Investigation of Rotor Impact on FRA Signatures in Induction Motors with Different Poles and Connections

The non-destructive nature of the Frequency Response Analysis (FRA) test is one of the reasons for gaining interest in the application of condition monitoring in rotating machines. The FRA technique is highly sensitive. Any small changes in the motor will generate a distinct frequency response, enabling early detection of the defect. This paper presents an in-depth experimental investigation of the rotor impact on FRA signatures of three-phase induction motors with different numbers of poles and connections. The experimental analysis was carried out using a frequency response analyzer, from which two distinct sets of measurements were taken. 1st set of measurements was taken to observe the effect of rotor presence on a 2-pole motor connected in star and delta. The same measurements were then repeated for 2nd motor with 4 poles. The results obtained from both sets of measurements are compared and analyzed. To enhance the comprehension of the results, statistical indicators are utilized. The finding highlights that the presence of a rotor can greatly influence the FRA signature. This helps further understand the FRA in motor and assists in accurate interpretation.