Ionization Studies in Paper-Insulated Cables---I

A research investigation of the ionization phenomena which occur in paper-insulated, high-voltage power cables is being made at the Harvard Engineering School under the auspices of the Impregnated Paper-Insulated Cable Research Committee. The paper presents some of the preliminary results which have been obtained, certain tentative conclusions that are suggested by the data and a description of the method developed for making the measurements. It is a preliminary report and in subsequent papers it is intended to record the progress of the investigation as it proceeds. The paper consists essentially of four parts as follows: (a) A number of curves of power, power factor and capacitance taken on samples of cable at two frequencies and over a wide range of temperature. These curves show well-known characteristics but in order to exaggerate these efects, cable models were made up to simulate the general conditions in a cable--one model consisting of glass and air only and another of glass, air and paper. Tests of these cable models gave very interesting results, particularly with reference to power factor. They also show rather clearly the baffling action of paper and the effects on power, power factor and capacitance when this baffling action is eliminated. In practically all the curves, the power and power factor begin to increase rapidly at a lower voltage gradient than the capacitance. (b) Discussion of the results obtained and certain tentative conclusions which may be drawn from the results so far obtained and reported herein. 1.