The paper analyzes the heating defect caused by poor contact in the disconnection switch combined with other on-line detection means and charged load. The article considers that it is necessary to judge whether there are discharged defects according to super high frequency

ultrasonic partial discharge and SF6 gas analysis results. The tracking detection should be strengthened to avoid suspension

free particles or tip discharge defect due to bad contact. The analysis of defect severity should be analyzed combining with the structure

size of the tank and the charged load.