Whether you suspect a problem with a VFD or just want to make sure it’s functioning at 100% before ramping up production, our VFD health check services provide a simple solution. We’ll run an in-depth analysis to make sure the drive is functioning as needed and provide you with a detailed report that includes oscilloscope traces.

  • VFD Input – quality of the supply power including the following tests:
    • Voltage and Current Phase-Phase and Phase-Ground
    • Voltage unbalance
    • Current unbalance
    • Harmonics (THD and TDD)
  • VFD DC Bus – Voltage (Input and load conditions) and Ripple (Diodes, Capacitors and output loading)
    • The Voltage DC Level checks the value and stability of the internal DC-bus of the drive and influence of braking or power feedback (if supported by the drive)
    • The Voltage AC Ripple function detects rapid fluctuations and ac components on the dc-bus, if the peaks have a differing repetitive pattern one of the diodes could be failing, large ripple voltages are also indication of failing capacitors or VFD/Load sizing mismatch
  • VFD Output – Tests include
    • Voltage and Current Phase-Phase and Phase-Ground, Peak-Peak, Max Peak, Min Peak and Crest Factor
    • V/Hz Ratio – motor overheat or losing torque [A 10-degree temperature rise can equal 50% decrease in motor stator insulation life]
    • Voltage Modulation, Phase-Phase, Phase-Ground, Phase-DCBus
    • Fast modulation pulse dV/dt

Optional Testing:

  • Motor Input – Determine the influence of the cable, voltage drop, and reflection problems that can cause performance drop or damage to the motor. Voltage modulation measurements to detect if voltage peaks are too high (indicate cabling is not properly matched) 
    • Motor Shaft – Detect bearing grease flash-over currents that can damage motor bearings (electrical discharge machining)
    • Motor and cabling insulation resistance testing and documentation

VFD Backups

We can ensure you have the data needed to recover quickly in the event of a drive failure. Backup services may include creating:

  • Electronic copy of the configuration file
  • Record of the input and output points in use
  • Record of parameters that have been changed from the drive default
  • Record of options and accessories
  • Part number documentation and repair/replacement plan (plan for spares can be coordinated across multiple facilities if they are included in service)

VFD Configuration and Commissioning  

The default configuration of a VFD may work, or work with minimal settings, but consider saving up to 14% on energy costs by matching the configuration to the application. Proper configuration can also prevent excess wear and tear on those long lead time/mission critical mechanical components connected to the motor.

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