Toward understanding the characteristics of water tree propagation under DC voltage polarities

To understand the influence of DC voltage polarity on propagation of water trees, a water tree accelerated aging experiment was performed on XLPE sheet specimens under four rectified voltages using KCl solution and distilled water. An optical microscope was used to observe water tree morphology and measure water tree length of the specimens after 22-day aging experiment. The experimental results show that the morphology and length of water trees are strongly dependent on DC voltage polarity. As a result, a possible mechanism is proposed to explain the propagation characteristics of water trees under different DC voltage polarities.