Switching of primary winding of power transformer with secondary connected to thyristor-converter - is timed to coincide with zero voltage across switch, by integrator controlling three=phase current regulator with matching transformer

摘要

The sec. side of the power transformer (2) feeds a thyristor-converter (3) fired by an ignition pulse stage (9) with stored program control (6), delivering e.g. 60 kA at 600 V to a DC output line (14). The prim. side is connected to the mains (12) by a medium-voltage power switch (1) pulsed from the same control. While the thyristor firing is inhibited, a three-phase AC regulator (7) is switched (8) to the sec. side and run-up by an integrator (10) to a limit corresp. to the full magnetising current. The control (6) is reset if a voltage-measuring relay (4) reports no zero within 1.5 seconds. USE/ADVANTAGE - For power supply to e.g. an electrolytic furnace, reaction-free switching is possible without expensive installations on the h.v. side of the power transformer.