VariTough® Inverter Duty Motors for VFD Applications

This document outlines the features, specifications, and benefits of U.S. MOTORS® VariTough® Inverter Duty Motors, specifically designed for commercial condenser units operating under harsh temperature conditions with variable frequency drives (VFDs). The motors include AEGIS® SGR protection and meet rigorous NEMA MG1-Part 31 standards, ensuring optimal reliability and long-term performance.

Key Points


  • Designed for commercial condenser units running on a single VFD in harsh climate conditions
  • Includes AEGIS® Shaft Grounding Ring (SGR) to prevent VFD-induced bearing damage
  • Available in horsepower ratings from 1/2 HP to 2 HP and speeds of 575, 850, and 1140 RPM
  • Equipped with Class F insulation and double-sealed ball bearings
  • Built to meet NEMA MG1-Part 31 inverter duty guidelines for long-term durability
  • Features a 4:1 constant torque speed range to handle seasonal RPM variations
  • Offered in both belly band and rigid base mounts with open drip-proof (ODP) shaft-up enclosures
  • Ideal for new installations or as a reliable replacement in demanding HVAC applications