In order to improve reliability and reduce the life-cycle costs of oil-immersed transformer, the introduction about condition-based maintenance for oil-immersed power transformer is imperative. For the service life of oil-paper insulation determines the service life of the whole transformer, the establishment of oil-paper insulation condition assessment method and model is the precondition of condition-based maintenance. In this article, the evolutionary radar chart is introduced in the condition assessment process of the oil-paper insulation and the assessment method combined preliminary evaluation about single index and multi-index comprehensive evaluation is established as well as the complete process of condition assessment about both qualitative assessment and quantitative evaluation. The cases analysis shows the steps of this method are simple and effective in the condition assessment for the oil-paper insulation and this method also can be achieved easily online, which provides a new way to online condition assessment about oil-paper insulation.
