Alternatives for Assessing the Electrical Integrity of Induction Motors

The early detection of motor deterioration can increase plant availability and safety, and maintenance personnel often utilize periodic inspection methods such as insulation resistance testing to accomplish this; for very large and crucial motors, expensive and sophisticated monitoring procedures are sometimes implemented, although such applications are rare. This paper presents two alternatives to traditional procedures that are appropriate for detecting stator-winding deterioration in three-phase induction motors of the sizes commonly found in the process industries, based on the results of a recently completed research project. The use of an effective-negative-sequence impedance as a predictor of incipient failure is recommended.