Final tests of the power supply system for the W7-X superconducting magnet system

Wendelstein 7-X, a superconducting fusion experiment, is presently under construction at the Max-Planck-Institut für Plasmaphysik in Greifswald. The 50 non-planar and 20 planar coils are combined in seven electrical circuits with ten coils of the same type each. After the test of the seven individual power supply modules have been done in the past, now tests were made to show the proper co-ordination of the seven modules. In W7-X all seven electrical circuits are magnetically coupled. Therefore a special test load was designed and built up in order to simulate the magnetic coupling as realistic as possible. In the experimental program of W7-X eight magnetic configurations are defined, requesting different currents in the seven coil groups. During the tests all configurations were successfully tested, including the proportional energizing and slow discharging of the coils. Each power supply is combined with a protection system for the respective superconducting coil group. In case of a fast discharge all seven circuits have to discharged simultaneously to avoid an over current in the delayed circuit, caused by the inductive coupling of the coil groups. Another part of the final tests was the check of the proper reaction of the system after simulated failures. Also this kind of tests were executed successfully.