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Evaluation of the Relative Wear of the Insulation of the Power Oil Immersed According to the Data of the IEC60076-7 Standard
  • Mykhailo Poliakov
Mykhailo Poliakov
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The IEC 60076-7 standard contains a table of the relative aging rates of oil-immersed transformer cellulose insulation as a function of temperature, moisture and oxygen content. But these data are given for a limited range, with a large and variable moisture content step, which makes it difficult to use them in the course of parameter control, simulation of insulation aging processes and comparison with the results of known studies of the aging processes of cellulose insulation. The purpose of the work is to increase the accuracy of estimates of the rates of relative wear of the cellulose insulation of the power oil-immersed transformer by detailing the data of the IEC 60076-7 standard. To improve the accuracy of estimates of relative aging rates, a method of interpolation and extrapolation of IEC 60076-7 data was proposed, and on this basis, an assessment was made of the contribution of individual factors to the total rate of relative wear. As a result of the application of the proposed methods, a table of rates of relative insulation wear has been developed, which details tables A.3 and A.4 of this standard, extrapolates the data of these tables to typical ranges of factors that are used in modeling practice. The terms of the relative aging rate due to the mechanisms of oxidation, pyrolysis and hydrolysis have been obtained, which made it possible to synthesize new data on the relative aging rates with oxygen access and different moisture content of the insulation, as well as to connect two approaches to taking into account the factors that accelerate wear: multiplicative and additive.