Relationship Between VHF Signals and Discharge Magnitude of Partial Discharge from Needle Plate Electrode

In order to explore the relationship between very-high frequency(VHF) signals and apparent discharge magnitude with needle-plate electrodes within different air-gap distance,the VHF method combined with pulse current(IEC 60270)in partial discharge(PD) was used.A linear relationship between peak to peak voltage of VHF signals and apparent discharge magnitude was obtained,and quadratic relationship between cumulative energy from VHF signals and apparent discharge magnitude was also obtained.It was proved that calibration on PD measurement using high-frequency method could be solved theoretically and practically.On the premise of severe non-uniform electric field,the longer the distance of the air-gap is,the lower PD magnitude will be,when the voltage is close to breakdown,as the development of the discharge will be hindered by existing space charge.The theoretical derivation agrees with experimental results.