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Considerations for using VFDs with standard motors

Plant Engineering
Publication date: 
December 2016
Mike Howell, EASA Technical Support Specialist

Motors that meet the requirements of NEMA: MG1 Part 31 are designed for use with variable-frequency drives (VFDs). Motors that meet the requirements of NEMA: MG1 Part 30 may be suitable for inverter duty if appropriate measures are taken such as line conditioning. End users desiring speed and/or torque control often procure and install VFDs to modify existing applications where a standard-induction motor is in place. Frequently, they try to control costs by using the existing motor. There are a few areas of concern involving misapplication of a standard induction motor.

Topics covered include:

  • Speed-torque characteristics
  • Shaft currents
  • Installation