220kV变电站主变压器低压绕组熔断事故分析

Analysis on an Accident of Main Transformer Low Voltage Winding Fuse in 220kV Substation

某220 kV变电站主变压器发生一起低压绕组断线故障。针对主变压器重瓦斯保护首先动作,接着主变压器轻瓦斯保护发出信号的现场事故特征,对主变压器进行气相色谱分析试验;对变压器三侧直流电阻进行分试验、对故障前短路阻抗试验以及录波器波形进行分析,初步判断断线故障是由变压器内部U相绕组存在突发性高能量电弧放电造成。最后的变压器的解体试验验证了对主变压器故障性质、故障位置诊断分析的正确性,并提出了相应的改进措施与建议。

Low voltage winding disconnection of the main transformer occurred in one 220 kV substation. In allusion to ciaar- acteristics of field accident that heavy gas protection of the main transformer firstly acted and then light gas protection sent signal, gaseous phase chromatographic analysis experiment was conducted for the main transformer. Deduced from test on transformer three-side DC resistance, short-circuit impedance test before the fault and analysis on recorder wave form, the reason for disconnection fault was initially considered as sudden high energy arc discharge of U phase inside the transformer. Disassembly experiment on the transformer verified fault property and validity of diagnosis analysis on the fault position. Relevant improvement measures and suggestions were proposed.