Evaluation of soundness of magnets in 3-50BT line

In March 2019, the bending magnet B15D broke down and the MR beam stopped functioning. It was suggested that this was caused by an insulation failure that occurred due to a water leakage. In the 3-50BT line, there are magnets designed similar to B15D and they might face similar issues. To evaluate the states of these magnets, impedance measurements and simulations were conducted for these magnets. It was found that the problem occurred in the lower coil of B15D. After replacement of the broken coil, B15D and other magnets operated normally. From the results of this study, it was suggested that impedance measurement can detect the insulation failure easily and will be useful for detecting the sign of coil damage in advance. (author)