The Impact Of Aging On Specific Surface Area Of Insulation Pressboard

Oil-paper insulation is very effective insulation system for large power transformers. The long-running process by electrical, thermal, mechanical, and other aging factors result in performance degradation of the insulation and it may eventually affect the system safety and stability of operation.The specific surface area (SSA) is an important physical parameter of the insulation pressboard, and has a significant effect on the moisture absorption of the paper. This paper prepared insulation pressboard with different aging degree through the method of accelerated thermal aging. Equivalent age time of this method is from 0 to 40 years. Furthermore, after studying oil removal methods of insulation pressboard, proposes and suggests use of ethanol as a solvent in oil pressboard standard procedure. SSA of insulation pressboard was measured by BET method.The results show that aging can reduce SSA of insulation pressboard, which will result decrease in decrease of its moisture absorption capability; Immersion oil will affect the measurement of the SSA which will decrease the SSA; The ultrasonic oscillation method for cleaning oil-cellulose sample five times, samples containing transformer oil can be reduced to an ideal low level state, then cleaned, the changes in the content of the value are small, can be neglected.