The long-term operation of insulating part of switchgear cabinet in the humid and hot environment is prone to moisture and reduction of insulation performance

leading to partial discharge and flashover inside the switchgear cabinet and effecting seriously stable operation of the equipment. Aiming at a typical partial discharge fault of bus bushing of 40.5 kV switchgear cabinet after moisture

the insulation performance test of bus bushing with different damage degrees is performed

and the electrical and material properties of the insulating parts before and after baking test are compared. The test results show that the partial discharge

insulation resistance and glass transition temperature can reflect the moisture degree of the bushing. The insulation resistance of the bushing after drying increases from the order of MΩ to 100 GΩ

the partial discharge decreases significantly

the glass transition temperature of the material decreases and different samples increase with the increase of moisture degree. The insulation performance of the bushing burned by discharge is damaged

and the degree of moisture can not be reflected by the partial discharge but by the insulation resistance and glass transition temperature. The results can provide support for the moisture analysis and diagnosis of the insualtion parts of the switchgear cabinet

and further prove the importance of dehumidification and partial discharge detection of switchgear cabinet to improve the reliable operation of switchgear cabinet.