Thyristor control circuit for gas discharge lamp - regulates trigger pulses according to requirements and prevents surge on current interruption

摘要

A circuit is used for the operation of high pressure vapour lamps using an ultra-violet layer applied by the drying of a lacquer layer. It uses a thyristor to regulate operation in accordance with power requirements so that the discharge is not quenched during no-voltage phases and it prevents excessive current surges after temporary interruption of the supply. An ohmic bridge resistance (5) is applied across the thyristor regulator unit (2) to maintain the discharge of the lamp (4) at minimum discharge and the thyristor adjustment alternating current is maintained at a constant operating value by means of a regulator (6) by alteration of the phase of the triggering pulses. On failure of the feed voltage the trigger pulses are fed at a phase with a minimum difference from the zero voltage point of the alternating voltage.