Experimental Validation of a Diagnostic Index for Induction Motors Stator Faults

Motor Current Signature Analysis (MCSA) is usedfor non-invasive diagnosis of incipient or actual faults of gridsupplied induction machine stator defects, being the negativesequence component of current space vector the diagnosticindex most widely used. Supply unbalance and load influenceof the machine however affect the negative component andthey may cause the failure of the diagnostic procedure,Recently, deceleration test that may remove some drawbacksof MCSA, has been proposed for rotor and stator faultdiagnosis,In this paper it is shown that the Residual VoltageSignature Analysis (RVSA) obtained by the deceleration testprovides, once removed the intrinsic manufacturingasymmetry, a diagnostic index directly related to thepercentage of shorted furits. The main advantage of RVSA isthnt any influence caused by the supply unbalance and load ismasked. Therefore a new diagnostic index is presented that isthe residual voltage negative sequence component. The novelindex performances have been proofed thanks to a simplifiedmodel of the faulted machine and experimentally validated bya special test motor that allows the introduction of differentshort circuits. This novel index can be used to confirm theMCSA-based diagnostic procedure developed by the sameauthors.