DC flashover mechanism in a rod/rod gap with clean and contaminated barrier

An investigation on the barrier effects under DC voltage was carried out in a 50 mm rod/rod electrode system with a clean, particle-contaminated barrier and a barrier with small hole. The results show that a clean barrier with certain diameter is very effective to increase DC flashover voltage of the gap. The highest flashover voltage of the gap with a barrier depends on the barrier´s diameter, position and dielectric strength. The flashover voltage can be slightly reduced by a conducting particle on the barrier surface. However, a small hole on the barrier results in strong decrease of the flashover voltage. In the paper, flashover characteristics of the rod-barrier-rod gap and the mechanism of barrier effects are discussed