The eZEio Controller is compatible with Invertek VFDs. Variable Frequency Drives, (VFDs) can control a motor's speed by changeing the frequecny of the drive voltage. They are controllable and configurable through the ezeio's Modbus interface. When used as a fan control, they can lower the required power by reducing the air conditioning requirements. This can occur in commercial buildings during periods of low occupancy when comfortable temperatures and air quality can be maintained at lower air flow rates.