EDDY CURRENT LOSSES IN CABLE SHEATHS - 1. CONSIDERATION WITH THEORETICAL FORMULAS.

The conventional method of calculating eddy current losses in cable sheaths, especially for single-core cable system, is now to be reconsidered because high-current cables realized by large conductors, and/or forced cooling are increasingly used for power transmission, and also because low-resistance aluminum sheaths are widely used for the cables instead of lead sheaths. This paper covers theoretical formulas. The new method of calculation extended from J. A. Tegopoulos' formulas is developed by the electromagnetic field theory for single- and three-core cable systems. This method which takes account of both circumferential and of radial distribution of eddy current gives a theoretically more rigorous solution than obtained in the past. The CPU time of a digital computer required for the calculation of losses about 0. 5 sec per case. General properties of eddy current losses in cable sheaths are described, and interrelations between these and already reported formulas are discussed along with the calculated results.