目前,我国部分大中型水轮发电机的灭磁系统,采用灭磁开关配合 ZnO 非线性电阻的灭磁方案,其原理如图1所示。SCR 表示励磁整流柜,U_d 是其输出的整流电压,FMK 是双断口灭磁开关,R_f 是 ZnO 非线性电阻器,D 是正向阻断二极管。正常运行时,FMK 合上,励磁电压 U_L 正压,R_f 上没有电流。灭磁时,FMK 跳闸并在其断口建立弧电压 U_k。根据灭磁时 At present, the demagnetization system of some large and medium-sized hydroelectric generators in China adopts the demagnetization scheme with the demagnetizing switch and the ZnO non-linear resistance, and the principle is shown in FIG. 1. SCR said the excitation rectifier cabinet, U_d is the output of the rectifier voltage, FMK is a double-break demagnetization switch, R_f ZnO non-linear resistor, D is the forward blocking diode. Normal operation, FMK closed, the excitation voltage U_L positive pressure, R_f no current. When de-excitation, FMK trips and establishes arc voltage U_k at its fracture. According to de-excitation