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Measurement of transient enclosure voltage in a 220kV gas insulated substation

Transient enclosure voltage (TEV) is a special case of very fast transient over-voltages, which generate during switching of disconnector in gas insulated substation (GIS). It would cause insulation problems such as spark discharge between the flanges, and interference to secondary equipment due to high-frequency electromagnetic radiation. Many studies have been done to investigate TEV above 420kV, but no special results at lower voltage levels. In this paper, we have found the discharge phenomenon between the insulating flanges near current transformer caused by TEV, when switching unloaded short busbar in a 220kV substation. The unique design of insulating flanges leads to the significant discharge through measuring and analyzing the voltage of GIS enclosure. This result may help to understand the TEV mechanism and be aware of insulation design in lower voltage levels.