Patent GB-446790-A (GB)
Title: Improvements in means for automatically regulating an electrical quantity
IPC: G05F1/32
Filed: 1935-05-27
Abstract: 446,790. Automatic control systems; converting. ALLMANNA SVENSKA ELEKTRISKA AKTIEBOLAGET, Võsteras, Sweden. May 27, 1935, No. 15407. Convention date, May 28, 1934. [Classes 38 (ii) and 38 (iv)] Electromotive force, current.-In means for regulating an electrical quantity by the voltage drop in an inductance magnetized by a rectified current proportional to that in. the inductance and by a direct current independent of the alternating current but dependent on the regulated quantity the inductance, the alternating current in the same, and the rectified component are proportioned so that the inductance operates in a region of highest sensitivity to additional direct current magnetization. The amplitude of the A.C. magnetization is several times the value of H determined by the intersection of the saturation asymptote and the tangent to the magnetization curve at the point of maximum permeability, and the rectified ampere turns are made very nearly equal to the A.C. ampere turns. The inductance may incorporate a leakage path in a transformer influenced by the D.C. magnetization. It may consist of parallel windings adapted to prevent inductive coupling between A.C. and D.C. circuits. Fig. 1 shows an inductance 5 in the exciting circuit of a dynamoelectric machine 1 the voltage of which is maintained constant by a direct current saturating winding 8 connected across the dynamo terminals, the inductance having a rectified current winding 6 and a co-operating constant D.C. excitation 8 giving, with the current in the winding 5, the conditions described. Fig. 2 shows an arrangement for maintaining constant voltage on a load circuit connected in series with a regulating inductance 14 which is saturated as described by a winding 15, supplied by a current transformer 16 and rectifiers 17, and regulation is effected by a winding 18 supplied through rectifiers 23 from a transformer winding 22. This transformer has a limb 19, magnetized by rectified current in a winding 24 in the manner described, so that the induction in the limb 19 is sensitive to changes in the magnetization from a winding 26 excited in accordance with the difference between the load circuit voltage at the terminals 13 and a battery 27. The relay 31 is provided to prevent reversal of polarity of the limb 19. This risk may be avoided by using a glow discharge lamp in place of the battery. Fig. 4 shows a rectifier 44, supplying a constant current for battery charging or other purposes. Inductances 42, 43 control the current and these are variably saturated by a D.C. winding 45 carrying the exciting current of the rectifier. An inductance 48 in the exciting circuit of the rectifier is saturated by co-operating windings 46, 52 in accordance with the induction, the first carrying a rectified current proportional to that in the inductance 48 and the second a constant current, as from the battery 35 on charge ; the value of the inductance 48 is changed by the exciting winding 51 sensitively in accordance with variations in the rectifier output, so that the excitation current of the rectifier and the impedance of the inductances 42, 43 are simultaneously controlled.