Thyristor pulse control circuits

摘要

A thyristor pulse control circuit has a main thyristor, a commutation circuit including a commutating capacitor, and a bypass contactor connected across the main thyristor, and is provided with apparatus for applying a gating signal to the main thyristor immediately before the contacts of the bypass contactor close and also immediately before the contacts of the bypass contactor close to prevent arcing at the contacts. The application of the gating signal is inhibited if a comparison of the voltage across the commutating capacitor with the load current flowing immediately before the bypass contactor closes indicates that the load current is too great to be safely commutated by the commutating capacitor at the measured voltage.