Testing strategies to evaluate non-oriented electrical steels losses

Abstract

Abstract-This paper presents an experimental comparative study of iron losses obtained by means of the Epstein frame, RingCore and dynamometer tests with non-oriented electrical steel samples. The comparisons are qualitative and they are intended to show the importance of carrying out other tests to evaluate electrical steels in addition to the standard Epstein frame method. In industry, complex or costly tests are avoided, whenever it is possible. This study shows that the ring core test can be a low cost solution since it is effective. For the manufacturer point of view, comparing different commercial steels at purchase time with a simple process is an advantage.Index Terms-Non-oriented electrical steel, iron losses, iron losses measurement, Epstein frame test, ring core test, dynamometer test. I. INTRODUCTIONThe growing demand for electricity, the need of investments, environment issues and lower costs production in the competitive market are factors that increase the concern of electric machine manufacturers with their products performance. One of major concerns related to the efficiency of devices is the losses in electric and magnetic components. Electrical steel sheets are widely used in electrical machine industry. The iron losses in the core and the magnetic permeability are relevant aspects in the design and optimization process and, therefore, for consumer acceptance in terms of electrical motor efficiency. Companies are investing in specialized departments to carry out tests to characterize or measure the electrical steel quality related to the appearance of new materials and the development of new production processes. Such departments play a relevant role as they supply valuable data for companies guiding price negotiations, parameters for future projects and quality control data of ferromagnetic materials. There are several types of ferromagnetic materials. In this work, we consider three semi-processed non-oriented silicon steels, having low iron losses and used in rotational electrical machines. The materials investigated come from three different commercial suppliers. In this context, this paper presents a comparison between three experimental approaches for evaluating three steel suppliers. The materials under consideration have equivalent characteristics (from commercial point of view, the same magnetic losses). This work is the evolution of a previous

A Review on the Effect of Electrical Steel Manufacturing Processes on the Performance of Electric Machines

“…The losses at weld joints significantly increase when measured compared to the Epstein frame [26]. The toroidal core measurement can also be used to test real stator lamination stacks [27]. Therefore, the ring specimen measurement is more accurate and applicable to the electrical machine's lamination.…”