High Voltage Testing of ITER Prototype Axial Breaks

Axial insulation breaks are needed in forced cooled cryogenic high voltage devices like fusion magnets for the separation of the high voltage area from the grounded pipe system. For the verification of the ITER requirement compatibility, a special type test series was defined for a set of cryogenic and room temperature prototype axial breaks. This paper gives an overview of high voltage type tests performed on a set of 5 cryogenic breaks and 3 room temperature breaks designed and manufactured by Babcock Noell. Direct voltage, alternating voltage, and impulse voltage tests were performed to reproduce in an economic way the different voltage loads during current operation, fast discharge, and fault events. In addition, for 2 cryogenic breaks, Paschen tightness was demonstrated at 35 kV DC.