Progress in High-Tension Underground Cable Research and Development

This paper deals primarily with the ``solid´´ type paper insulated high-tension cable, the development field still ahead being extensive. A review is given of the progress made during the past four years. The research and development work which made this progress possible is outlined, only the more important features being considered. Particular attention is given to void formation both in the factory and in the field, and methods of arriving at some understanding of this are demonstrated. The conclusion is drawn that void formation under service conditions is inherent in paper insulated ``solid´´ cables. Methods of reducing the size and duration of voids, and increasing their pressure, thereby reducing the possibility of ionization deterioration, are carefully considered. Oil reservoir feed at the joints is of great value in this respect. This is dealt with in detail. Research data on ionization and other characteristics of finished cable and cable materials are presented.