2016 Best Practices: Hand-Held Motor Analysis, By ALL-TEST Pro

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ALL-TEST PRO 5: The only de-energized, non-destructive, hand-held instrument you need for complete electric motor health analysis.

Detects faults in all motors and types, auto diagnosis with instrument, route-based testing and trending, and tests can be performed from distances of more than 1,000 ft.

1. A number of faults will cause a variable frequency drive (VFD) to ‘nuisance trip.’ This includes faults within the electric motor windings that cannot be detected with meg-ohm or ohm meters. Moreover, the motor may still operate in bypass for some time. If incoming power is satisfactory (+/-10% of VFD voltage rating), check the motor windings and cables with motor-circuit analysis to isolate the location of the fault (motor, drive, or cable).

2. A key, often overlooked, part of any electric-motor maintenance program is to ensure that motors are clean. Air passages, fan, and surfaces of the motor should be cleaned periodically. Contamination buildup on these surfaces will reduce the electric motor’s ability to cool itself, resulting in a shorter insulation life. Monitoring the electrical insulation condition with motor-circuit analysis will allow early detection of contamination buildup on the windings within the electric motor.

3. Larger motors may experience significant voltage drops at the motor terminals when starting due to high inrush currents. Problems that can result include long starting times and the inability to develop enough starting torque to meet the inertial requirements of the load. Long inrush periods can lead to abnormal winding heat which can shorten motor life. Inrush currents can be measured using electrical-signature-analysis test instruments.

ALL-TEST Pro
Old Saybrook, CT
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