Stability of epoxy-impregnated AC superconducting winding

AC superconducting composite wires for 50-60-Hz application are susceptible to disturbances due to wire motions, because matrices of the wires are highly resistive CuNi. Instability of the wires is one of the most serious problems in developing AC wires of large current capacity. An effective technique to reduce the wire motions is to impregnate the windings. It is demonstrated that epoxy impregnation is an effective technique to stabilize AC superconducting windings and that the AC losses can be cooled sufficiently by heat conduction through the epoxy. The characteristics of epoxy-impregnated 100-kVA-class AC coils are experimentally and theoretically compared to those of non-impregnated coils.<>