Experimental research on minimum approach distances and complex gaps for live working in substation

Live working in substation is of importance to ensure the reliability of power system. Minimum approach distance and complex gaps are key parameters for safety of workers and electric equipment in substation. The discharge characteristic curves corresponding to four live working gap configuration in substation, such as "equalpotential personnel-grounding structures", "equipotential personnel-adjacent phase bus", "live phase bus-working personnel-grounding structures", "live phase bus-working personnel-adjacent phase bus" were obtained by the switching impulse discharge test in this article. Combined with overvoltage level of 220 kV typical substation design scheme, the minimum live working electrical minimum approach distances were calculated : phase to ground safe distance 1.2 m, phase to phase safe distance 2.1 m, and a safe distance, phase to ground complex gaps 1.3 m, phase to phase complex gaps 2.2 m. The minimum approach distances comply with relevant regulations for 220 kV substation live working by comparative analysis.