The partial load zone and SynRM, a perfect match.

Many processes don’t require the full output of an electric motor. They work in areas below full power, in an area I like to call the partial load zone.

Running motors direct on line with mechanical throttling is quickly becoming a thing of the past. We see our customers adopting drives to control their motors because they know they have options to help them save energy and reduce costs.

That’s because typically, many processes don’t require the full output speed and power of an electric motor. They work in areas below that, in an area I like to call the partial load zone.

The partial load zone

For example, pumps quite often run in the partial load zone. They typically operate anywhere from 60% to 80% capacity. Here, it’s not only drives that help save energy, your motor choice also plays a critical role. Across the lifetime of the motor, the purchase price is quite small compared to the cost of the electricity consumed by that motor. If your goal is saving energy, there’s one motor to consider that gives you the simplicity of induction motors with the efficiency of permanent magnet motors, only without the magnets. They are called synchronous reluctance (SynRM) motors. The already high (“super premium”) efficiency IE4 motors can provide something induction motors can’t – very good partial load efficiencies. So if you are running your pump constantly at 80% with induction motors and drives, you could be saving even more energy using SynRM motors and drives.

High partial load efficiencies were one of the main reasons Kolmeks chose to use the ABB SynRM motors and drive packages.

Not only for pumps

The partial load zone is not exclusive to pumps. Fans also benefit from the SynRM partial load efficiencies, but also these savings extend to constant torque applications like extruders or conveyors or even wire drawing machines.

Ecodesign standards and the partial load zone

And with the new European EN 50598-2 standard recently released, we will see a growing focus on the partial load zone. This new standard defines efficiency classifications (“IE”) for drives (called “complete drive modules” in the standard), and also for the combination of the drive and the motor into an “IES” classification. What’s very valuable is that the standard defines a series of eight operating points throughout the speed range – in the partial load zone. These points provide the efficiency of the drive and motor at each defined operating point (for example, 50% current and 50% speed). We provide this data already in our manufacturer statements that you can download now. These verified package efficiency statements  help machine builders estimate the overall energy use of their machines, or if you are doing a retrofit or upgrade, it helps you estimate your payback times. We (ABB) were actually the first manufacturer to provide this information for our customers because we feel that the partial load zone and our SynRM motors are a perfect match.

If you are interested in learning more about our SynRM motors and drive packages, I talk about four things to consider when choosing drives for SynRM, and also the importance of flying start capable drives.

Looking for more information about induction motors, permanent magnet motors and SynRM motors? Here’s an article that explains the technology and compares these motors.

Have questions? Leave me a comment below!

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About the author

Linda Stenman

I’m currently a Product Manager responsible for putting together drive and motor packages. I started working for ABB in 2008 as an Area Sales Manager for motors focusing on South Asia. During that time I got to see and learn about the value drive and motor packages give our customers. Now, SynRM packages are a main focus for me. I’m excited about the potential these packages offer our customers for energy savings and improved process performance.
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