Topic: Motors
EC Motor Fundamentals: What is an EC Motor and the Benefits it Offers
by Greg Allen |

The demand for highly efficient and reliable HVAC equipment continues to grow. Rising energy costs and pressure to minimize downtime have caused the HVAC industry to find better motor solutions to power fans. The electronically commutated (EC) motor is one solution, offering improved reliability and efficiency that traditional motor options cannot provide. EC motors have been around for more than 30 years but have gained increasing acceptance for HVAC applications in the last decade. EC motors commutate, regulate, or reverse alternating current direction to make a direct current through electronic circuitry. This versatility allows for increased efficiency and greater speed control.

A few key features drive EC motor efficiency. For example, every motor type has two magnetic fields. One field is in the rotor and the other is in the stator. Some motors require electricity for both magnetic fields. EC motors achieve efficiency by using electricity for only one magnetic field because of the EC’s use of a permanent magnet rotor. This reduction in electricity improves efficiency. Partial load conditions are a challenge for most motors. However, an EC motor like Greenheck’s Vari-Green® offers an integral control board. The control board monitors the load continuously to adjust energy consumption, increasing or reducing it as needed. This monitoring results in highly efficient energy use in partial load conditions. Induction motors have no such capability without additional equipment.

Additional Features of an EC Motor
The EC motor offers many other advantages that include:

  • No drive loss
  • Minimal maintenance
  • Ultra-quiet condenser fans
  • Less noise
  • Less vibration
  • Lighter weight product

If the EC motor has any real disadvantages, it is that many EC motors require an external device to regulate the fan speed. However, the Vari-Green offers a built-in variable frequency drive (VFD), eliminating the need for an external VFD. The Vari-Green also allows speed adjustments from a control, remote dial, or as part of a building management system. Stated in simple terms, an EC motor offers more advantages when compared to traditional motors used with fan equipment with none of the disadvantages.


Motor Sizes
EC motor sizes vary by manufacturer. Some manufacturers only have a few EC offerings. However, Greenheck offers EC motors in sizes ranging from 1/15th hp to 2 hp in a single-phase version and three-phase EC motors from 1 hp up to 10 hp. Companies continue to develop larger EC motors and increase fan efficiency in more products.

Reliability remains an important part of HVAC fan applications, along with energy efficiency, especially as demands for better indoor air quality increase. Most EC motors have a low failure rate of less than one percent. Greenheck’s Vari-Green motor, with more than one-half million sold since its debut in 2009, fall into the less than one percent category. An important reason is the capability to run cooler at reduced speeds. Lower temperature leads to longer product life.

Some people think EC motors are expensive when compared to traditional motor options. This belief is not necessarily true. For example, an EC motor can have a first cost that is very competitive compared to a belt drive fan. The difference frequently is plus or minus 10% of a belt drive fan. A direct drive fan with a standard motor appears to cost less until you realize you need an external device to adjust speed. The real difference is evident in the operating cost of the product. Greenheck’s Vari-Green EC motor can reduce operating costs by between 30% and 50% depending on the operating conditions. Functions including a turndown capability (80% of the maximum RPM) allow the Vari-Green to control speeds while using less energy without requiring an external device.

EC motor use continues to grow as new features and larger sizes become available. Read more about Greenheck’s Vari-Green EC motor and discover the benefits available for many fan applications. https://www.greenheck.com/vari-green/vari-green-motors


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Greg Allen
Greg Allen
Greg Allen
Greg Allen is an Application Engineer II at Greenheck and also serves as an instructor for Greenheck’s HVAC University. He holds a bachelor’s degree in mechanical engineering from the University of Wisconsin-Platteville and is a member of several professional organizations including ASHRAE.
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