For achieving the transition of the dielectric medium of gas insulated switchgear cabinet from SF

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to such environmentally friendly gas as dry air

it is an urgent issue to develop an embedded pole for dry air insulated switchgear cabinet with a smart structure and insulation level meeting requirement. In this paper

the electric field distribution of phase-to-phase and phase-to-ground of 40.5 kV SF

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embedded pole which is placed in the air insulated switchgear is analyzed. The result shows that the gas-solid surface electric field near the moving and static end cover as well as insulation rod of the arc interrupter seriously exceeds the standard

which is likely to cause surface flash-over. Based on gas-solid composite insulation theory

the electric field is optimized by such measures as adding grading shield network

improving appearance structure of insulation enclosure and redesigning insulation rod ect. Through simulation analysis

maximum field strength along the surface near the cover of arc interrupter after the optimal design is reduced from 3.4 kV/mm to 2.03 kV/mm

and the maximum field strength along the insulation rod is reduced from 4.1 kV/mm to 1.7 kV/mm. Partial discharge and lightning impulse tests are performed o

n the embedded poles before and after optimization. The arcing ignition voltage of the partial discharge test is increased from 35 kV to 62 kV

and the peak withstand voltage of lightning impulse test is increased from 145 kV to 218 kV

which proves the feasibility of the optimized scheme and provides a reference for the subsequent development and optimization of similar embedded poles at 40.5 kV and above.