Protection circuit power stages of electrified railway - has voltage limiter shunting inductor of LC input filter

摘要

The protection circuit, for use in power stages whose supply volts are apt to return suddenly, e.g. current collector jumping an electric locomotive, gap in power rail, has a voltage limiter (5), e.g. a Zener diode, in parallel with a capacitor (7). The capacitor is shunted by a resistor (8) and is in series with a diode (6) across the inductor (2) of the input filter. The avalanche voltage of the Zener diode is slightly greater than the admissible voltage fluctuation at the buffer capacitor (3) and is designed to handle the energy stored in the inductor in the worst case. The voltage limiter may also be a voltage-dependent resistor.