Inter‐laminar fault analysis of magnetic cores with grain‐oriented electrical steels under harmonic distortion magnetisations

Abstract

Inter-laminar faults (ILFs) have major impacts on the overall performance of the electrical machines and power transformers, among which extra power loss and hence lower efficiency could be highlighted. This paper presents an in depth analysis on energy loss and energy loss components of stacks of Grain-Oriented (GO) electrical steels subjected to different kinds of ILFs, under sinusoidal and non-sinusoidal inductions. Practical methods are developed to monitor quality of the magnetic cores, based on the measured static and dynamic hysteresis loops (SHL and DHL). The experimental results showed that, ILFs have a significant impact on the dynamic performance and dynamic energy loss of the cores, while their impact on the hysteresis loss is negligible. Furthermore, they become more destructive under non-sinusoidal inductions, and hence condition monitoring of the magnetic cores is more important for these applications.

A Phenomenological Approach for Condition Monitoring of Magnetic Cores Based on the Hysteresis Phenomenon

“…Magnetic hysteresis loops may take a variety of different forms which depend on magnetising regime, magnetic and electric properties of the materials, and quality of the cores. Experimental and analytical approaches based on the hysteresis phenomenon have been previously developed by the author for core quality assessment, under sinusoidal [4,11] and nonsinusoidal excitations [32]. To study impacts of the artificial faults on the hysteresis behaviour, DHL of the test samples were measured for the range of magnetisation; the results under sinusoidal induction of 50 Hz and peak flux densities of 1.0 T to 1.7 T are shown in As a phenomenological impact of ILFs on the hysteresis performance of the magnetic cores, Figs 9 and 10 show that peak magnetic field strength Hm* is remarkably increased by increasing number of the shorted laminations, which has a direct impact on total energy loss per cycle.…”

Magnetic Flux Density under Single Harmonic Distortion

“…However, since there is no mutual operation of magnetizing primary current and demagnetizing secondary current determined values of the active power losses and obtained magnetic flux density of the magnetic core may be different than during its operation. Toroidal magnetic core of tested iCT is made of Ni80Fe20 tape that magnetic properties under harmonic distortion are the subject of studies presented in this paper [10][11][12][13][14].…”