Do you have questions about EC motors? Below you will find several frequently asked questions about electronically commutated motors and their accessories. We have tailored this FAQs to help engineers, procurement managers, and service managers find what they need regarding our products, but if you can’t find the answer you want, feel free to contact us.
EC (Electronically Commuted or Electronically Controlled) motors are electric motors which have permanent magnets on the rotor, and use electronics to control the voltage and current applied to the motor.
All electric motors work by the interaction of two magnetic fields pushing on each other. One field is created by the rotor, and one by the stator. The difference between motor types is in how these fields are created and controlled:
- EC motors use permanent magnets to create the rotor field, and a series of coils controlled by an electronic controller (or “commutator”) to create the stator field.
- Brushed DC motors use permanent magnets to create the stator field, and a series of coils powered by the DC input voltage and controlled by mechanical contacts (“brushes”) to create the rotor field.
- Induction motors use a series of coils powered and controlled by the AC input voltage to create the stator field, and the rotor field is created electromagnetically (or “induced”) by the stator field.
EC motors have no brushes, and so avoid the sparking and short lifespans that are more common of brushed motors. Because they have electronics controlling the stator, and do not need to waste power inducing the rotor field, they give better performance and controllability, and run cooler than induction motors (for small motors, at least: high horsepower 3 phase induction motors can be very efficient).
EC motors are used today in many fractional-horsepower applications, wherein high motor efficiency, reliability, and/or controllability is desired.
Terminology in the motor world is confusing, as many acronyms are used for the same thing, and people’s definitions are not always consistent. For all practical purposes, many of these terms are interchangeable.
- EC stands for Electronically Commutated. ECM stands for Electronically Commutated Motor. These are the same thing, and usually refer to motors which use AC mains power.
- BLDC stands for Brushless Direct Current motor: a BLDC motor may be the same as an EC motor, but it is more often used to refer to an electronically controlled motor which uses a DC power supply.
- PMSM stands for Permanent Magnet Synchronous Motor. Often this means the same thing as a BLDC motor, although in academic circles the two terms are sometimes used to distinguish between motors with different types of commutation algorithms.
- VFD, which stands for Variable Frequency Drive, is the one term which means something significantly different. A VFD is a type of electronic controller which is used to give an induction motor (usually a larger, 3 phase motor) improved controllability and part-load performance. Although VFD electronics are similar to those of an EC motor controller, the software is quite different and the two are not interchangeable.
EC motors have very high efficiency, and maintain a high-efficiency level at partial speed. This means that in most cases they use less than one third to one half of the electricity used by the traditional motors used in the ventilation and refrigeration industries. This translates into lower operating costs and short payback periods.
EC motor’s high efficiency also means that the motors run “cooler”, and dramatically reduce the amount of waste heat produced. Reduced waste heat at the evaporator motor level also typically results in reduced operation at the compressor level, which allows even further energy savings. Furthermore, running cooler improves the life of highly loaded motor parts, like windings and bearings.
EC motors also have a wider operating range than traditional induction motors, which means that one ECM motor can replace numerous induction motor models. In this way, the number of models required by a typical customer is significantly decreased, which decreases and simplifies inventory. This is the main reason why ECM product lines usually include less motor models than their induction counterparts.
In terms of speed control and features, because the motor’s operation is controlled by software, EC motors allow customers to optimize and integrate the motor, fan and controller with applications. This enables features like data communications, constant volume control, variable speed, etc.
EC motors are also quieter than traditional motors, have longer design life, and require less maintenance.
Efficiency varies depending on the manufacturer, power rating and each application’s conditions. However, as a general rule of thumb, shaded pole motors range from 15-25% efficiency, permanent split capacitor motors range from 30-50% efficiency, and EC motors achieve 60-75% efficiency.
After the compressor, refrigeration fans are one of the highest energy consumers in an HVAC or refrigeration product. Improving motor efficiency by using EC motors is one of the most cost-effective “bolt on” efficiency upgrades available, offering a similar advantage as changing to LED lighting. On a typical glass-front upright self-contained (plug-in) cabinet, upgrading to EC motors improves overall system efficiency by 20-25%.
Not all EC motors are suitable for use with hydrocarbon refrigerants, or for use in all applications. AoFrio offers “HC compatible” versions of our ECR® refrigeration fan motors, which are “non-sparking” per UL requirements, and approved for use with hydrocarbon refrigerant charges up to 150gm. For more safety-critical applications, we also offer ATEX certified (EEx nA IIA T5) versions of ECR motors. For assistance selecting the correct motor for your hydrocarbon application, please contact us.
Payback analysis involves many factors, such as your local electricity rate, duty cycle of the motors, efficiency of the air mover, and operating conditions. For high-duty cycle applications, such as refrigeration fans, payback can be as short as a few months. For low duty applications, energy savings may not be the driver for moving to EC motors. We’d love to hear about your application, so please contact us to discuss further.
EC motor pricing varies by features, size, and volume. In general, expect to pay anywhere from two-to-four-times the price of an equivalent size AC motor. Our products are very competitively priced, and we’d love to hear about your needs, so please contact us to discuss further.
No. Because EC motor electronics convert incoming 50 or 60 Hz AC power to a DC voltage within the motor, the speed of the motor will be the same with 50 or 60 Hz AC power input (except in the case of ECR 82/92 motors, which are “mains synchronous”).
No. The “hum” you might be hearing with an AC motor is likely the noise produced from the resonance of the motor lamination stack when you speed reduce an AC motor with a TRIAC, voltage chopper, or some other phase chopping device. The noise tends to become more prevalent as the speed is reduced more. The heat generated from altering the sine wave to a chopped waveform also creates additional temperature rise in the motor, leading to shorter motor life.
Engineers are occasionally asked to predict average motor life or mean time between failures for a given motor.
The life expectancy will depend strongly on:
- ambient temperature;
- motor load;
- number of starts;
- grid voltage conditions.
Wellington motors are designed for 10+ years of life under nominal operating conditions.
AoFrio defines rotation looking directly at the blade.
Some motors are known to either burn out or take themselves offline to avoid damage. Wellington’s ECR 2 motor has a unique foldback capability that automatically reduces its speed to maintain airflow without going offline. This enables the ECR 2 to operate longer while overloaded, without causing permanent damage to the motor. While we always recommend proper system maintenance and promptly addressing overload conditions, this capability keeps the cooling system online longer, preserving product quality and profitability.
Yes. A motor’s ability to keep out water, dust, or debris is determined by its enclosure rating. These ratings are defined by IEC standard 60529, with higher numbers corresponding to greater levels of protection. Wellington’s ECR 2 motors feature an IP67 level of protection. This means it is dust-proof and can operate while immersed in up to 1m of water for up to 30 minutes. To learn more about IP enclosure ratings, check out this free white paper here.
AoFrio has a wealth of technical drawings, wiring diagrams, performance data, and comparative performance curves that show how our motors perform against many competitors in a variety of applications. We have our own state-of-the-art testing facilities and are proud to partner with one of the best universities in the world for independent testing and verification. Please contact us to request any desired information.
The operating voltage range for ECR motors is shown on the motor’s datasheet. ECR motors typically withstand (but are not guaranteed for) sustained voltages up to maximum operating voltage +10%. In the case of ECR 2 motors when used in 115V markets, this gives an overhead of more than 150V. All ECR motors will withstand voltages as low as 0V – unlike induction motors, ECR motors cannot be damaged by undervoltage: they simply turn off when the voltage is too low.
ECR motors typically withstand voltage surges of up to 500V, as they are designed to meet “Industrial” immunity standards (as defined in IEC61000—6-2), rather than the less severe “commercial” standards. Wellington’s ECR motors withstand fast transients (spikes) of up to 4000V, which is twice that required by IEC^1000-6-2.
The warranty coverage depends on the terms and conditions agreed with the equipment manufacturer. Contact your OEM or AoFrio representative for specific information.
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