Measurements of the charge of streamers propagating along transformer oil-solid interfaces

This paper presents an experimental study of the positive streamer charge in transformer oil and oil-solid interfaces in a point-plane gap (5mm) under impulse voltage 50ns1800μs (maximum peak voltage 24 kV). The experiment is intended to compare the charge of streamers propagating in transformer oil with and without a solid barrier along their path. The solid barrier constricting the streamer volume consists of two parallel strips of either impregnated pressboard or a polymeric film (PA6) installed at both sides of the point electrode. The maximum cumulative charge of the streamer is found for the case when the impregnated pressboard is used and the minimum cumulative charge for the case of the polymer as a barrier.