Single Partial Discharge in Nonuniform Electric Field for Different Polymer Dielectrics

The first single partial discharges under ramp voltage are investigated in submillimetric air gaps and nonuniform field. Several polymer films with different thicknesses are used as a dielectric barrier: 12- and 100-mu m polyethylene terephthalate films, 28-mu m polyimide film, 6- and 12-mu m polypropylene films. The inception voltage (breakdown voltage) and the discharge current are registered. The parameters of the accumulated surface charges measured by a rotating capacitive probe are presented. The surface charge patterns obtained by means of the dust figure method are shown. Probable mechanisms of the discharge development are discussed.