Design and Manufacture of the RFX Magnetizing Winding

This paper presents the final design and main manufacturing aspects of the RFX Magnetizing Winding, now being manufactured by ABB. The winding is designed to store 15 Wb flux and consists of 200 copper turns wound into 40 coils. These are impregnated in groups to form 17 blocks, to satisfy mechanical requirements. The largest coils, with diameters exceeding 8 m, are demountable into two halves, for ease of transport and assembly. The peak turn current is 50 kA and the peak voltage per turn is 700 V. A special connection between the coils allows the resulting voltage across the terminals of each sector to be kept below 35 kV and the voltage to earth below 17.5 kV. To limit diffusion phenomena inside the solid conductors, the innermost 24 coils are wound with two conductors connected in parallel at the coil terminals, transposed with each other at the half coil. Polymide and glass tapes impregnated with epoxy resin provide good insulation without excessive thickness.