R&D of 19 kV class splicing device to connect high-voltage instrumentation wires and cable

Abstract

As transition connection in ITER machine, a large number of splicing devices (SDs) will be developed to connect the high voltage (HV) signal wires from different types of sensors installed in the superconducting magnet system to the HV cables connected with the feedthroughs installed in the cryostat wall. The structural design of 19 kV class SD aims at avoiding the electromagnetic interference and obtaining enough dielectric strength under high vacuum and cryogenic temperature environment. To avoid Paschen discharge under low vacuum, much attention is paid on the helium tightness of 19 kV class SD. To investigate the influence of the void in epoxy resin on the insulating performance of SD, the electric field analysis based on finite element technology is performed, the results indicate the peak electric field is much higher than the finite element model without void, which indicates that the void can lead to charge accumulation near metal electrode and electrical breakdown of insulating materials. Further tests indicate the insulating rod manufactured by using glass fiber wet winding under vacuum environment can reduce void in epoxy resin less than 2%, and the cryogenic electrical insulating performance of 19 kV class SD satisfy the technical specifications.