The magnetic properties of the ferromagnetic materials used for HTS transformers at 77 K

The properties of the magnetic materials, such as the amorphous alloys and the grain-oriented silicon steels, are essential to the design of high-temperature superconducting transformers. In this paper the magnetic properties and the loss characteristics of different ferromagnetic materials are measured at liquid nitrogen temperature. It is shown from experimental results that at 77 K the saturation flux density of the amorphous metal is about 0.3 T lower than that of the silicon steel, and the loss of amorphous metal is 4 times less than that of the silicon steel. Since the losses of materials at 77 K are higher than those of at room temperature, it is not economical to immerse the transformer core in liquid nitrogen.