Superconducting AC generators

The utilization of superconducting field windings in large ac generators gives promise of reduced size and weight, increased efficiency and better electrical characteristics over conventional copper-iron machines. This new concept in application to central station power generation could lead to machines with ratings beyond the limits set by present technology and even at present day ratings may have economic advantage. Also the low weight to power ratio of this type of machine makes it attractive for advanced airborne systems. Because of these attractive characteristics, the engineering schools and the large generator manufacturers throughout the world have initiated programs to evaluate this concept. These programs range from machine design to system studies up to construction and test of prototype demonstration machines. The present paper will first review the general concept of a superconducting generator in contrast with a present day copper-iron machine and then outline the potential advantages of this new concept, both technical and economic. Based on design studies and test results of the prototype machines, critical development problems that can be anticipated for future, larger generators will be reviewed with special emphasis on those aspects associated with the superconducting field winding.