| 摘要 |
PURPOSE:To realiably protect a GTO thyristor against a damage by shortcircuiting the secondary winding of an OFF-gate transformer when a load current reaches the value larger than the turning OFF capacity of the thyristor. CONSTITUTION:An node current of a GTO thyristor 7 is detected by a current transformer 9, and a current proportional to the anode current of the thyristor 9 is flowed to a load resistor 55. When the anode current of the thyristor 7 becomes larger than the turning OFF capacity, a thyristor 11 is fired, and the OFF gate pulse is not applied to the gate of the GTO7 even if the OFF gate pulse is applied to an OFF gate transformer 2. Accordingly, the thyristor 7 interrupts the anode current larger than the turning OFF capacity. |
