| 摘要 |
PURPOSE:To obtain an inexpensive safety apparatus at the time of the breakage of a switching element to be tested, by a method wherein a rectification diode and a small capacity diode are connected in reverse parallel relation to each other while the switching element to be tested is connected in series to the former. CONSTITUTION:Rectification diodes SR1, SR2 connected to thyristors T5, T6 to be tested in series have current capacities equal to or more than that of the thyristors T5, T6 and small capacity diodes SR2, SR4 are connected to SR1, SR2 in reverse parallel relation to each other. At first, when an overcurrent circuit breaker B is interposed and a trigger pulse is applied to the gates of the thyristors T1-T6, a full-wave rectificatiin wave form is developed in load and a regular voltage wave form is applied to the thyristors T5, T6 to be tested as a load test. If either one of T5, T6 are broken, a power source E is shortcircuited through T1-T4 and SR2 or SR4 but SR2, SR4 are cut by melting because of small capacity and come to an open state to secure safety. In addition, because the power source is not shortcircuited by the rectification diodes, the repairing of the test circuit can be also carried out inexpensively. |
