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The development of superconducting generators is an 8-year program at Japan's Engineering Research Assn for Superconductive Generation and Materials. Current work is focused on the design, construction and testing of three types of 70-MW prototype machines, two slow-response and a fast-response models. So far, the research effort has yielded a field winding model, a partial rotor model and a stator core cooling model.

A prototype field winding for a 70-MW electric generator was fabricated from aluminum-stabilized superconducting cables. Rated for 3000-A operation, the field winding was subjected to heater and excitation quench tests to study its stability. The tests confirmed its cryostability at the rated operation current provided the rotor's centrifugal force field ranges from 4000 to 5000 G. A tenfold increase in the liquid helium's cooling occurs in the centrifugal force field as compared to the 1-G gravitational field.