Motor Current Signature Analysis on Gearbox Motor


Noise and vibration was investigated on a 7.5 horsepower, 1750 RPM, 575 Vac motor and gearbox using the ALL-TEST PRO™ OL (ATPOL) motor current signature analyzer. One set of data requiring less than one minute of data provided the information necessary. The number of rotor bars, stator slots, bearing information and gears was not available. The lack of information did not hinder the ATPOL in immediately identifying the faults.

Discussion Although lightly loaded, the ATPOL automatically identified casting voids (Figure 1), an electrical fault in the stator (Figure 2), gear problems and identified the number of rotor bars (48) and stator slots (36).

Figure 3 shows the automatic analysis display shown in the ATPOL software.


The ALL-TEST PRO™ MD kit consists of:

  • ALL-TEST PRO™ OL motor current signature analyzer
  • ALL-TEST PRO™ 31 and ALL-TEST IV PRO™ 2000 motor circuit analyzers
  • EMCAT motor management software
  • ATPOL and Power System Manager software modules for EMCAT