6kV浆液循环泵电机定子绕组接地故障分析及预控

Analysis and Pre-control of Stator Winding Grounding Fault of 6 kV Slurry Circulating Pump Motor

某600 MW火电机组6 kV脱硫浆液循环泵电机在机组降负荷后短时升负荷时,带载热态启动过程中出现速断保护动作现象,测量电机绝缘电阻为零,更换备用电机运行。通过对电机解体,发现转子鼠笼端环焊块脱落、定子绕组外绝缘破损严重,确定绕组接地造成保护跳闸,从保护定值、运行操作、规程要求、检修维护多方面分析根本原因,提出工作票及运行规程优化建议,为预控此类故障提供参考思路。

There occurred activation of quick-break protection during the heat-status starting process with loading encountered by a 6 kV desulfurized slurry circulating pump motor in a 600 MW thermal unit when the generator was experiencing post-load-reduction short-time load increase.The measured motor insulation was zero,and the standby motor substituted for operation.After disassembling the motor,it was found that the welding blocks on end ring of squirrel cage disconnected and the external insulation of stator winding was seriously damaged.It was determined that the winding grounding caused protection activation.This paper analyzes origin of the fault from the aspects of protection setting,operation,regulation requirements,maintenance and repair,and puts forward suggestions for optimizing work orders and operation regulation,providing useful information for the pre-control of similar faults.