Electro-optical measurment of pre-breakdown current in dielectric liquids

The electrical pre-breakdown current in dielectric liquids under non-uniform field with tungsten tip have been investigated using photo-optical measuing technique and nanosecond rectangular high voltage pulse generator. The streamer propagation velocity is deduced for each dielectrics from the relation curve of gap spacing vs. breakdown time lag. The dependences of the time lag on gap spacing, voltage and temperature are also investigated. The constant streamer propagation velocity between electrodes are unaffected by tip radius and gap spacing at a fixed applied voltage.