| 摘要 |
PURPOSE:To quickly detect normal conductive transition through detection of quench from a difference between a signal whose current phase is led by 90 deg. and a voltage, by paying an attention to the fact that a resistance component appears in the superconducting coil and the current phase leads during normal conductive transition of the superconducting coil. CONSTITUTION:When normal conductive transition occurs, a phase difference 0 is generated between a voltage signal e' and a current signal i' and it gradually becomes large. Therefore, a difference signal epsilon which is an output of a subtractor 11 increases its amplitude gradually and it becomes an AC voltage which is different from the current i in the phase of almost 180 deg.. This difference signal epsilon is proportional to a voltage drop due to the resistance value of the superconducting coil 1. Therefore, the signal p multiplied by the current signal i by the multiplier 12 is also proportional to a moment value of effective power. The output p of the multiplier 12 is smoothed by a low-pass filter 13 and is compared with a specified reference value Vref by the comparator 14. When the smoothed signal P exceeds the reference value Vref, the comparator 14 issues an alarm signal S. |
