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In power transformers and reactors, HTS AC coils and their supporting structures are accidentally subjected to fault current impacts and the resulting electromagnetic forces. Although single fault current (usually lasts only ~ms) may not cause electrical or mechanical failure of the HTS winding, it is important whether the HTS winding’s strength against fault-current-impact forces degrades during each impact period, which is named as accumulation effect and has been demonstrated in copper coils. This paper presents electromagnetic-mechanical simulations on a 22-pancake HTS AC winding under multiple fault-current impacts. The transient radial and axial deformations of the HTS winding by electromagnetic forces during multiple impacts are calculated and analyzed. The results indicate that the yielding strength of the HTS winding degrades after each impact, causing the eventual plastic deformation and potential Ic degradation of the HTS winding.
