REFRIGERATION LOAD CALCULATION OF A HTSC CURRENT LEAD UNDER AC CONDITIONS

A 5 kA(rms)/50kV HTSC hybrid AC current lead is developed within a BRI TE/EURAM cooperation between Alcatel Alsthom, Hoechst and Siemens, For the optimisation of the conductor geometry computer codes have been r ealised, For the evaluation of AC losses in the superconducting melt c ast processed Bi-2212 part, the Bean model has not turned out to be pr acticable especially when the current exceeds the 1(c)(T) curve, This is gf course related to the low n-value (n less than or equal to 10) o f the superconducting transition curve in this material, A new calcula tion based on experimental E(J,B,T) curves allows the evaluation of AC losses in the temperature range of interest. These results are used f or the calculation of the maximum stable length and the low temperatur e heat load which is more than three times smaller than in an ail meta l DC lead, Together with the 77 K heat load of the normal part of the AC lead, the overall 300 K refrigeration load is calculated.