The Next Step In The EC Motor Revolution


The desire to control motors to provide a greater efficiency for the fans,pumps, and compressors has led the industry to explore development and use of variable speed motors. Approximately 25% of world electrical energy is consumed by by electric motors in industrial applications. In heating and air conditioning industry most motors do not need to operate at full speed and they could satisfy the heating and cooling load by operating at a slower speed. For example, if a home or business needs only 50% of the its capacity of the gas furnace to satisfy the space temperature, it would be advantageous to reduce the capacity of the unit rather than stop and restart the unit. When the power consumption can be reduced in this manner, the unit becomes more efficient. Lennox Signature Collection & Elite Series systems are equipped with EC motors.

New government energy-efficiency standards, combined with advances in materials and electronics, are compelling many end users and OEMs in the heating, ventilation, air-conditioning and refrigeration industry to design—or redesign—their systems to be more energy efficient. Because blowers are one of the biggest energy consumers in an HVAC or refrigeration system, the motors that power them are “low-hanging fruit” and have been a primary target for these efficiency improvements. Over the past decade, for example, as many as 50% of all new residential furnace blowers have been upgraded with efficient electronically commutated (EC) motors. EC motors are electric motors that have brushless permanent magnets and have been integrated with a tuned variable-frequency motor drive. Because they use electronics to control the voltage and current applied to the motor, EC motors do not waste power inducing the rotor field like induction or other motor types.Until recently, however, EC motor upgrades have been performed primarily on smaller, residential applications that require motors of one horsepower or less. Advances in materials and electronics, however, are now changing all that. Switching to EC motors is today one of the most cost-effective “bolt-on” energy-efficiency upgrades that can be made to a commercial or light industrial HVAC or refrigeration system.
The transition EC motors are proving to be an especially good upgrade option for HVAC and refrigeration systems that currently depend on induction motors to power the fans, blowers and pumps that drive air and water through their systems. OEMs and end users, alike, see switching to EC motors as a way to boost their systems’ overall efficiency with one relatively easy-to-make change. EC motors are now available in an increasing number of sizes and power outputs. Some of today’s most advanced integrated EC motor and drive systems can operate up to 10 hp and have achieved or exceeded the IEC defined IE4 Super Premium efficiency rating. That makes them good candidates for those who want to capitalize on energy-rebate opportunities, as well. 

When integrated into a system, these motors not only save energy, they also can be used to create systems that are smaller, lighter and quieter to operate.

Energy savings—EC motors that meet IE4 efficiency levels have been shown to offer up to 91% system efficiency for the motor, drive and fan. In some cases, that exceeds the efficiency required by NEMA for a premium-efficient motor alone. At that level of efficiency, a single 5-hp motor can reap energy savings of between $180 and $250 a year, compared to an induction motor and VFD. Improved reliability—An integrated EC drive/motor system that has been precisely tuned can reduce common VFD-related issues, such as electromagnetic interference and corona discharge, which can produce electronic noise and disturbance. In addition, because EC motors are not prone to overheating, they do not require additional measures to offset heat generation.

What is next

The IEC IE4 super premium efficiency requirements set a high bar for the future. To reach that bar, motor manufacturers can be expected to continue extending the power outputs and other capabilities of integrated EC motors and drives, thereby expanding the range of commercial and industrial applications they can serve. Larger hydronic pumping systems, and rooftop and other commercial blower systems will be among the next to benefit. The good news is as more IE4 efficiency motors become available and all the new efficiency regulations are in place, end users will be the ultimate winners. The new, more efficient systems they will generate will consume less energy, saving money and improving overall industry performance in the long run.


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