电动机差动保护误动事故的分析

分析了一起母线失电后快切装置动作时电动机起动过程中差动保护的误动事故。根据电动机首末端两侧电流波形及现场的实际情况,指出电流互感器饱和是导致这次事故的直接原因。分析了微机电动机保护装置在此次事故中的动作情况,并使用EMTP仿真工具仿真电动机在自起动过程中的电流波形。针对差动保护和电流互感器的特点,给出了避免因电流互感器饱和导致差动保护误动的措施和对策。

Analysis of Malfunction Fault of Motor Differential Protection

In course of motor starting after no-voltage bus, a malfunction fault of motor differential protection was analyzed. According to the current waveform and actual condition of the motor at two sides of the terminal, it is pointed out that the transformer saturation is the direct reason of causing this fault. The operation condition of motor microcomputer-based protection was analyzed in this fault, and the current waveform in the course of starting was simulated using EMTP simulation tool. According to the characteristics of differential protection and current transformer, the countermeasures were given to avoid differential protection malfunction caused by current transformer saturation.