Fault analysis and solution in current sharing test of ITER PF converter bridge

International thermonuclear experimental reactor (ITER) poloidal field (PF) power supply is composed of 14 sets of AC/DC converter units. Converter bridges are the key components of ITER PF converter unit, which is supplied by converter transformer and output the on-load voltage (±1.05 kV) and the rated DC current (±27.5 kA). There are 12 thyristor branches in parallel on each arm of the converter bridge. Therefore, the current sharing test is essential to verify the current sharing characteristics of the converter bridge arm under steady rated current. At present, the current sharing tests of Converter Bridge for 14 sets of converter units have been completed. During the test, there have been all kinds of faults. Accordingly, the fault reason should be analyzed firstly, and then corresponding effective measures should be taken for specific reasons. This paper mainly presents the fault analysis methods and the corresponding treatment measures aiming at all kinds of faults appearing in the test. The contents described in this paper can provide guidance and reference for current sharing test of high-current converter applied in other fields.