GB603327A - Improvements in or relating to automatic electric voltage regulation - Google Patents

Abstract

603,327. Automatic voltage control systems. COURSEY, P. R., STEATITE & PORCELAIN PRODUCTS, Ltd., and DUBILIER CONDENSER CO. (1925), Ltd. Nov. 9, 1945, No. 30002. [Class 38 (iv)] In an automatic voltage regulating system, changes in the capacity of a condenser, having a ceramic dielectric based upon titanium compounds, subject to the voltage to be controlled, actuates means correcting voltage deviation. In Fig. 4 a voltage-sensitive condenser 10 is connected to bus-bars 17, 18 of a D.C. generator 19, the voltage of which is to be controlled. This condenser also forms, with an inductance 11, a tuned circuit in the grid circuit of a triode valve oscillator 12. Deviation of generator voltage from a desired value alters the oscillator frequency and a contact-making frequency meter 21 energizes a relay 26 or 30 according to the sense of the deviation to operate a D.C. shunt motor 34 in the appropriate direction to correct the generator voltage by adjustment of a field rheostat 36. A variable condenser 25 serves for setting the desired generator voltage. The following modifications of this arrangement are referred to :- (a) motor 34 adjusting tap connections to the generator field ; (b) an auxiliary valve oscillator providing a reference frequency and the frequency meter responding to the beat frequency of the two oscillators to permit the use of higher oscillator frequency; (c) in the case of A.C. voltage control, connection of the voltage-sensitive condenser to the bus-bars through a transformer and rectifier, and adjustment of an induction regulator or transformer tap changer by motor 34. In Fig. 5, the D.C. voltage to be controlled 44 is applied to a voltage-sensitive condenser 40 in one arm of a normally balanced A.C. bridge supplied from a constant voltage auxiliary A.C. source 45 of any convenient frequency. Deviation of the controlled voltage from a desired value results in an output from the bridge which is rectified as shown and applied to a polarised two-way relay 51 controlling correcting means as in Fig. 4. Alternatively, a pair of directional relays may be energized from or form part of the bridge. The bridge may be normally unbalanced and its output amplified electronically. Source 45 may be an A.C. voltage to be controlled and the output of the bridge may control the grids of gas discharge-type valves directly connected in the A.C. circuit. Thermal insulation or thermostatic control to minimise the effect of temperature variations on the voltagesensitive condensers is referred to. In cases where A.C. is applied to the condensers the use of D.C. bias as a means for selecting a sensitive working point is referred to. Specifications 574,577 and 601,109, [both in Group XXXVI], are referred to.