Improved detection method for winding surge tests of large ACmotors

摘要

The error area ratio method of digitally comparing surge testringing patterns has been developed to aid in the detection of shortcircuits in motor windings. The sensitivity of this new detection methodis sufficient to detect one turn shorted in many hundreds. The methodcan be used to detect shorts among parallels in large motor windingswhich could not be detected with earlier measurement techniques.Detection of a single shorted turn in a winding of 5000 turns has beenachieved. In addition, detection of shorts among parallel windings hasbeen demonstrated. The authors describe the improved test circuit andnumerical analysis techniques utilized to compare surge test waveforms.Printouts to waveforms and descriptions of faults in large motors arealso presented