Effect of BTA on Charge Mobility in Insulating Oil and Oil-Immersed Paper

1,2,3 BTA) is a widely-used additive to limit the oil flow electrification in oil-paper insulation of HVAC transformers, but it is still indeterminate whether BTA is applicable to converter transformers. Our previous experiment shows that BTA promotes charge accumulation at the oil-paper interface under DC stress, and it cannot be explained by its effect on the electric double layer and the interface barrier. Considering that charge mobility is also an important factor that affects the interface charge characteristics, the effects of BTA on charge mobility in insulating oil and oil-immersed paper is investigated in this paper. The addition of BTA increases charge mobility in both insulating oil and oil-immersed paper, especially for positive charge, and it increases the charge mobility in insulating oil more significantly than in oil-immersed paper, widening the already huge mobility gap between insulating oil and oil-immersed paper, which causes the promoting effect of BTA on charge accumulation at the oil-paper interface. Reducing the disparity in charge mobility between insulating oil and oil-immersed paper is beatifical to suppress charge accumulation at the oil-paper interface.