Rotor Bar Test Motor Current


  • Connect a current clamp to the volts input on the analyzer.
  • Place the current clamp around one wire of the three-phase power source.
  • Enter the correct sensitivity for the clamp, and account for a current transformer (CT) ratio if you measure on a secondary wire.


Rotor Bar Test Motor Current finds rotor bar defects in AC motors. The motor should be at least 50 percent loaded. Sidebands around electrical line frequency, spaced at the number of poles times the motor’s slip frequency, indicate a rotor bar defect. If the difference between the sideband amplitudes and the line frequency amplitude is less than 60 dB, suspect rotor bar problems.


  1. Create a job or open Analyze from a route measurement point.
  2. From the Analyze main menu, press F7 More Experts > F6 Rotor Bar Test Motor Current.
  3. Press Start or Enter to collect the data.
  4. Press Enter to view the data.
    One or more plots display after the data is collected.
  5. Press F9 Store Data to save the data to a route or a job, or press F8 Start to redo the measurement.