Discussion on “electrical porcelain,” (Creighton), New York, February 19, 1915. (see proceedings for May, 1915)

A. O. Austin: The oldest impact method used in testing insulators is probably that of suddenly throwing in the switch on the primary of the testing transformer. This is rather uncertain, but usually results in a rather severe surge or suddenly impressed voltage on the insulator, and will puncture material which can not be weeded out where the voltage is held on continuously even at the point of flashover.