GB426271A - Improvements in and relating to voltage regulating systems - Google Patents

Abstract

426,271. Automatic regulation; thermionic valve circuits. BRITISH THOMSON - HOUSTON CO., Ltd., Crown House, Aldwych, London, HOLLAND, W. R., Redlynch, Bilton, and FORSTER, E. W., 101, Grosvenor Road, both in Rugby. Oct. 3, 1933, No. 27182. [Class 38 (iv)] [See also Group XL] In a system for automatically regulating the voltage of a generator, any departure from the predetermined voltage causes a mirror carried by a galvanometer or similar instrument to reflect a beam of light on to a photo-electric cell, 9 or 14, to cause a corresponding variation in the phase of the grid voltage of one or more mercury vapour valves 34, 36 through which the field 37 of the generator or its exciter is supplied. When the generator voltage exceeds the normal value, light shines on cell 9 and the grid potential of valve 10 rises above the negative value to which it is normally set by adjuster 5, causing valve 10 to conduct and energize relay 12 which then opens to insert resistance 21 in the bridge circuit 21, 22, 23, 24 thereby altering the phase of the voltage across the grid transformer 28, 29, 25 fed from the auxiliary A.C. circuit 38. This alteration in phase causes reduction of the current in field 37 with consequent reduction of the generator voltage. Reduction of the generator voltage below normal causes illumination of cell 14 and energization of relay 18 which short circuits 22 and causes such a phase shift of the grid voltage of valves 34, 36 as to increase the current through the field 37. A single photo-electric cell or a " split cathode " cell may be used. The Provisional Specification also describes an arrangement in which the galvanometer and photo-electric cell are replaced by a sensitive relay provided with contacts operating on a bridge circuit in which the A.C. potential may be balanced against a constant potential difference the relay being energized when the bridge is unbalanced.