Abstract: Simulation shows that the proportion of 3rd harmonic content in the magnetic flux of the three-phase five-limb core and the three-phase wound core is about 17 %. These cores are recommended to be prepared using thin-gauge and low-loss grain-oriented silicon steel. The service properties of ultra-stable low-loss silicon steel (USL) and high magnetic induction oriented silicon steel (HiB) were studied under different harmonic orders and harmonic contents. According to the loss separation model, the losses of different silicon steels are divided into hysteresis loss, eddy current loss, and excess loss. Compared with HiB silicon steel of the same grade, USL silicon steel has a similar proportion of eddy current loss and a smaller proportion of excess loss. Under the same harmonic excitation, USL silicon steel with a lower proportion of excess loss is less affected by harmonic, because the excess loss of silicon steel is proportional to the frequency.

Key words: harmonic, USL silicon steel, HiB silicon steel, loss