Electric Motor Analysis

Power and current signature online motor testing programs allow for the evaluation of motor circuit performance during operation and detect problems before they occur. Early detection of damaged rotors, power circuit faults, poor power quality, stator, air gap and eccentricity can lead to significant energy and maintenance savings by not allowing a defective motor to continue operation. Trending motor health over time can prevent unexpected down time and minimise costs associated with premature failures.

Typical root causes of failures that can be identified are:

  • Power Quality
  • Voltage and Current Waveforms
  • Harmonic Voltage Factor
  • Voltage THD

Power Circuit

  • Power Voltage Imbalance and Current Imbalance


  • Power Impedance Imbalance Phase Power Factors


  • Faults cause changes in peak in-rush current graph shape and duration


  • Evaluation: Pole-Pass Frequency sideband amplitude
  • Swirl Effect @ 5th Harmonic
  • Demodulation
  • In-Rush/Start-Up

Air Gap

  • Eccentricity
  • Amplitude of the 1st and 3rd sidebands of line frequency at the eccentricity frequency**
  • This technique is typically used to further diagnose a problem identified by a VCM survey