High frequency transformer is favorable to boost the efficiency of transporting electricity

but it leads tocritical challenge to insulation system inside. To investigate the partial discharge characteristics of defects in oil-pa-per insulation systems under high-frequency voltage

a platform for partial discharge test is established

in which acolumn-plate model is adopted to simulate the surface discharge defect. Tests under high-frequencies of 10 k Hz

20 k Hz and 30 k Hz and power frequency of 50 Hz are set up

where constant voltages are applied. The experimentalimages are recorded by video camera

partial discharge signals by Rogowski coil. Characteristics of partial dischargeand dissolved gas production under different frequencies are compared and analyzed. Conclusions can be drawn thatthe partial discharge inception voltages of partial discharge signals under high-frequency voltage are much lower thanthat of power-frequency voltage

whereas the content of key gases especially H2 are boosted

indicating that the oil-pressboard insulation especially insulating oil are deteriorated more severely. Also

the partial discharge signals cen-ter on the time when the polarity changes resulting from the effect of space charge. Meanwhile

the discharge phaserange under high frequencies are wider than that under power frequency. Lastly

the du/dt and the effective time de-lay are affected by the frequency

thus

the average amplitude and times of partial discharge（PD）appear a peak val-ue around 20 k Hz in a single period.