The flashover of roof insulator is a threat to the transaction power supply system. On the heavy fog day

insulator flashovers frequently

and the researches on it are less at home and abroad. In order to explain this phenomenon

firstly

we analyzed the airflow field distribution of insulator when train is running by using FLUENT. Secondly

we discussed the influence of water droplets with different dropping angle on the electric field of space near insulator by using ANSOFT. Finally

we studied the effective method to suppress the fog flashover by experiment. The results show that globules are easy to be generated when train runs at a low speed

and the wind shadow of insulator is the main place where globules form. Water droplets on high-voltage end are likely to cause insulator flashover. The wetting velocity of filth layer is relevant to pollution degree

and hot airflow has positive effect to suppress flashover.