Suitability of Integral Horsepower (IHP) Motors on Variable Frequency Drives

This document by Nidec Motor Corporation outlines key considerations for using integral horsepower motors with variable frequency drives (VFDs), including compatibility guidelines, motor types, cable distances, and special application factors such as vertical motor use and harmonic distortion.

Key Points

  • Inverter Compatibility: Nidec’s Inverter Grade® insulated motors exceed NEMA MG-1 Part 31 standards, ensuring durability under VFD stress.
  • Hazardous Locations: Only specific Division 1, Class I, Group D motors are VFD-compatible; other applications need engineering review.
  • Cable Distance Guidelines: Specific maximum distances are recommended based on switching frequency and motor type to prevent failure.
  • Harmonics and Bearings: PWM waveforms can cause harmonic distortion and bearing damage; filters and grounding are often required.
  • Application Factors: Suitability is determined by torque type, voltage, speed range, cable length, switching frequency, and motor construction.
  • Warranty Terms: Inverter Grade® motors carry a 3-year limited warranty, Premium Efficient motors 2 years, and Standard Efficient motors 1 year.
  • Special Cases: Vertical motors, multiple motors on one VFD, and motors in high-humidity or non-operational settings require unique considerations.
  • Thermal Protection: Built-in thermal overloads may not function correctly with VFDs; consult VFD documentation for protection alternatives.