To improve the condition evaluation accuracy of protective devices, a method based on the variable weight-ridge distribution function is proposed. Firstly, the main influencing factors of the protective device operation level are analyzed. A new index is supplemented, and the condition-evaluation index set for protective devices is further improved. Secondly, the extremum processing method is utilized to standardize the indices. Subsequently, the fuzzy analytic hierarchy process and entropy weight method are employed to determine the combination weight coefficient, and then the variable weight principle is introduced to adjust the weight coefficient of each index. Meanwhile, the semi-ladder and semi-ridge membership function distribution model is selected and compared with the triangle distribution model. Finally, the weighted average operator is selected to evaluate the state of the protective device. Case study shows that the proposed method can more accurately reflect the operating status of protective devices, while providing a reasonable reference for condition-based maintenance and risk assessment.
