Coil protection for the 20.4 MWh SMES/ETM

The 20.4-MWh superconducting magnetic energy storage engineering test model (SMES/ETM) is large and stores nearly two orders of magnitude more energy than any man-made magnet to date. These characteristics pose unique requirements for coil protection in response to a normal zone. A method of detecting a normal zone, action taken to quench the coil, and the subsequent temperature and voltage response of the coil pack are presented. It is shown that a normal zone produces a significant resistive voltage that can be easily detected, the coil is driven normal at half-turn intervals by inductive heaters, and coil response is calculated to be benign, both thermally and electrically.