Lifetime evaluation of medium and small size power transformers part 2: Experimental study

This paper is the experimental verification of the theoretical analysis in Part 1 of a new method to evaluate the lifetime of power transformers. A new experimental method is proposed to detect the degree of polymerization (D
p
) values during the paper aging process. Experiments show that the aging process of insulating paper is related to the temperature, the oxygen and the water content. If the oxygen and the water content are low, the D
p
value decreases logarithmically with time. At the same temperature level, D
p
values are submitted to normal distribution. Applying the presented methodology, expected lifetime of new type of power transformer SBS9 is evaluated.