| 摘要 |
PURPOSE:To enable to detect emergency ignition generated in four thyristors by a method wherein a light emitting diode to detect current flowing in breakover diodes is connected between DC terminals of rectifier bridges. CONSTITUTION:When P side is positive and an excess forward directional voltage is applied to the thyristor TH22 to be generated by unbalance of division of voltage between the thyristors TH21, TH22, a cathode current flows as diode D15 D11 resistor R13 breakover diode BOD1 D14 R12 D7 light emitting diode PD D10 TH21, and emergency ignition of the thyristor TH21 can be detected by radiation of the light emitting diode. When an excess forward directional voltage is applied to the thyristors TH21 and TH22 at the same time, by setting properly the values of the resistors R2, R3, the current in the light emitting diode comes not to zero to enable detection of emergency ignition. |
