GB496811A - Improvements in methods of regulating vapour arc converters - Google Patents

Abstract

496,811. Converting. GENERAL ELECTRIC CO., Ltd., and DUNHAM, C. R. May 1, 1937, No. 12508. [Class 38 (ii)] Comprises a converting arrangement employing discharge devices wherein control of the moment of ignition is effected in dependence on the balance of a number of magnitudes as expressed by the equation a Cos B - bI - c= O, in which B is the angle of delay of the ignition, I is the load current, and a, b, c are constants. A further magnitude may be included proportional to the rate of change of current. In the form shown in Fig. 1, each grid of a discharge device 3 operating as a rectifier receives impulses from a transformer 15 when current flows through an auxiliary rectifier 13. The circuit of the rectifier 13 includes a voltage from the transformer 16 proportional to a Cos B, and voltages in opposition, from 18 proportional to the rate of change of load current, from 17 proportional to load current, and a constant voltage from 19 which may be varied to adjust the output voltage of the arrangement. When these voltages balance an impulse of current flows through the primary of the transformer 15. A further voltage across the condenser 21 proportional to the difference between the output voltage of the arrangement and a standard voltage 22 may be included in circuit. A construction of device 17 for obtaining a direct current proportional to the load current is described in the Specification. This consists of an A.C. supply in series with a choke and a rectifier, the choke being variably saturated by the load current so that the rectifier output varied in proportion to the load current. A mechanical arrangement for controlling a phase shifting transformer 55 for supply of grid potentials is shown in Fig. 3. A sliding arm 51 moved by a torque motor 53 exerts by means of the lever 46 a clockwise torque on the spindle 40 proportional to the term a Cos B. In addition, anticlockwise torques proportional to the current and rate of change of current, and constant torque by means of a weight 44 and pulley 45 are exerted on the spindle 40. The system moves to a position of equilibrium at which these torques balance and in doing so adjusts the phase shifting transformer 55 which supplies the grid potentials. Additional adjustments may be effected by moving the stator of the phase shifting transformer by means of a motor 57.