Thermal Transients and Oil Demands in Cables

A simple method is given for the precise calculation of temperature variations in underground power cables due to sudden changes in loading. It is shown how the same method is employed for finding the oil demands of oil-filled cables under similar circumstances. A generalization is introduced which permits the temperature variations and oil demands of cables to be readily calculated for load variations of any sort whatever. A method of finding the pressure at any point in the cable insulation at any time is also outlined. The simplified methods eliminate the necessity for a knowledge of higher mathematics and Bessel functions, which would be required in using the fundamental equations. Calculating charts and other devices permit complete solutions to be obtained in less than 290 per cent of the time formerly required.