关键词: 雷击事故, 电弧放电, 绕组变形, 断股

Abstract: As for the lightning outage of the phase-B winding of a 500 kV main transformer in a substation of CSG(China Southern Grid), this paper was aimed at finding the reason of the accident. According to the analysis of the test data, there seemed to have a series of fault phenomenon of arc discharges, turn-to-turn short circuit, deformation and even broken-wires in windings. In the disintegration process of the transformer when it was returned to the factory, some factors like free carbon and winding deformation were founded, which verified the initial conclusion from the data analysis. The causes of the accident turned out to be the electromagnetic vibration, which made the paper insulation worn out by the winding block. As a result, the insulation was broken down due to the thunder electric wave invasion, then the inter-tern short circuit fault was induced. In the end of the paper, the anti-accident measures were presented.

Key words: lightning outage, arc discharge, winding deformation, turn-to-turn short circuit