Abstract
A superconducting coil may be damaged by ohmic heating in itself when quench occurs. Therefore it is necessary to detect quench as fast as possible and to protect the superconducting coil from its overheating. However the conventional electric quench-detecting system is vulnerable to the electromagnetic noise, so it is required the high sensitive and reliable quench-detecting system.
In this paper, we propose a partial active power detecting method as a new type of the quench-detecting system. The active power consumed in the coil is used as the quench-detection. That is, when the active power gets to or is greater than the some threshold, it is recognized as quench in the coil. The active power has DC component in general. Therefore low pass filter (LPF) is available to eliminate the electomagnetic noise superposed on the detecting system. In order to deal with only the active power, reactive power is cancelled beforehand by the differential method. This detecting method is useful for the both cases of DC and AC power circuit. Experimental results show that this method is useful to detect the quench in the superconducting coil.
