The dielectric strength of glass-an engineering viewpoint

The purpose of this paper is to provide the engineer with co-ordinated information and data regarding the dielectric breakdown of glass which will permit him to apply this insulating material more effectively for high dielectric strength. In the discussion of the subject, particular attention has been paid to "edge effects" and other factors which cause wide variations in breakdown voltages-variations which are responsible for many of the seeming inconsistencies found in published results on the dielectric failure of glass and other materials. The author has concluded that it is possible to make a reasonable approximation of the breakdown voltage of glass, if the conditions of the test or of the application can be sufficiently well determined. The characteristic breakdown curves of this paper do not represent the results of any one series of tests, but are rationalized from data selected from many sources, including unpublished tests. The data curves included refer mainly to Pyrex* glass, but corresponding data have also been included on electrical porcelain because of the interesting comparisons shown.