Maple Grove, MN (June 4, 2013): Use of variable-frequency drives (or VFDs) enabled Byerly’s grocery stores to cut energy use by almost half in blower-fan motors at five locations.

“VFDs make the operation of refrigeration systems smoother. If you implement them with the proper control strategy, they can reduce power consumption by 20% to 30% in those units,” Abtar Singh said. More than 95% of all installations of heating, ventilation and air-conditioning (or HVAC) systems in the United States use single-speed motors rather VFDs.

VFDs save energy by running electric motors at variable speeds. They control the speed of the motor by changing the frequency or voltage of the alternating current (or AC) on which it runs. “When you reduce the speed of a fan motor by 20%, air flow decreases by 20%,” Singh said. “But energy use drops by 50%.”