GB422565A - Improvements in and relating to electric converting circuits - Google Patents

Abstract

422,565. Converting. BRITISH THOMSON - HOUSTON CO., Ltd., Crown House, Aldwych, London. - (Assignees of Palmer, H. L. ; Toll Street, Scotia, New York, U.S.A.) July 13, 1933, No. 19850. Convention date, July 13, 1932. [Class 38 (ii)] An electric powerconvertingarrangement comprises an arc discharge device 12 having a control grid and a control circuit for the grid including an inductance device 16, a resistor 13 and a transformer 14 supplied with current from the A.C. source 11 so the grid potential is in phase opposition to the anode. The presence of the reactance device, however, by its inductive effect delays the instant at which the grid periodically becomes negative until the anode becomes positive, thereby rendering the discharge device conductive. In response to any predetermined condition, switch means 18 closes its contacts 19 to short circuit the secondary winding of the reactive device 16 and changes the phase of the grid control to bring the grid and anode potentials into exact phase opposition and render the discharge device non-conductive. When the load 10 is inductive, a negative bias is applied to the grid circuit by means of a capacitor 23 and leak 24. In a modification, (not shown), the inductance reactive device is replaced by a capacitance and resistance in parallel, the switch device interrupting the resistance circuit and introducing the capacitance to neutralize the inductance in the grid circuit.