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Rotor Bar Testing – Ultrasonic

Test Overview

Ultrasonic testing of a rotor is an effective method of pass/fail testing performed on a rotor’s end rings. Ultrasonic testing is meant to reveal internal/structural anomalies in an end ring that may lead to mechanical stress.

Test Deficiencies

Ultrasonic testing is best used to diagnose/affirm suspicion of casting defects, but is limited in its use due to the results being notoriously difficult to analyze. The test results are often inconclusive and can raise more questions than answers.



  1. S. L. Nau, D. Schmitz, and W. de Lima Pires, “Methods to evaluate the quality of stator and rotor of electric motors,” in Proc. IEEE 10th Int. Symp. Diagn. Elect. Mach. Power Electron. Drives (SDEMPED), Sep. 1–4, 2015, pp. 69–70.