positively biased by windings 14, 17 energized from a D.C. source 20 to move their contacts from the positions shown. Resultant closure of contacts 3, 4 energizes from a D.C. source 25 negative biasing windings 15, 18 the effect of which is sufficient to return the contacts to the position shown. The next operation of the relays is then delayed until a condenser 21, associated with windings 15, 18, discharges sufficiently to reduce the negative bias. When the voltage to be controlled has the desired value, repeated simultaneous operation of contacts 5, 6 thus takesplace with no effect on relays 10, 11. When a voltage deviation occurs, however, an error signal is applied to windings 16, 19 which bias the relays in opposite senses so that one or other of contacts 5, 6 picks up before the other in the cycle to energize relay 10 or 11 to run an A.C. servomotor 7 in the appropriate direction to correct the voltage. In one modification positive bias of the relays is produced by a permanent magnet. In another modification the multi-winding relays are replaced by singlewinding relays supplied through rectifiers from the output of magnetic amplifiers each having three control windings to which positive bias, negative bias and error signal are respectively applied. Specification 623,661 is referred to.