| 摘要 |
PURPOSE:To prevent the malfunction due to dV/dt surely, by providing a transient current detecting circuit using an active element and by making input and output terminals of this circuit bidirectional in dielectric strength and operation. CONSTITUTION:If a positive or negative rapid potential fluctuation occurs in a main terminal 6a or 6b when a thyristor 9 is not operated, the transient current is flowed through a route of the main terminal 6a and a transistor 12 and drives a transistor 10 and reaches the main terminal 6b. At this time, the transient current is amplified by a transistor 12 of a transient current detecting circuit and becomes a larger current. As the result, the voltage between the gate and the cathode of the thyristor 9 is clamped at the voltage between the collector and the emitter of the transistor 10, thereby preventing the malfunction of the thyristor. |
