Patent GB-407300-A (GB)
Title: Improvements in and relating to electric amplifying methods and means for use in regulating systems
IPC: H02P9/26
Filed: 1932-06-06
Abstract: 407,300. Automatic regulation. DUBILIER CONDENSER CO. (1925), Ltd., Victoria Road, North Acton, London.- (Assignees of Verman, L. C., and Richards, L. A. ; Rockefeller Hall, Itahaca, New York, U.S.A.) June 6, 1932, No. 15935. Void [Abridged as open to inspection under Sect. 91 of the Acts, June 6, 1932]. [Class 38 (iv).] Means for maintaining a physical condition, e.g. the voltage of an electrical circuit, at a predetermined value comprise a control element responsive to the condition, an amplifying device for impulses produced by the control element, and means responsive to the amplified impulses for maintaining the physical condition at the predetermined value. In one arrangement, Fig. 2, for maintaining constant voltage in a direct current circuit 6, 7 supplied by a generator 5, the difference between the potential drop across a resistance 8 connected across the circuit and the voltage of a battery 10 is impressed on the grid circuit of a thermionic valve 12, the output of which is amplified in a second valve 16 connected to the field winding 18 of an exciter 20 supplying the field 35 of the generator 5. The potentials of the various electrodes of the valves are obtained by tappings from a potentiometer 21, and the filaments are heated through transformers 31, 32 connected to an alternating current supply 33 which also controls a motor 34 driving the exciter 20. Fig. 3 shows a modified arrangement for maintaining constant voltage in an alternating current circuit 41 supplied from a generator 45. In this arrangement, two amplifying valves 49, 50 are provided, and the control valve 48 is operated at a low filament temperature and high plate voltage. Under these conditions, the current through the coupling resistance 64 between the plate of the valve 48 and the grid of valve 49 is nearly independent of the plate voltage but changes rapidly with the filament temperatures. The filaments of the valves are supplied with heating currents from the circuit 41 through transformers, and the filament temperature of the valve 48 is the controlling factor. The output of the valve 50 is applied to the field 42 of an exciter 43 which supplies the field 44 of the generator 45. The grid bias and plate voltages of the valves are obtained from taps on a resistance 47 supplied from the circuit 41 through a rectifier and filter system. Hunting is prevented by providing a feed-back coupling system, comprising a condenser 61 and a resistance 62, which reacts on the grid of the valve 48. The generator may be given a flat or rising voltage characteristic with increasing load by making the filament current in the control valve dependent on the voltage, current and power factor in the line. In the arrangement shown in Fig. 4, the filament 66 of the control valve 67 is supplied with a voltage derived from the line voltage through a stepdown transformer 68 and a potentiometer 71 connected across the line. The filament is also supplied with a voltage dependent on the line current through a variable resistance 75 and variable inductance 74 connected across a resistance 72 in the line. The operation of this arrangement is explained with the aid of vector diagrams. In a modification, the trans. former is connected in the line and the resistance across it.