Metallic glasses in distribution transformer applications: An update

Abstract

Metallic glasses suffer substantially lower energy losses than their crystalline counterparts and, therefore, allow increased efficiencies of operation in transformers. This challenge posed by metallic glasses to the use of conventional, crystalline silicon steels as core materials in the manufacture of electrical distribution transformers has found increased recognition, internationally, among manufacturers and users of such transformers. This paper provides an update on the understanding of the behavior of these materials. The focus will be on the properties of Fe-rich metallic glasses, particularly the Fe-B-Si glasses, as these offer excellent soft magnetic characteristics and economic viability. The core loss characteristics of these materials will be discussed in some detail; a recent model for the loss mechanism will be reviewed. Results on the aging behavior of these metallic glasses will be presented, along with a model describing the aging behavior. Finally, the tendency of these materials to lose ductility following anneals will be addressed.