Partial discharge detection method for lower porcelain shell of oil paper insulation bushing based on spatial UHF signals

The partial discharge in lower porcelain shell of oil paper insulation bushing is one of the important reasons for transformer failures. Based on the analysis of the oil paper insulation bushing structure characteristics, the finite difference time domain simulation model of the partial discharge in lower porcelain shell is established. And the path of UHF signal of partial discharge is obtained that the signal spreads through the insulation between capacitor screens and oil passage to the outer space. Then the lower porcelain shell partial discharge detection method based on the space UHF signal is proposed and verified.