A 66kV transformer insulation breakdown accident analysis and prevention measures

The total reflection of the wave will occur twice and the lightning over-voltage will be increased by 2 times when the lightning wave along the line reached in the disconnect switch are derived through the analysis of the accident 66kV transformer insulation breakdown. This will lead to the switch breakdown and discharge to be grounded. In this case the breaker is between the arrester and the transformer and the transformer will withstand 2 times arrester residual voltage result in the transformer breakdown. Finally, effective preventive measures combined with the practical experience are proposed.