几起主变保护动作原因分析

文中以3个案例介绍了主变差动保护动作(含瓦斯继电器动作)情况。详析差动保护动作后,根据动作报文信息和故障电流电压的波形、幅值及相位来判断差动保护动作的原因,确定故障相别,快速锁定故障点的位置,为检修部门查找故障点和准备修试提供方向;在主变空冲时,由于试验班对主变小修及预试后产生较大"剩磁",或者新型变压器使用铁心材料特性较"硬"的原因而导致主变在送电时差动保护动作,则应该向调度部门正确地解释差动保护动作原因,为尽早恢复主变运行提供关键的依据。

Analysis of Operation Causes of Main Transformer Protection

Operations of the diffevential protection of Main Transformer including gas relay are introduced by taking three cases as examples. Based on operation reports and the analysis of waveforms, amplitudes and phases of failure current and voltage, how to find operation causes, determine fault phases and lock the locations of fault points is analyzed in detail. This can help maintenance departments for fault points and be well prepared for repairments and tests. During the main transformer＇s empty rush and power supplying, the action of diffevential protection is caused by the residual flux generated by minor repairs and pre-test. The ＂hard＂ chracteristic of the iron cores of new type transformers is also the reason. The case should be explained accurately to the dispatching department to offer the key basis for transformer＇s operation as soon as oossible.