An Electromagnetic Probe for Detecting and Locating Discharges in Large Rotating-Machine Stators

The detection and location of discharges in rotating- machine high-voltage windings is useful in directing attention to abnormalities in the insulation structure which can lead to premature failure of the winding. In order to achieve a practically useful test it is necessary to distinguish between conditions involving many small size voids which are not severely limiting and relatively few large voids.