Trigger circuit for thyristor shunting mechanical switch - has gate coupled via rectifier to transformer whose primary is in series with switch

摘要

The trigger circuit, for a thyristor whose load is shunted by a series circuit of a transformer primary winding and a mechanical switch, consists of the saturating transformer (5) whose primary is in series with the switch (2) and whose secondary is connected via a rectifier to the thyristor's gate. If two thyristors are connected in antiparallel then two secondaries and two rectifiers are present. Alternatively the single thyristor may be replaced by a single triac. - The rectifier consists of a bridge connection of four diodes connected at one end via a series resistor (8) to the gate and at the other to the cathode of the thyristor. The gate-cathode circuit is shunted by a capacitor (7).