Detection of partial discharge in solid and liquid insulation with an electric field sensor

Partial discharges in high voltage insulation systems are often a precursor to dielectric breakdown. Detection of PD is thus an effective method to evaluate dielectric faults in the initial stage. Using an electric field sensor to detect PD was originally successfully developed to assess the condition of GIS. In this paper this technique is applied on solid insulation system and oil-impregnated system. PD signals are measured as individual pulses waveforms through a wide bandwidth measurement system by using an electric field sensor. Phase-resolved patterns obtained by the conventional PD detection method also are illustrated. The spectrum analysis shows electromagnetic waves with frequencies up to 1 GHz are emitted from partial discharge in the solid and liquid insulation system