Impulse Strength as a Measure of Cable Quality

Testing cables by means of the impulse generator, originally developed for cables, is becoming recognized more and more as a useful method for determining cable quality. It is felt that the amount of data accumulated during the past ten years is sufficiently large to be used in formulating a theory concerning the factors governing the impulse strength of cables. It is indicated in this paper that maximum rather than average stress should be taken into account when impulse test results are evaluated, since the maximum stress at breakdown is a measure of the quality of the insulation alone. This view is contrary to that generally accepted in this country although some workers in this field abroad have accepted this theory for some time.