Study of the surface discharge on the air-insulation interface

Surface partial discharges may degrade the electrical insulation in time, so they are destructive to material. For the measurement of surface partial discharges (PD) it was used a needle-cylinder electrode configuration and the analyses were done using the phase-resolved partial measurement and pulse-sequence. The surface PDs were spread between the zero cross and the peak of applied voltage. The effect of surface charge and the surface discharge events for various insulation materials were analyzed by PDs patterns, too. The corona discharge was observed when the needle tip was distant from surface insulation.