Industrial fans, pumps and air compressors use more than 50% of the total motor-related electricity used in the U.S.
According to the U.S. Department of Energy, industrial motor-system energy use could be reduced by 11% to 18% if all existing cost-effective technologies and practices for improved efficiency were implemented.
Variable Frequency Drives (VFDs) on motors can enhance process operations, especially for flow control, and can efficiently cut energy demand for pumps and fans.
Motors are sized to fit a maximum load and operate at a constant speed. But, demand on motors fluctuates. Greater power is needed at start-up; air pressure changes in a paint booth because doors are opened; more-viscous product is pumped through process lines.
VFDs control the difference between supply and demand by automatically matching the motor speed to the actual needs of the system based on input from sensors. VFDs control motors more efficiently than throttling or other means, which reduces energy bills.
Some notes for considering VFD’s to reduce the speed of pumps and fans:
An 80% motor speed uses 50% less electricity…
Payback is generally less than 1 year if a VFD is installed and motor speed is reduced at least 20%…
Note that even at slightly reduced speed a motor operating with a VFD generates significant savings…
Example: The annual energy cost of operating a 20Hp motor (at $0.08/kwh) is $10,500. Using a VFD to reduce speed by only 10% will result in a 30% energy reduction. That amounts to over $3,000 annual savings on one 20Hp motor.
Tony Kaminski has been in the Automation and Control industry for over 25 years. Prior to his current position as the Power & Component Solutions Manager, Tony was an Industrial Control, Sensing, Safety and Drives Specialist for 10 years at Rumsey Electric.