Protecting VFD-Driven Motors in
HVAC Systems

The “Greening” of America’s Buildings
The growing “green” movement has led to a flood of new standards including the US Greens Building Councils Building Performance Initiative, the Green Building Initiative, and LEED — all aimed at increasing energy efficiency and sustainability. Challenged to reduce energy consumption and to document savings, America’s facilities managers are installing variable frequency drives (VFDs) in HVAC systems as one of the best ways of achieving such savings.

The Promise of VFDs
VFDs reduce energy consumption by allowing motors to run less than full speed. When used to control air conditioning, air handling, or pump motors, VFDs can yield energy savings of 20 ~ 30% or more by allowing motors to run at reduced speeds to compensate for changes in load.

The Need for Shaft Grounding on
VFD-Driven Motors
But, VFDs can damage the motors they control. They induce currents on motor shafts that discharge through the bearings, causing pitting, fluting, and catastrophic motor failure. Without bearing protection, any savings from the use of VFDs can be quickly wiped out by the cost of replacing motors and by system downtime. To make HVAC systems sustainable as well as energy efficient, a reliable method of bearing protection is required.

Proven, Long-Term Bearing Protection
By diverting bearing currents safely to ground, AEGIS™ SGR Shaft Grounding Rings ensure the reliable, long-term operation of VFDdriven motor systems, locking in energy savings and making these systems truly sustainable and truly green!