To solve the problem of fuzzy and uncertainty in evaluation of transformer oil-paper insulation condition

we proposed a method for evaluating the state level of oil-paper insulation based on a non-standard model. Firstly

the traditional method of approaching degree was abandoned

and the weight allocation coefficient wk was introduced to change the problem of weight distribution on each index into the optimization of objective function based on the sum of squares. Secondly

the grey target classification method based on sample set was adopted

and a circular grey target classification table for state classification of oil-paper insulation system was analyzed. Finally

a specific example was given to validate feasibility of this method. The results show that the evaluation results of the proposed algorithm and the actual operation state of transformers have consistency. This study can provide a useful reference for rational allocation of weight coefficients and calculation of grade intervals in condition assessment on oil-paper insulation.