Impact analysis of the capacitive coupling sensor on bushing external insulation

Abstract

Online impulse frequency response analysis (IFRA) method is proposed and developed as a new technique to detect the winding mechanical deformation of a running transformer. The preliminary application of IFRA has been realised by using the bushing capacitive coupling sensor (CCS). However, whether the installation of the sensor affects the normal operation of the transformer is still unknown. To study above problem, this study first establishes a simulation model for transformer bushing based on the finite-element method and discusses the influence of sensor installation on the electric field distribution of capacitive bushing. The simulation proves that the installation of the CCS has minimal effect on the safe operation of the bushing. Second, the bushing withstand voltage tests are conducted in a lab, which proves that the installation of CCS meet the requirement for safe operation of capacitive bushing. Finally, the CCSs are installed on running power facilities, and the long and safe running experience indicates that the bushing and related facilities are unaffected by CCSs. The simulation analysis, withstand voltage test, and field application verify that the installation of CCS would not threaten the safe operation of high-voltage bushing, laying the foundation for engineering application of IFRA.