GB700340A - Improvements in and relating to electric regulators - Google Patents

Abstract

700,340. Automatic voltage control systems. BRITISH THOMSON-HOUSTON CO., Ltd. March 27, 1946 [March 31, 1945], No. 9428/46. Class 38 (4) In a regulator for use with a load circuit including, in parallel, a resistive path and an impedance path having a negative impedancevoltage characteristic, a substantially constant voltage is connected in series with a second voltage across the output terminals and the latter is varied inversely with variations, of the current in the impedance path, from a predetermined value. The grid of tube 33 is connected to a point on the potential divider comprising resistances 26, 27, 22, 23, 132, 133, 134 while its cathode is maintained at constant potential by a voltage source connected across leads 24, 25. After initial setting any change in the potential of this grid relative to the cathode, caused by a corresponding variation of voltage across the resistive load 1, changes the anode potential of valve 33, which change is amplified in valve 34 and applied to the grid of valve 17 so that its impedance changes to restore the voltage across load 1 to its correct value. The present invention provides a further regulator 50 for varying the load voltage in accordance with the current conditions in that part of the load which is represented by the non- linear impedances 48, 49. The current supply from transformer 52 and rectifier 53 is stabilized by gas discharge tubes 59, 60 and appropriate voltages are taken from potential dividers connected across leads 54, 55, and a stabilized reference voltage is produced across resistor 65. Current from the load impedances 48, 49 is passed through resistors 111, 112 and 113, 114 but does not influence the steady current through 65 as it is counterbalanced by the shunt circuit through tube 60 and valve 66, whose impedance is changed to accommodate it by having the potential of the point 118, relative to 110, applied to its control grid. The potential of each point 48', 49' is communicated through resistors 125, 126 to the 'grids of valves 93, 90 which have a common cathode resistor 104 so that only the valve having the highest grid potential passes current, thereby influencing the current through double diode 83 to vary the grid potential of amplifier 75 and so change the potential of the point 74. This potential consequently changes in dependence on the greater current flowing in the two paths 48, 49 and by correspondingly changing the potential of the junction of resistors 22, 23 it causes adjustment of the load voltage in accordance with the current flow. The regulator 50 is rendered ineffective by setting the switch 129 to " off " so that the conditions in valve 75 remain steady and voltage control is effected only by the regulator 7. Fig. 3 (not shown) shows an extension of the embodiment in Fig. 1 in which the voltage is controlled in accordance with the highest current in four load paths instead of two.