No-voltage switch for unchopped half-waves or wave trains - has capacitor charged by control voltage or impressed current

摘要

The no-voltage switch has a capacitor discharged during zero crossings, and the capacitor discharge surge is amplified by a transistor which controls a thyristor or a triac. The capacitor (3) is discharged through a switching transistor (4) controlled by mains voltage through a voltage divider consisting of a resistor (6) and a Zener diode (7). The voltage pulse arising at the resistor (5) when the capacitor (3) discharges is amplified with the help of a transistor (10). The impulse is added to the potential of the thyristor to be regulated (14) by means of the separating transformer (13). The negative half wave, released after a zero condition of the mains voltage, flows from the thyristor (14) to the resistor (15).