where, x—Length of partial arc. In the example of Fig. 5.34, it consists of two parts, X1 and X2; I—Leakage current size that flows through the insulation equipment surface; A, n—Constants related to arc characteristics, A being closely related to the dielectric type and the state of the dielectric and heat dissipation status of the arc, etc.; n is decided by the arc current.
For the voltage drop in the remaining pollution layer, the remaining pollution layer segment without partial discharge is considered by simplifying it as resistance, which can be calculated with the following formula: