Testing high-tension impregnated-paper — Insulated, lead-covered cables

D. W. Roper: The paper by Mr. Lee (the best discussion of the subject of testing high-voltage cable that has ever been presented to the Institute) contains a great amount of interesting information all drawn from the experience of one cable manufacturer. Some of the conclusions which he draws are, therefore, rather limited in their application as they refer solely to the particular type of insulation with which he is familiar. As will appear later in this discussion, there is a wide variation in the characteristics or properties of the insulation made by the different manufacturers. For the purpose of broadening our view and thus improving our perspective, and not for the purpose of making any invidious comparisons between the products of the several manufacturers, I am going to quote some of the results that we have obtained in testing the product of a number of cable manufacturers, in the hope that I may be able to show how some of the conclusions given by Mr. Lee should be modified. On the eleventh page of his paper, Mr. Lee cites the case of the failure of an experimental length of cable connected to a 110-kv. three-phase overhead line, and states that the examination revealed absolutely no discernible cause for the failure.