| 摘要 |
PURPOSE:To prevent the erroneous operation due to noise or the like and to reduce the gate loss of a thyristor by automatically applying a reverse bias when the thyristor is OFF, and further leaking charge to become the overvoltage source when turning ON and OFF. CONSTITUTION:When a switchgear is OFF, i.e., when thyristors 11 are OFF, a voltage divided by a resistor Rb(K-1) and BB(K-1) is applied between the gate and the cathode of a GTOK, thereby improving the noise resistance to prevent the erroneous operation. The resistor RB(K-1) operates also as a function of the leakage resistor of the overvoltage applied to the GTOK. When a switch ON command is inputted to the gate of the thyristor GTO1, thyristors GTO2-GTOK are sequentially turned ON. When a switch OFF command is inputted to the gate of the GTO1, the thyristors GTO2-GTOK are sequentially turned OFF. |
