Modifying Electric Field of Tri-Post Insulator in a 320 kV DC GIL Based on Al2 O 3/SiC/epoxy Composite

Tri-post insulator plays a significant role in electrical insulation and mechanical supporting inside GIL. However, the extremely high electric field in the interface between the conductor and the solid insulation hinders the development of the tri-post insulator inside the DC GIL. In this work, the electric field distribution of SiC doped tri-post insulator inside a ±320 kV DC GIL is studied using electric-thermal multi-physics simulations. The results show that the electric field concentration at metal-epoxy insulation interfaces becomes less concentrated with the increase of the SiC doping content The maximum electric field strength of the tri-post insulator at the interfaces has a 53.7% decrease under steady DC voltage, and has a 25.0% decrease during polarity reversal. The potential application of such tri-post insulator is discussed.