PROCESS OF TESTING STATE OF THYRISTOR Russian patent published in 1995 - IPC

FIELD: electrical engineering. SUBSTANCE: process of testing state lies in forced unblanking of each thyristor when voltage across it reaches threshold value. Reference signal directly proportional to threshold value of voltage and to number of thyristors connected in series is formed. Reclosure signal directly proportional to voltage at which tested thyristors connected in series are unblanked forcefully is formed. Difference between reference and reclosure signals is formed and by malfunction signal formed with emergence of current through thyristors in the absence of control pulses this difference is transformed into number of inoperative thyristors. In this case reclosure signal can be formed by amplitude detection of voltage across thyristors connected in series or it can be formed in the form of commutation emf across thyristors with its subsequent conversion in direct proportion to damping ratio of recovery voltage. Commutation emf can be formed by holding of system voltage at moment of emergence of current through thyristors. EFFECT: improved authenticity of testing. 4 cl, 7 dwg