Comparison of PDA and EMI diagnostic measurements [for machine insulation]

There are two methods available for the online monitoring of mica-based insulation associated with high-voltage machines. Partial discharge analysis, PDA, is a time domain technique that measures and classifies electrical impulses that often occur at stator defects. Electromagnetic interference analysis, EMI, is a frequency domain technique that captures and classifies most of the high frequency electrical spectrum. This can include stator related defects as well as nonmachine related information. This paper presents a laboratory comparison of data collected by these two methods during the electrical aging of an 18 kV generator stator bar. These two techniques were found to produce similar results.