As a great number of induction motors are used in industry, their safe and consistent operation is highly required. There seem many motors close to the end of their lifetime after a long term operation but little attention has been paid to their maintenance due to requirement of cutting cost. But early identification of a weak motor and its replacement is typically very inexpensive compared to the costs of plant down time and rushed repairs. Thus, establishment of an easy and effective fault diagnosis method has been strongly required to assure operation with high reliability.
Short-circuit faults of winding is one of the most probable faults in motor drive systems. This paper proposes a novel and simple method for diagnosing short-circuit failure in stator windings of motors under load condition at site. The method involves probabilistic process for a gauging the probability of fault occurrence by considering distributions of features, i.e. magnitude and phase of current flowing into stator windings, depending on the condition of the short-circuited winding. A series of laboratory experiments and analyses of the results for motors with artificially introduced short-circuit fault proved that the proposed method is promising under load conditions.