Investigation of short-circuit fault effects on non-oriented steel at different range of magnetisations

Short circuits between sheets of magnetic core of electrical machines in service are due to inter-laminar insulation damage, manufacturing defects, edge burrs and winding faults. These inter-laminar faults lead to circulating eddy currents between the affected laminations which are larger than seen in normal operation. This paper focuses on the effect of edge burrs faults on machine laminations at different set-points and different magnetising frequencies. The experimental study is carried out by using strip tester. Based on the obtained results the presence of edge burrs faults have significant effect on the magnetic properties of magnetic cores. This study has also shown that the induced eddy currents are largely dependent on the position of the fault (edge burrs) as well as on the number of shorted laminations. Moreover, power loss separation has shown significant increase in eddy current losses component with increasing number of shorted laminations.