The electric strength of solid dielectrics under impulse voltages

This report is a record of a series of investigations upon the behaviour of various insulating materials under disruptive voltage surges, carried out with the object of filling serious gaps in knowledge in this important field. Particulars are given of a number of materials under different surge conditions, and a critical survey is made of the results obtained. The conditions necessary at breakdown for measurements to give the electric strength of the material under test are examined. The influence of electrode shape and immersion medium are discussed, suitable forms of test specimen for different materials are considered, and results of impulse tests at voltages up to 700 000 are given. The Director of the E.R.A. will welcome comments and suggestions from those who may have occasion to make use of this report.