Methods for diagnosing static eccentricity in a synchronous 2 pole generator

Three methods for diagnosing static eccentricity in a non-salient 2 pole synchronous generator have been investigated. The methods investigated are axial shaft voltage, vibration and armature current monitoring. The shaft voltage and armature currents were calculated using transient 2D finite element method (FEM) simulations. Measurements were then taken with no eccentricity and compared to measurements with various induced eccentricities. It was found that the simulations and measurements exhibited close agreement with significant changes in the shaft voltage frequency spectrums and large circulating currents in the parallel connected phase groups when eccentricity was present. The axial vibration frequency spectrums show a clear trend with increasing eccentricity. All of these methods provide an indication of eccentricity but further work is required to determine how conclusive each one is.