Abstract:

Abstract: Taken Fangshan 35kV transformer substation accident for example, the paper analyzes firstly single-phase ground fault of non-grounded neutral system because of rainfall and the decrease of cable head dielectric strength, and further analyzes that the accident spread is closely related to the power grid operation mode, excessive capacitive current and intermittent arc grounding over-voltage. Then some measures to limit similar accidents are proposed and some suggestions are given finally.

Key words: Key words: non-grounded neutral system, single-phase ground fault, capacitive current, arc grounding over-voltage