Static eccentricity detection in synchronous generators by field current and stator Voltage Signature Analysis - Part II: Measurements

Static eccentricities raise a double fundamental frequency ripple in the rotor current of wound-rotor synchronous machines. The ac ripple leads to clear signatures in the no-load terminal voltage spectra, pushing up some voltage harmonics normally smaller in the healthy machine. Rotor current ac ripple and related voltage harmonics have been used for fault diagnosis in this paper. In Part I of the work, a theory for fault-related voltage harmonics in no-load machines with static eccentricity has been exposed, with simulations confirming the theory. In Part II, a 15 kVA four-pole fractional-slot generator has been used for experimental validation, featuring an innovative flange with exact and easy regulation of amplitude and direction of both static and dynamic eccentricities. The results have been discussed, taking in account the practical imperfections of the real test-bed.