2024 Volume 32 Issue 2 Pages 467-472
Electrical steel sheets used in magnetic cores of electrical machines are generally coated with an electrical insulating coating to prevent oxidation and eddy current flow between layers. For this reason, when electrical steel sheets are annealed at 850°C or more, the insulation coating is destroyed, and the coating should be reprocessed. Therefore, we investigated how increase in eddy currents due to short circuits between laminations on eddy current loss in the case of laminated electrical steel sheets without insulation coatings. Comparing eddy current losses of ring samples without coating before and after lamination, the contact resistances was relatively large and the effect of conduction between the layers was not observed. In this paper, by measuring the magnetic properties of laminated ring samples with polished surface, which have different surface roughness, we report on the results in the study of the relationship between the surface roughness and eddy current loss.
