Patent GB-400206-A (GB)
Title: Improvements in and relating to electric regulators
IPC: G05F1/26
Filed: 1932-04-16
Abstract: 400,206. Automatic regulation. BRITISH THOMSON-HOUSTON CO., Ltd., Crown House, Aldwych, London.-(Assignees of Fitzgerald, A. S. ; Warwick Road, Wynnewood, Pennsylvania, U.S.A.) April 16, 1932, No. 10953. Convention date, April 17, 1931. [Class 38 (iv).] An arrangement for automatically regulating the voltage of a circuit 10 through a booster transformer 12 comprises valves 14, 15 for deriving direct current from the supply circuit 11, through a transformer 13, other valves 19, 20 for inverting the direct current to alternating current for energizing the booster transformer, and means responsive to the voltage across the circuit 10 for controlling the phase relations of the valves 19, 20. In the arrangement shown in Fig. 1, the control grids of the valves 19, 20 are excited from a transformer 22 connected to an impedance phase-shifting circuit comprising a transformer 24, connected across the supply circuit 11, a resistor 25 and a saturable reactor 26, the saturating winding 27 of the reactor being energized from the transformer 24 through a valve 28. The grid of the valve 28 is excited with the potential across a condenser 29, which is preferably provided with a discharge resistor 30. The potential of the condenser is varied in accordance with variations in the voltage of the circuit 10 by means of a voltage responsive bridge 31 having two pairs of opposite arms 32, 33 with dissimilar current-resistance characteristics, the unbalance voltage of the bridge being applied to the condenser 29 through a transformer 34 and valve 35. The bridge 31 is normally unbalanced, and maintains on the condenser 29 a negative potential of such a value that the valve 28 supplies the correct excitation to the saturating winding 27 for maintaining the desired phase relations in the grid potentials of the valves 19, 20. Variations in the voltage of the circuit 10 increase or decrease the unbalance of the bridge to bring about the necessary corrections through variations in the potential applied to the condenser 29. In a modification, Fig. 2, the condenser 29 is charged from the circuit 10 through a transformer 38 and valve 39, the grid of which is excited from the unbalance voltage of the bridge 31 through a transformer 34 and negative bias battery 40. In this arrangement the voltage of the circuit 10 is rapidly varied between upper and lower limits, and the unbalance voltage of the bridge reverses polarity when the voltage of the circuit 10 passes through the normal value. The valve 39 is conducting during the period when the voltage is above its normal value, and the negative charge on the condenser 29 is then increased, with a resulting decrease in the conductivity of the valve 28, which in turn lowers the voltage of the circuit 10 through the boosting transformer. When the voltage of the circuit 10 has fallen below its normal value, the unbalance voltage of the bridge is reversed, the valve 39 becomes non-conducting, and the condenser 29 discharges through the resistance 30, until the increased conductivity of the valve 28 again raises the voltage of the circuit 10. In a further modification, Fig. 3, the bridge 31 remains balanced as long as the voltage of the circuit 10 is normal, but any variation from the normal upsets the balance of the bridge in one or the other direction, the unbalanced voltage being applied to control the charging of the condenser 29 through one of a pair of valves 41, 42 reversely connected in parallel. Specification 219,026, [Class 38 (ii), Electric currents, Converting &c.], is referred to.