Simply put, Variable Frequency Drives (VFD) are inexpensive devices that provide a means to adjust the speed on an AC motor.
By running a motor at a slower speed, the amount of energy the motor uses is greatly reduced.
In fact, the consumed power of a variable-torque load, such as fans, pumps and blowers is proportional to the cube of its
rotation speed. In laymen’s terms, this means that small reductions in speed create large energy savings.
In the graph below, when the system is run at 60% speed, the consumed power is reduced from 100% to 30%.
The energy savings is quite an incentive and typically produces a ROI on the VFD investment of less than two years.
However to help accelerate the implementation of these systems, the energy companies offer incentives.
Duke Energy offers $40 per horsepower on the VFD that would cost about $1,100 on a 20 HP model. Obviously, this drastically shortens the ROI.
Check out Duke’s video and incentive program application.
Other local power companies like IPL, Vectren and many of the rural cooperatives offer similar incentives. Please contact your power company before starting your project.