6 kV磨煤机事故跳闸分析

Accident Tripping Analysis of 6 kV Pulverizer

针对某6 kV磨煤机在运行过程中正常启动且电流返回正常,紧接着BC相两次电流突变后电机三相短路速断保护动作开关跳闸事件,首先通过分析该磨煤机保护动作时序记录、保护动作相关曲线,初步判断故障原因为磨煤机电机内部短路;接着对磨煤机电机内部进行解体检查,确认雨水或雨停后的滴水从已锈蚀穿孔的电机冷却器顶板进入电机内部是电机运行中短路的直接原因;最后提出相应的防范措施。

A 6 kV coal pulverizer started normally and the current returned to normal during operation, and then the motor three-phase short-circuit quick break protection action switch tripped after two current mutations of phase BC. In view of this accident, first of all, by analyzing the protective action time sequence record and protective action related curve of the pulverizer, it was preliminarily determined that the fault was caused by the short circuit inside the pulverizer motor. Then, the inside of pulverizer motor was disassemble and inspected, and the direct cause of the short circuit in the motor operation was confirmed that the rain water or the dripping water after the rain stopped entered into the motor from the top plate of the rusted and perforated motor cooler. Finally, corresponding preventive measures were proposed.