Through the series circuit null serial reactor

摘要

PROBLEM TO BE SOLVED: To provide an inexpensive series circuit equipped with an overvoltage protection functions, by providing a monitoring means which detects a thyristor equipped with an overvoltage protection function being ignited by overvoltage thereby preventing the enlargement of a snubber circuit or an insulator.;SOLUTION: This series circuit is composed of a plurality of thyristors 11 with an overvoltage protection functions which are connected in series through a series reactor 17, a gate control means for each thyristor 11 with an overvoltage protection function, a forward voltage detecting circuit 16 which detects the voltage between the main electrodes of each thyristor 11 with an overvoltage protection function, and a monitoring means which monitors the operation of each thyristor 11 with an overvoltage protection function, according to the detection value of this forward voltage detecting circuit 16. The above monitoring means judges that the thyristor with an overvoltage protection function concerned is self-excited by the detection value of the above forward voltage detecting circuit 16 being at or over a specified value after passage of a specified time since supply of each gate signal from the gate control means.;COPYRIGHT: (C)2005,JPO&NCIPI