Magnetically coupled quench detector for superconducting magnets.

摘要

This note describes a low voltage signal detector that is useful for detecting quenches or excessive lead voltages at superconducting magnets. It can also be used for other applications where it is needed to detect low level signals present on high voltage installations. The application of isolated operational amplifiers is often not practical for high voltage applications because of their limited input voltage rating, common mode rejection and sensitivity. The described detector can withstand 7.5 kV input to ground voltage. It has a typical common mode rejection of (minus)150 dB at 60 Hz and an input sensitivity better than 1 mV. The magnetically coupled quench detector assembly is very sensitive to extremely small (order of 1 (mu)Amp) current changes in the sense windings. The detector assembly can therefore also be referred to as a micro current detector.