GB611707A - Improvements in and relating to electronic valve circuits for interchanging power between alternating and direct current circuits - Google Patents

Abstract

611,707. Converting. BRITISH THOMSONHOUSTON CO., Ltd. Nov. 22, 1943, No. 19497. Convention date, Nov. 23, 1942. [Class 38 (ii)] . In a converting arrangement comprising valves 22, 23 having cathode-immersed ignition electrodes 26 and arc pick-up electrodes 27 connected to a common excitation circuit 28, the latter is adapted to provide ignition impulses of short duration followed by a voltage wave of smaller amplitude but extending over a substantial part of the positive portion of the anode-cathode cycle. The arc is thus maintained at the electrodes 27 to an extent which permits of regulation of the converter by phase-adjustable voltages applied to grids 27a. The excitation circuit comprises two transformers 36, 38, the primaries of which are energized from different phases of the supply network 12, one of them through a wavedistorting network 33, 34, whereby its associated secondaries 39, 40 are caused to produce sharp voltage peaks, whilst the other produces phase displaced sinusoidal voltages in its associated secondaries 41, 42 which are respectively connected in series with the secondaries 39, 40.