On=off switching device for compensation capacitors - consists of two thyristors in antiparallel energised by control dependent on voltage difference

摘要

The capacitor of a compensating assembly has an ON and OFF switch consisting of two thyristors (1, 2) in anti-parallel, energisable by a control switching the thyristors on only when, on the ON command, the voltage difference between the mains voltage and capacitor voltage is approx zero. Pref. the control is an opto-triac (10) with a zero point switch. The ON command for the opto-triac may be mains voltage dependent. The command is supplied via an opto-coupler output transistor (21). Whose input is fed from the mains via a capacitor (3) and a bridge rectifier (19). ADVANTAGE - Low-cost design, reliable operation, and long service life.