Model-based eccentricity diagnosis for a ship brushless-generator exploiting the Machine Voltage Signature Analysis (MVSA)

In this paper a study about the different effects of shaft eccentricities on the external electric variables of a brushless salient-pole synchronous generator for ship onboard service is presented. Static and dynamic rotor eccentricities were simulated by using a dynamic mesh-model including inductances computed by an improved MWFA-based analyses and by 3D FEM, and taking in account the damping effect of the parallel paths inside the machine. Current and voltage steady-state waveforms were analyzed by FFT; no-load voltage harmonics appeared as good candidates as fault indicators, given their dependence on level and type of eccentricity. Some voltage measurements on the real machine are also reported and discussed.