中压开关柜微机保护装置误指示故障分析

Fault Analysis on Wrong Indication of Microcomputer Protector Used in Medium-Voltage Switch Cabinet

分析了两起中压开关柜内微机保护装置误指示的故障情况,确定引起故障的原因在于整流桥的泄漏电流超过了正常范围,提出在合闸回路前串接断路器常闭辅助触点,采用专用直流线路板,将发光二极管串接到微机保护装置的分合闸监视回路中等措施来避免此类故障发生。

Analysis was made to two fault cases of wrong indication situation of the microcomputer protector used m the mediumvoltage switch cabinet, determining that the cause for fault was that the leakage currents of rectifying bridge was beyond normal range. This paper proposed that normally closed auxiliary contact of the circuit-breaker was connected in series before closing circuit. Special DC circuit boards were adopted to connect light emitting diodes in series with making and breaking monitoring circuits of the microcomputer protector, to avoid such kind of fault from taking place.