Development of a protection system for an experimental SMES device

The development and testing of a quench detection and protection system for a small, liquid helium cooled, superconducting coil are described. The coil is being used as part of an experimental superconducting magnetic energy storage (SMES) device for power system applications. Special requirements are placed on the detection and protection system of such a coil as rapid energy exchanges are frequent. The detection signal is derived from a combination of the main coil voltage and a search coil voltage. The protection method is by way of an external parallel resistor. The problem of opening a circuit breaker in series with the coil is analyzed. Actual quench recordings are used to demonstrate the effectiveness of the system. The selection of the dump resistor value is considered.< >