| 摘要 |
PROBLEM TO BE SOLVED: To provide a power conversion device which can protect snubber circuits by allowing operations for a longer time when thyristors with overcurrent protection functions are self-extinguished due to a voltage beyond a breakover voltage, in the power conversion device in which the thyristors with overcurrent blocking protection functions are provided with the snubber circuits. SOLUTION: In the power conversion device 10 having a thyristor valve 2 in which the snubber circuits 22A, 22B and 22C are arranged at the VBO-free thyristors 21A, 21B and 21C connected in series, a counter 14 increments its count value when VBO extinction is detected, the counter 14 decrements its count value according to a pulse signal generated by a clock 13 while the VBO extinction is not detected. When the count value of the counter 14 becomes a value smaller than or equal to a set value NT, a protection device 4 is operated for protection. COPYRIGHT: (C)2011,JPO&INPIT
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