Abstract: A snubber circuit for a GTO thyristor including a series-connected member of a capacitor and a diode connected in parallel with a GTO thyristor and a series-connected member of a resistor and a thyristor connected in parallel with the diode. The thyristor is adapted to be turned on when the GTO thyristor is turned on and the thyristor is adapted to be turned off at the same time as or immediately after a turn off of the GTO thyristor, whereby the circuit is enabled to perform the same protecting function as that of a snubber circuit for a GTO thyristor which includes no thyristor and, further, to block a discharging current from the capacitor due to the ripple voltages produced across the GTO thyristor after its turn off, by means of the thyristor which is then in an off state, so that no current may flow through the resistor.

Abstract: This invention serves to reduce the drop of feeder voltage in an electric railway, and relates to a feeder voltage compensating apparatus for electric railways wherein an accumulator and a thyristor rectifier are connected by a thyristor switch circuit which can change-over the charging and discharging directions of the accumulator.