Are Your Motors Energy Efficient?
November 15, 2023
Motors are built to last, with many of them remaining in operation for decades. But how much are they contributing to your electric bill? If your motor is older than 20 years, the answer is probably a lot.
Since motors last such a long time, the most efficient models will save more—sometimes much more—over the lifetime of the motor. According to the US Department of Energy’s sourcebook for improving motor and drive system performance, a motor’s purchase price represents just two and a half percent of its overall cost, with its electricity consumption accounting for the rest.
For this reason, it’s important to evaluate the lifetime energy cost of a motor, rather than its purchase price only.
Here are more tips on how to save energy and money on your motors.
Think twice before rewinding
When motors fail, companies usually scramble to minimize production delays. In some cases, they can choose whether to replace the motor or rewind it.
Rewinding the motor may seem like an efficient use of resources, as it will likely operate more efficiently than it did before it failed. However, it will still perform less efficiently (by approximately one to two percent) than it did when new, and much less efficiently compared to a modern, new motor.
If you can avoid using the machine or system while you get a new motor, it’s usually worth it. You’ll save substantially over the life of the replacement motor compared with rewinding the old one.
Ask for an efficient replacement
Nine out of ten times, manufacturers replace a failed motor with the same model they had before. This could be a substantial energy efficiency gain since new motors are much more efficient.
However, it’s worth asking your supplier if they have a more efficient replacement available. The minimal cost difference will quickly pay for itself.
For those looking to go above and beyond toward operational savings or decarbonization goals, consider replacing your motors with higher-efficiency models. These “super-e” motors are more expensive than standard models but are certified to perform above the energy efficiency standard set by the National Electrical Manufacturers Association (NEMA).
Motor controls do one of three things: turn the motor on, turn it off, or slow it down. In an industrial setting, there is almost always an opportunity to use controls to reduce a motor’s energy use and its wear and tear.
For example, if a facility has a conveyor belt running constantly, they can set up a control using a trip lever to stop the conveyor belt when there isn’t a product on it. This simple motor control helped one Efficiency Smart customer achieve 50 percent savings on the energy usage of the conveyor system.
Another example is a cooling tower, which lowers the temperature of water by blowing air across it with a fan. When it is fifty degrees outside, businesses don’t need their fans to run full bore to cool the water. Instead, they can install variable frequency drives to run their cooling tower fans at different speeds based on outside air temperature. You can similarly consider adding a variable frequency drive to pumps and fans in HVAC applications.
Please note: There are instances where installing a variable frequency drive on motors can slow them down. Reach out to Efficiency Smart to identify whether a control is appropriate for your motor application.
A note on smaller motors
Motors that use less than one horsepower may be good candidates for electronically commutated motors (ECMs). Two good examples are refrigeration and fan coil units, such as those found in hotel HVAC systems or at grocery and convenience stores.
Because many of these smaller fan motors run all the time, replacing them with ultra-efficient ECMs can easily halve their energy consumption.
Questions? Reach out!
Efficiency Smart helps manufacturers identify and assess energy efficiency upgrades to meet a wide range of business goals. We also provide rebates and technical guidance to help you complete projects.
For questions or to get started, contact your local account manager or our customer service team at (877) 889-3777 or [email protected].