Discussion on “the testing of high-voltage line insulators.” Atlantic city, N. J., June 30, 1908

Percy H. Thomas: The testing of a high-voltage insulator by application of voltage from a spark-gap or other high-frequency discharge has an extremely important bearing on the type of insulator. A four-part insulator or a three-part insulator, in fact any large insulator, has its resisting power made up of a number of elements all practically in series. The possibility of the concentration of potential on certain parts of these insulators is well recognized. This condition is recognized as greatly reducing the breakdown voltage of an arrester. The feature I wish to bring out is that with very high frequencies this concentration effect is enormously multiplied. I believe that a careful study of this matter will result in some modification of insulator design.