Studies of stability of cable insulation

In connection with recent developments of new types of underground cables for high voltages, questions have been raised concerning the stability in service of impregnated paper insulation of the ordinary type. In addition to giving new data on the only reliable test method found for predetermining this stability — accelerated aging tests — this paper gives information on the mechanism of failure, and on the effects of variations in construction and materials. Long service life was indicated by the tests for good insulation of the ordinary type.