| 摘要 |
PURPOSE:To protect an overcurrent rapidly with a simple structure by connecting a current detecting resistor in series with the cathode side of a GTO, and inserting a diode between the gate of a GTO turning OFF thyristor and the cathode of the GTO. CONSTITUTION:An overcurrent protecting circuit of a GTO1 omits an overcurrent detector, connects the first diode 31 between the cathode of the CTO1 and the gate of a thyristor 16, and connects the second diode 32 between a parallel circuit of a capacitor 15 and a resistor 14 provided at the collector of a transistor Q1 of a drive circuit 5' and the gate of the thyristor 16. Thus, when the detected voltage by a current detecting resistor 4 exceeds the prescribed value E4, the voltage is applied to the gate of the thyristor 15 directly through the first diode 31. Thus, the turning ON current is forcibly flowed irrespective of the control pulse signal output of a drive controller 9 to turn ON the thyristor 16 and to turn OFF the GTO1. |
