Research on insulation state evaluation and detection technology for 40.5 kV switchgear wall bushing

Abstract

Wall bushing is the core insulator of 40.5 kV air insulation switchgear, and its insulation performance determines the insulation level and service life of the switchgear. Wall bushing often appears partial discharge, insulation aging, grounded breakdown, and other problems after a period of operation. The main reason is the partial discharge of the equipotential line for the wall bushing. In this paper, the influence of the wall bushing equipotential line on the electric field distribution is systematically analyzed to improve the operating reliability and service life of the 40.5 kV wall bushing. Based on the electric field simulation of the equipotential line, the feasibility of the traditional live detection method is given. The characteristic gas detection method is proposed through air electrolysis, thermal decomposition, early warning of the development trend of the internal suspension defect state. Finally, it proposes corresponding preventive measures to avoid the development of internal suspension defect of wall bushing into a sudden grounding, and ensure the reliability of the system operation.

Keywords

• Air switchgear
• Wall bushing
• Equipotential line
• Electric field simulation
• Partial discharge