An overvoltage protection device for thyristor valve

摘要

A thyristor valve protected from an overvoltage by means of an arrester, comprising a voltage detector (DET) for detecting a forward voltage (FV) applied to the thyristor valve (1) and generating an output signal when the detected voltage exceeds a predetermined voltage (Vp*) which is set lower than the protection level of the arrester, and a circuit (40) for inhibiting a gate pulse from being applied to the thyristor valve (1) in response to the output signal from the voltage detector (DET). The inhibition circuit (40) permits the gate pulse to be applied to the thyristor only when the condition of the presence of conduction command signal PHS and forward voltage signal FV, and the absence of output signal Vp* of the voltage detector, is satisfied.