Selection and performance of suspension insulators

Some of the methods used in selecting and checking suspension insulators during the past 15 years on a large electric power transmission system comprising some 3,000 miles of steel tower lines, most of which operate at 132,000 volts, are outlined in this paper. The results obtained through various tests, the use of these results as a guide for insulator selection, and actual performance and expected life of insulators are discussed. A large amount of laboratory and field test data is included, on the basis of which a life expectancy of 50 years for suspension insulators is believed possible.