Identifying short-circuited controllable semiconductor component in mains-commutated bridge circuit - triggering components irrespective of normal triggering sequence with delayed pulses and evaluating fault currents

摘要

The method involves shifting the position of the main pulse towards rectifier operation until a fault current is detectable. Irrespective of the normal sequence of component switching, a selected component is triggered with a single pulse with a delay angle such that output is not caused if there is a short. The main current is measured and if no fault current is detected a component in the next phase arm of the bridge is triggered. If a fault current is detected it is stored and the opposite polarity component in the same arm triggered. The fault is located by comparing the measured error current with the previously measured one. ADVANTAGE - Eliminates blowing of fuses and enables triggering of controlled semiconducting components, e.g. thyristors, irrespective of their normal switching sequence.