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Ferromagnetic Resonance Caused By Saturation Of Electromagnetic Potential Transformer
May 25, 2018

The operation experience shows that the ferromagnetic resonance overvoltage caused by the iron core saturation of the electromagnetic voltage transformer has occurred in the 3 220KV power grid of the neutral point insulation and neutral point through the arc suppression coil (but the possibility of temporary disengagement of the arc suppression coil) and the neutral point direct grounding (but the possibility of temporary disconnection) in the neutral point. . For example, a 220Kv substation in Jiangsu has caused the resonant overvoltage of the transformer due to the neutral point temporarily ungrounded, and the four grounding system of a 154KV in the Northeast Power Grid has caused the resonant overvoltage of the transformer due to the temporary isolation of the arc suppression coil, and the neutral insulation system of a power plant in Jilin province. The resonant overvoltage of the transformer has been aroused many times. The 6KV neutral point ungrounded power plant system of a power plant in Shandong province has also experienced the ferroresonance overvoltage caused by electromagnetic potential transformer. A more frequent occurrence in a neutral distribution network is an internal overvoltage that causes the most accidents, because other grounding systems are likely to occur only when they become neutral point edge systems.

When the overvoltage occurs, the excitation current of the winding is greatly increased due to the saturation of the core of the transformer, which can reach more than 100 times the rated excitation current, which causes the fuse of the transformer, the fuel injection, the burning of the winding and even the explosion. In some cases, the overvoltage may be very high (maximum). The insulation flashover or the lightning arrester exploded for about 3 times the phase voltage. In addition, there will be an illusory grounding when the overvoltage occurs, in fact there is no grounding in the power grid. This causes a missense to the operating staff. In short, when such overvoltage occurs, it will pose a great threat to the safe operation of the power grid.


Add: No.38 South Taoyuan Road, Yaozhuang Town,Jiashan County, Jiaxing City, Zhejiang Province, China
Contact person: Elva Zhuang&Sunny Ni
Tel:+86-573-84775555
Fax:+86-573-84776699
Phone:+86-13732570078
E-mail:sales9@great-relay.com
       sunny.ni@great-relay.com