Statistical dimensioning of insulators with respect to polluted conditions

Statistical methods for the dimensioning and specification of insulators with respect to pollution have formed the subject of many studies. However, such methods are not in widespread use due to its perceived complexity. A simple method is introduced for the dimensioning and verification of insulators with respect to polluted conditions, together with the detailed statistical method on which it was based. The statistical requirements for site assessment and the mathematical equations for the evaluation of flashover risk are presented. This basis is then used to obtain a simplified procedure to determine the minimum insulator flashover characteristic that will provide an adequate flashover performance. The selection of an appropriate test severity level for laboratory verification tests is discussed and equations are provided to calculate the test severity level from site severity measurements.