| 摘要 |
PURPOSE:To provide a starting method for obtaining gate power at the turning OFF time from a main circuit by providing a switch between the cathode of an SCR and a load, operating the OFF gate of the SCR at the time of opening the switch to establish the charging voltage of the capacitor and operating the ON gate of the SCR. CONSTITUTION:A static induction SCR 1 is provided between a main power source 2 and a load 4, and a switch SW 3 is added between the cathode K of the SCR 1 and the load 4. In case of starting a DC switch circuit, a switch 3 is closed in the state that the SW 3 is opened. Then, the SCR 1 is conducted, and the voltage difference at both terminals of the SW 14 becomes equal to the power source voltage. Then, when the SCR 13 is turned ON, the capacitor 10 is charged. When the snubber capacitor 5 and the capacitor 10 are completely charged, the SCR 13 is naturally extinguished. Even if the SW 14 is further closed, the SCR 1 blocks the forward voltage. Accordingly, the load 4 is not energized. When the SCR 12 is conducted to discharge the capacitor 10, the load current will flow. |
