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April 26, 2019
The aging mechanism of insulating material and factors influencing aging of oil-immersed power transformer are summarized,characteristics of aging mechanism in the courses of thermal aging,electrical aging,mechanical stress and multi- stress aging are concluded.
In the long-term operation of transformer, insulation aging will be caused by electric field, moisture, temperature and mechanical force.
oil-immersed power transformer tank with corrugated fin wall
Polymerization degree (DP) of transformer insulation material is the most accurate, reliable and effective criterion for insulation aging degree. According to the average degree of polymerization of insulated cardboard to judge the aging degree of transformer, we adopt the following criteria.
Evaluation Criteria of Average Polymerization Degree of Insulating Paper
Classified life-level hazard level
Average DP < 450 < 250
1) The index of life level is that the maximum residual tensile strength of insulating paper can be withstood reaches 60% of the initial value when the external short circuit occurs; the dangerous level is that the maximum residual tensile strength reaches 15% of the initial value.
2) The criteria of DP failure probability of Japanese insulating paper fibers are as follows: 1) DP > 450, failure probability = 0; 2) 450 > DP > 250, failure probability =( 450 – DP) / 200; 3) 250 > DP, failure probability = 1.
3) The residual life of transformer is estimated by average DP, i.e. nL/n0= (1 – r) L, where n0 is the starting value of average DP; nL is the average DP after L; L is the number of years; R is the average decline rate of DP.
CORRUGATED FIN FOLDING AND WELDING MACHINES
corrugated fins wall making machine
corrugated fins wall seam welding machine
steel roll feeding machine
corrugated fins wall leakage testing machine