Quench Initiation and Propagation in GdBCO Racetrack Pancake Coil for Large-Scale Rotating Machines

Quench tests of a GdBCO racetrack pancake coil were conducted in liquid nitrogen at 77 K. Minimum quench energy and two-dimensional normal zone propagation velocities of the coil are discussed. Longitudinal normal zone propagation velocities in the curved section were almost twice those in the straight portion due to stress effects, showing that protection of the straight portion is of greater importance than protection of the curved portion when using racetrack-type, GdBCO pancake coils in large-scale rotating machines.