ith the introduction of modern electronics, advances in electrical circuit analysis, and a close W view of basic electromagnetic circuits, methods have been developed to measure the static electrical/electromagnetic properties of rotating machinery. A number of hand-held and portable motor circuit analyzers (MCA) have been introduced to the world market since 1985 providing several methods for viewing the basic properties of rotating machinery electrical components. Analysis methods can include simple resistance and inductance testing through resistance (milli-Ohms), impedance, inductance, phase angle, and more complex proprietary testing methods, taken on rotating equipment that has been de-energized. In the past the test methods had been very complex but are now relatively simple, requiring little training for operation but increased knowledge of electromagnetic circuits for complex analysis.For the purpose of the analysis results presented within this paper an ALL-TEST IV PRO"" 2000 motor circuit analyzer was selected as it provided resistance to one milli-Ohm, impedance, inductance, phase angle, and a special test that measures current response at measured variable applied frequencies. Test voltage and frequencies were applied at less than 10 V RMS, true sine wave, at applied frequencies from 100 to 800 Hz. The electric motors tested were provided at a number of locations and included either planned failures or failures that were first analyzed then investigated using alternate methods. Histories of MCA were analyzed from data collected over a period of approximately 15 years.Within this paper we shall present the basic theory of analysis on wye and delta connected electric motors, then the results of applied testing on several electric motors. Basic limits of unbalance shall be presented; however, while analysis and research continues, these limits should be considered guidelines and not absolutes as the range of electric motors that can be tested have included fractional horsepower electric motors to machines over 10,000 horsepower, 13.8 kV.The results of the studies presented provide a view of the application of static MCA for testing three-phase induction
