核电站500 kV GIS设备局部过热分析与处理

Analysis and Treatment of Local Overheating of 500 kV GIS Equipment in a Nuclear Power Plant

某核电站500 kV GIS(SF6气体绝缘全封闭式组合电器)在正常运行时发现其A/C相波纹管支架处出现热点,经过现场红外测温得知:A相热点温度高达167℃,C相热点温度约为82.3℃,B相无热点,温度约为50℃。通过分析设备的温度、工作电流、接地电流、红外成像等能反映设备过热类型的参数,逐个排除分析判断造成设备过热的原因。过热原因锁定为GIS壳体与波纹管材质不同,导磁率不同,磁路通过法兰密封面螺栓来分流,相对松动的螺杆导磁性能差,导通性好的螺杆就容易出现热点。经分析,在波纹管上下法兰之间增加短接铜排,可消除由波纹管材质不同、螺杆松紧程度不同而导致的热点问题。设备停电后加装导流短接铜排、更换波纹管热点法兰固定螺栓的同时,也对该设备进行解体检查,对局部过热点的密封圈进行更换。处理后设备正常运行,热点消失,A、B和C三相均保持在45℃左右,设备恢复正常,同时也验证了故障原因分析的正确性。

During normal operation,a hot spot was found at the A/C phase corrugated pipe support of a 500 kV GIS(SF6 gas insulated fully enclosed composite electrical device)in a nuclear power plant.After on-site infrared temperature measurement,it was found that the temperature of the A phase hot spot was as high as 167℃,the C phase hot spot was about 82.3℃,and the B phase had no hot spot,with a temperature of about 50℃.By analyzing the parameters such as temperature,working current,grounding current,and infrared imaging of the equipment that can reflect the type of equipment overheating,a step-by-step elimination method is used to analyze and determine the cause of equipment overheating.The final cause of overheating is identified as the difference in material and magnetic permeability between the GIS shell and corrugated pipe.The magnetic circuit is diverted through the flange sealing surface bolts,and relatively loose screws have poor magnetic conductivity.Screws with good conductivity are prone to hot spots.After analysis,adding a short copper bar between the upper and lower flanges of the corrugated pipe can eliminate the hot spot problems caused by different materials of the corrugated pipe and varying degrees of screw tightness.After the power outage,the equipment was equipped with a short copper busbar for diversion,and the fixing bolts of the corrugated pipe hot spot flange were replaced.At the same time,the equipment was disassembled and inspected,and the sealing ring of the local hot spot was replaced.After processing,the equipment ran normally,the hotspot disappeared,and the A/B/C three-phase remained at around 45℃.The equipment returned to normal,and the correctness of the fault cause analysis was also verified.