Control of high pressure vapour discharge lamp current - uses measurement of current directly in front of lamp with thyristor control unit regulated accordingly

摘要

The vapour lamp emits ultra-violet radiation. Current flowing through a thyristor control unit is controlled by phase shifting. A minimum current necessary to maintain discharge in the lamp flows in parallel to the control unit, and in case of supply voltage failure ignition pulses are applied at a minimum distance from the a.c. voltage zero crossing. Lamp supply current is detected through a transformer directly before the lamp, and the thyristor control unit is regulated in accordance with the lamp current intensity.