Fundamentals for the Determination of EHV Switching-Surge Ratings

This paper develops a theoretical method which leads to an efficient practical one and provides a mathematical basis for establishing EHV switching-surge ratings. Detailed analyses of the major factors involved in EHV testing are presented. Application of statistical and probability mathematics to the test results indicates the necessity of a rigorous evaluation of the test data and the need for defining the environmental differences between laboratories. Statements of rating include references to error factors and the degree of confidence that a particular series of test results have a certain probability of occurrence.