Supercooled-Al Transformer

Year after year, the electrical power to be consumed in the world becomes larger, and also power transformers must become larger in size and heavier in weight. In this paper, prospects for employment of deeply cooled Al conductors as transformer windings are considered. At liquid hydrogen temperature, 20°K, Al exhibits a resistivity of 3×10^<-11>Ωm, and it is about 1/1000 times of a normal Cu resistivity. For this subject some considerations are given by K.J.R. Wilkinson, but this paper makes examinations of it from a different standpoint. At the beginning, for a three-phase core-type transformer general expressions of its loss, weight, size, etc. are introduced in a simple case, and then using the obtained expressions, 190MVA three-phase transformers with supercooled-Al windings are designed, to be compared with the conventional transformer. From this culculations it results that in the case of maximum flux density B_m to be equal to conventional value the supercooled-Al transformer is about 1/3.5 times of a conventional one in loss and weight, and in the case of B_m to be decreased so that the transformer weight may be equal to conventional value the diminution of about 1/5.3 times is obtained in loss.