In order to further reveal the influences of barrier dimensions on the withstand voltage levels of gas insulated gaps

we experimentally investigated the AC withstand characteristics of air insulated rod-plane gaps before and after introducing the barriers of different dimensions.Moreover

by varying different barrier positions and gap distances

we investigated the barrier effects with different dimensions on the AC breakdown voltages and corona onset voltages

as well as the effects of the residual charges on barrier surfaces on the breakdown voltages.The results show that the breakdown voltage is significantly increased by the presence of a barrier.With a large barrier inserted

the breakdown voltage level is even increased up to about 2.32 times of that without a barrier.The corona onset voltage is slightly decreased under the effect of the barrier with a maximum decreased voltage about 2 k V.The residual charges on barrier surfaces always have no accumulative effect on the breakdown voltages.In order to achieve the best performances concerning to the global AC withstand characteristics

the effects of barrier dimensions and positions on the breakdown voltages and corona onset voltages should be synthetically considered.