Charge storage and transport in oil-impregnated pressboard at polarity reversal under HVDC

Abstract

Space charge plays an important role in the breakdown and conduction processes of a high voltage direct current (HVDC) insulation system. Electrical breakdown due to charge accumulation in transformer oil and pressboard can cause failures of power transformers, especially at DC polarity reversal. In this paper, we focus our attention on the charge accumulation and movement in an transformer-oil-impregnated pressboard under DC polarity reversal at 60/spl deg/C. Using a pressure wave propagation (PWP) technique, the distribution of space charge in the sample was measured both at stationary and transient conditions.