In liquid insulation under sinusoidal applied voltage, discharges occur around the peak of the cycles. The occurrence of PD and its magnitude is strongly dependent with applied voltage. A main characteristic of PD is its stochastics properties that dependent on early electron appearance. Number of discharges also dependent on applied voltage. Energetic discharges around the peak can disrupt large bubbles where PD occur then forming smaller bubbles where PD activity can be inhibited due to the increase of inception voltage.