Early detection of insulation failures on electric generators through online Frequency Response Analysis

This work presents an application of Frequency Response Analysis (FRA) on the detection of insulation failures on electric generators. An equipment for FRA of electric machines has been developed and its online connection to an induction generator through a C-L-C T-type coupling is presented. It is shown that the coupling circuit implies in a design trade-off between the attenuation of the power signal at fundamental frequency (which may damage the electronics of the analyzer) and the useful area obtained in the FRA spectra. It is shown that a C-L-C coupling greatly improves the performance of a regular capacitive coupling, improving its attenuation at fundamental frequency while maintaining similar frequency response at high frequencies. Experimental results are presented to validate the proposed equipment.