Space Charge Distribution Characteristics of Pressboard Modified by Nano-TiO2 at Different Temperature Gradients

Since the converter transformer has complex operating conditions, the charge accumulation is easy to occur on the oil/paper interface, which leads to insulation failure. The space charge is one of vital factors, which affects the electrical performance of oil/paper insulation system. In order to measure the space charge, the pulsed electro-acoustic (PEA) method is used in this paper, and the distribution characteristics of space charge for the pressboard modified by nano-TiO
2
are analyzed at disparate temperature gradients. In addition, the influence mechanism on temperature for space charge distribution of oil-pressboard modified by nano-TiO
2
is discussed. It is found that the temperature gradient can result in the space charge distribution by increasing the mobility of different carriers. The results show that the hetero-charge accumulate more at the low temperature side (at bottom electrode) because of the temperature gradient, while at the high temperature side (at top electrode) only a small amount of homo-charge accumulates. The insulating pressboards modified by nano-TiO
2
can effectively suppress the space charge accumulation behaviors.