Qin Kai

The discovery and analysis of suspended discharge defects in TV

Reducing the influences of suspended discharge on insulating property can improve power supply reliability. In this Paper, through analyzing an explosion accident of 220kV SF6 gas-insulated electromagnetic voltage transformer (TV), it shown that the primary cause of the accident is attributed to the suspended discharge in the internal equipment, resulting in a reducing performance of SF6 gas-insulation. Under the low lightning overvoltage, short circuit of TVs primary lead over the ground is caused. Meanwhile, the experiment verifies that the suspended discharge causes instable electrical connection in internal equipment, resulting in fluctuation of TVs secondary terminal voltage and misjudge of equipment insulation online monitoring. At last, the paper proposes the countermeasures and recommendations on preventing from suspended discharge in internal electrical equipment.