Vacuum insulated switchgear（VIS） is a new kind of power equipment which uses vacuum as insulated medium instead of SF6.The insulation performance

the maintainability of vacuum system and current carrying capacity are needed to technically investigate.To analyze the current carrying capacity of VIS

a thermal model has been built based on considering characteristics-thermal radiation and temperature-dependent properties of material-of vacuum insulation.The long-term heat calculation of the thermal model has been done by using finite element analysis software-ANSYS.The analysis concerning several factors’ effect on current carrying capacity is given.Moreover

the feasible range of current carrying capacity and some design advices of 40.5 VIS are also given.