How to Evaluate Insulation Condition of 750kV Power Transformer Based on FDS

Abstract: The reliability of power transformer depends to a large extent on the insulation system. The lifetime of power transformer shortens with the deterioration of insulation system. The power transformer is expected to extend its service life and operate safely. Therefore, insulation diagnosis and lifetime evaluation are necessary. In this paper, a new test method based on frequency domain spectroscopy (FDS) is presented. The 750kV power transformer in Lanzhou East substation is measured on site through the FDS method. The measured results are consistent with those of preventive test. The water content of power transformer is qualified and insulation condition is good. The FDS method, a new preventive test method, will be widely used in future. 

Key words:  oil-immersed transformer, dielectric response, FDS, insulation, aging