Tests of paper-insulated high-tension cable

The paper deals with those tests which are involved in specifications. The discussion is from the standpoint of the purpose and significance of the various standard tests which are made rather than that of the technic of the details of testing. A considerable number of data are given. The subjects treated are purpose and importance of tests of cable; insulation resistance test; high voltage test; dielectric loss and power factor test; “ionization” test; bending test; accelerated life test; preparation of samples for high-voltage tests and tests of components. The possible significance of wide variation in some of the properties of cable is discussed. The relation found between time and voltage based on a large number of tests of both three conductor and single conductor cable is discussed at considerable length. A test for stability of the impregnating compound is described as is also a proposed standard load for dielectric-loss testing. Some data are given showing the effect of repeated bending on lead and how that effect is influenced by the tensile stress in the lead. The paper concludes with a list of the ways by which, in the author´s opinion, progress can be made in the improvement of the quality and the design of paper-insulated high-tension cable.