Development of quench detection/protection system based on active power method for superconducting magnet by using capacitor circuit

When a quench occurs in a superconducting magnet, excessive joule heating in normal region may damage the magnet. It is necessary to detect the quench as soon as possible and discharge magnetic energy stored in the magnet. The authors have presented a quench detection/protection system based on an active power method which detects the quench regardless of a self-inductive and mutual-inductive voltages and electromagnetic noise. In the conventional active power method, the inductive voltages are removed by cancel coils. In this paper, the authors propose a method to cancel an inductive voltage using a capacitor circuit. The quench detection/protection system becomes more precise and smaller than the conventional system through the capacitor circuit.

► The authors have presented an active power method for quench detection.
► A method for improving its characteristics using a capacitor circuit was proposed.
► Quench detection/protection test for a Bi2223 superconducting coil was carried out.
► The proposed method was more useful than the conventional one.