OVERVOLTAGE PROTECTIVE CIRCUIT OF REACTIVE POWER COMPENSATING DEVICE

摘要

PURPOSE:To lower the dielectric strength of a thyristor switch and capacitor, by turning off the thyristor switch synchronously to a point of time when no overvoltage is impressed upon the capacitor when the thyristor switch is wrongly ignited. CONSTITUTION:When a thyristor switch 4 is wrongly ignited and an overcurrent flows, a comparator circuit 14 detects the overcurrent and sets a flip-flop 22 through an OR circuit 19. The output signal of the flip-flop 22 is inputted into a gate igniting signal generating circuit 28 through an OR circuit 26 and a gate igniting signal Sg is stopped. In case where a capacitor voltage VC exceeds an overvoltage level at the time when a capacitor current IC becomes zero, each output signal of comparator circuits 13a and 13b is inputted into the gate igniting signal generating circuit 28 and the gate igniting signal Sg is given to the thyristor 4. When such an arrangement is made, impression of an overvoltage upon the thyristor and capacitor can be prevented.