Developing techniques for testing magnetic properties of electric steels. I. Epstein’s apparatus (Review article)

The review briefly describes the history of development of techniques measuring magnetic parameters of one of the materials which are of vital importance for energy generation, electric engineering, radio engineering, and other branches of industry, i.e., electric steel, whose quality determines operational characteristics of numerous devices, such as generators, transformers, electric motors, magnetic conductors of relay switches in various automated systems, etc. The development of techniques for measuring its magnetic parameters is reviewed starting with the advent of Epstein’s apparatus, which was designed at the turn of the century [1] and has remained an instrument used in resolving controversies between suppliers and consumers of electric steels, and ending on contemporary methods of testing roll steels using complex electronic circuits incorporated in automatic control systems of factories. In connection with the spread of magnetic parameters of electric steels (in sheets, rolls, and batches), the issues of standardization and selection of measures for more reliable characterization of steels are discussed. Instruments and facilities for classification and distribution of steels in batches with uniform characteristics are also described.