Influence of adjustable speed drive on induction motor fault detection using stator current monitoring.

Abstract

The detection of motor faults at their incipient stage is of prime importance to any industrial plant. The introduction of adjustable speed drives has improved the control and the efficiency of induction motors, however, this has changed the nature of motor faults and how they can be detected. Current signature analysis has caught the attention of researchers as a mature and simple technique for motor fault diagnosis. In this research three main ways of analyzing the current signature for fault detection have been investigated. These are: the power spectral density analysis, the current negative- and positive-sequence components, and the Park’s vector approach. Three major induction motor faults have been experimentally tested for the above diagnosis techniques: the bearing fault, the broken rotor bar, and the air gap dynamic eccentricity. Using an adjustable speed drive for controlling the motor while applying these fault detection techniques has been compared to the supply of the motor directly from the “mains” source and to a pure sinusoidal supply through a programmable source. This research has proved that using the power spectral density analysis is a good tool for induction motor fault detection regardless of the source of supply. This technique can be easily implemented in standard commercial adjustable speed drives, with no additional hardware requirements.