Studies into the effectiveness of the electromagnetic stator core test

Stator interlamination insulation in large electrical machines relies on routine testing for integrity. Thermal testing originally using a high flux test (HFT) has to a large extent now been replaced by a low flux electromagnetic test (EMT) where the fault current in any interlamination insulation failure is detected. A number of alternate approaches have been developed with differing metrics and acceptance criteria. This research analyses how the differing EMT techniques correlate to each other and to the HFT, plus how lamination segmentation can affect HFT test levels. It further draws together both recently published work and new insights from research into EMT effectiveness (particularly of the dominant EL CID system) to improve the reliability of its result interpretation. The impact…