The Design of a Rotating Dewar and Field Winding for a Superconducting Alternator

Abstract

The desire for large-capacity single-unit turboalternators has increased the size of such units to a maximum based on present technology. Aside from the obvious strength limitations imposed by present materials, the size of such machines is limited by heat transfer from the electrical conductors and by shipping considerations. In present machines, the field windings are convectively cooled by operating in a hydrogen gas atmosphere and the armature conductors are water cooled. The largest installations must be shipped disassembled and then assembled on site, which is” an expensive and exacting task. While large units are quite efficient, a sizeable portion of their inefficiency is due to resistive heating of the field and armature conductors, the remainder being due to bearing, windage, hysteresis, and eddy-current losses. Although field losses constitute only a few percent of the available output, they are significant over the life of the generator.