Abstract
In large motor cores, faults caused by edge burrs between the core laminations can result in short circuit currents which may be large enough to cause burning or complete machine failure. This study simulates the impact of edge burrs on large motor lamination (300mm*300mm) by applying artificial shorts to lamination edges. This twofold study has investigated the impact of short circuit and the impact of short circuit positions on total power loss. Multiple shorts have been applied at different positions. It has been found that the induced eddy-currents are largely dependent on the fault position (edge burrs) and the number of shorted laminations even when only two laminations are involved. This study was further extended to include power loss separation into three components, the power loss separation has been applied to the case of higher power losses obtained under specific short circuit conditions at different magnetizing frequencies. Power loss separation has shown a significant increase in eddy current loss components with increasing number of shorted laminations.
Highlights
T HE CORES of electrical machines are normally built from thin electrical steel laminations to reduce the eddy current loss for high efficiency operation [1]
This paper has presented an experimental study of the effect of short circuit position on total power loss for stacks of two and three laminations of a non-oriented electrical steel
It was found that the power loss increases with increase in the number of shorted laminations and this increase of loss is dependent on position of the short circuit
Summary
T HE CORES of electrical machines are normally built from thin electrical steel laminations to reduce the eddy current loss for high efficiency operation [1]. The cores of electrical machines are subjected to different processes, which may have a direct impact on their properties. These include, mechanical damage during assembly, rewind or re-wedge, foreign particle during assembly, vibration, arcing, heating and degradation of the insulation between the sheets [3], [4]. Mechanical deformations shear causes burrs on the cut edges [5] These burrs tend to cause insulation breakdown between the sheets resulting in electrical shorting between the stacked laminations.
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Published Version
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