The existing pollution discharge model has defects in discharge process simulation and flashover voltage prediction due to the difference of expansion mode and the incomprehensive consideration of dynamic process. In this paper

LXY4-160 disc insulator and ZSW56-126/8 post insulator are taken as the research objects

and the real type

double trapezoidal and rectangular equivalent plates are expanded. By introducing the equivalent water thickness and the equivalent conductive width

combined with the Dalton evaporation law and the Joule heat evaporation cooling equilibrium equation

the criterion of dry zone generation and arc initiation is proposed. Considering the time-varying resistance of the residual pollution layer during arc development

a dynamic model reflecting the whole process of insulator DC pollution discharge is established

and the model solution results are verified and analyzed. Based on the correlation of the calculation results of the deployment voltage of different plates

the correction of the deployment results of rectangular plates and its engineering application methods are proposed

and the applicability of each deployment method is analyzed. The results show that except for the LXY4-160 rectangular expansion

the error between the calculated value and the experimental value of the pollution flashover voltage of the dynamic model is within 10%. The real expansion is closer to the actual pollution flashover process

and the double trapezoidal and rectangular expansions lead to prolonged flashover time due to simplified structure. The correction of the rectangular expansion results can reduce the voltage prediction error and reduce the engineering application cost. The actual pollution flashover can be simulated by selecting the true expansion

only the predicted voltage can be selected to retain the simplified expansion of the main structure

and the results can be corrected when the rectangular expansion prediction deviation.