| 摘要 |
PURPOSE:To make it possible to protect a coil by detecting a quenching generated on the coil in a highly sensitive manner by a method wherein, when a DC chopper circuit is turned OFF, a protective means, with which the excitation of the coil of a superconducting material will be stopped, is provided based on the detected voltage of the coil. CONSTITUTION:When a DC chopper circuit is turned OFF by receiving a synchronizing signal from a DC chopper circuit 12, a voltage detection means 13 detects the bridge voltage of a bridge circuit 6. A protective means is composed of a tripping signal circuit 14b, which works when the detected voltage of the voltage detection means 13, in other words, when the count of a counter 14a which counts the number of times sampling voltage exceeded the prescribed value, exceeded the prescribed value, and an open-circuit signal is sent to a circuit breaker 2. As the voltage of a coil is detected when the DC chopper circuit is turned OFF as above-mentioned, the effect of the value of the voltage while the coil is being excited is not inflicted upon the detected value, a quenching can be detected in a highly sensitive manner without being affected by the magnitude of the excitation voltage, and the coil can be protected. |
