With an actual pillar insulator that is used in the real grid

a study has been carried out on the surface flashover characteristics of the insulator with lightning impulse at different gas pressure and electric field distribution. The curve of surface flashover characteristics as a function of nitrogen pressure is obtained. Three types of insulator shape were then designed and machined

including straight rode type

double shed type and four-shed type. With the calculation and simulation of the electric field distributions of these insulators

the influences of different shed shapes and electric field distribution on the surface flashover characteristics of insulators wer

e studied. Results show that the averaged 50% flashover voltages in both positive and negative polarity increase with gas pressure approximately linearly. As surface flashover is a significant factor which can cause potential breakdown in electrical equipment

findings for this study serve as a useful guidance for designing a robust insulation structure of low-pressure N

2

cubicle type gas insulated switchgear.