| 摘要 |
PURPOSE:To improve the detection sensitivity of a rare short-circuit and to simplify a circuit constitution by combining the increase of a primary-side current and the reduction of the supply voltage of an auxiliary power source and detecting the abnormality of rare short-circuit at the time of the occurrence of rare short-circuit in a high voltage oil. CONSTITUTION:Since an input power source holds only a limited current capacity, the output voltage EB of the input power source 36 is reduced by several to several tens % when a primary-side current IB is increased by the rare short- circuit. An auxiliary voltage generated by an auxiliary voltage generating coil 45 is reduced in proportion to the reduction of a collector pulse voltage, and as the result, a sensitivity raising voltage EO applied to the gate side of a thyristor 34 is reduced. Therefore, the subtraction quantity of the voltage between the gate and the cathode of the thyristor 34 is reduced and a detection voltage IBR1 applied between the gate and the cathode is quickly increased. Consequently, a voltage VGK between the gate and the cathode is more quickly increased, and the detection sensitivity of rare short is effectively raised. |
