Magnetic properties degradation due to the cutting procedures in the case of electrical steel used in energy efficient electrical machines

Abstract

Nowadays electrical machines are the most important electricity consumer, because they are responsible for 70% of industrial demand. The improvement of the electrical machines' energy efficiency can be done among other methods, by using high quality non-oriented electrical steels. High efficiency electrical machines are considered a new trend and are gradually imposing themselves in motor manufacture worldwide. Efficiency upgrade of motors could have a positive impact on the environment, being well known that IE4 electrical motors are already available on the market. In the paper there were tested samples of M400–50A and N020 industrial steel grade, cut through mechanical and water jet technologies. The samples have a 300 mm length and a variable width comprised between 5 mm and 30 mm. To reconstruct the standard Epstein width of 30 mm, 2, 3, 4 and 6 samples were put together side by side. In order to determine the magnetic properties, a single strip tester was used. The energy losses and the relative magnetic permeability were analyzed as a function of frequency in the range of 10 Hz-400 Hz at a peak magnetic polarization of 1T.