750kV变电站罐式断路器合闸电阻片失效分析

Analysis on a Closing Resistor Failure of Tank Circuit Breaker in a 750 kV Substation

针对某750 kV变电站罐式断路器合闸电阻片出现的磨损、裂纹等故障,通过对故障合闸电阻片进行宏微观形貌检查、X射线检测、SEM和EDS检测分析,结果表明:一方面,由于部分合闸电阻支架端部压板存在间隙、叠装不紧密,单只接触面受力不均匀,局部区域压力超限,造成磨损、裂纹等故障;另一方面,因电阻片与金属支架或相邻电阻片局部接触,接触部位电流密度和温升增大,产生局部温差应力,造成电阻片局部开裂和镀铝层起皮脱落。对优化罐式断路器合闸电阻结构设计方面、表面平整度及喷层厚度提出意见和建议,以避免同类故障的发生。

In allusion to the wear,cracks and other faults of the closing resistor of a tank circuit breaker in a 750 kV substation,the analyses based on the macro and micro morphology inspection,X-ray inspection,SEM and EDS inspection of the fault closing resistor show that on the one hand,due to the gap at the end pressing plate of some closing resistor supports and the stacking is not tight,the force on a single contact surface is uneven,and the pressure in local areas exceeds the limit,resulting in wear cracks and other faults;on the other hand,due to the local contact between the resistor and the metal support or adjacent resistor,the current density and temperature rise at the contact part increases,resulting in local temperature difference stress,causing local cracking of the resistor as well as peeling and falling off of the aluminum coating.Opinions and suggestions are put forward on optimizing the structural design,surface flatness and spray layer thickness of the closing resistance of the tank circuit breaker so as to avoid the occurrence of similar faults.