大电流互感器的电磁场影响及现场测试

Electromagnetic field effect and locale test of the large current transformer

针对大电流穿心CT的测试,为了降低试验的难度,普遍采用的是均绕等安匝法和二次测差法。但这两种测试方法并不能模拟现场实际工况。测试人员在使用这两种方法时,往往忽略工作现场电磁场环境对互感器误差的影响。对某750kV变电站的LW13-800kV罐式断路器中的CT进行误差测试,结果误差超差,后改变试验方案反复测试,发现外电磁场对互感器误差的影响很大。

In order to reduce the difficulties of the large current straight through current transformer （CT） test, commonly uses the uniformly winding equivalent ampere-turn method and secondary metering differential method. But these two methods can＇t simulate practical situation of locale, when using the two methods, the test personnel often neglect the effect of electromagnetic condition for CT error in work site. Makes error test for CT of LWI3-800kV pot type circuit breaker in 750kV substation, the error is out of the range, test repeatedly after change the test schemes, finds out that external electromagnetic field has great effect on CT error test.