Solutions Podcast Series
Solutions Podcast Series
Misconceptions Between NEMA and IEC Efficiencies
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In this episode, host Mike Murphy is joined by Mark Gmitro, Global Product Manager for Specialty AC Motors, to discuss the difference between NEMA and IEC efficiencies and clear up any common misconceptions.
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Welcome again to another episode of The ABB Solutions Podcast where we speak with experts on concerns faced in the industry. I'm your host, Mike Murphy speaking you from Greenville, South Carolina. I'm excited to have with me today, Mark Gmitro, Global Product Manager for Specialty AC motors. Mark has 32 years in the industry. I asked Mark to come speak on the Differences Between NEMA and IEC Motor Efficiencies to clear up any common misconceptions. So Mark first, can you walk us through the different levels or classes of efficiencies and and how NEMA and IEC relate to each other?
Mark Gmitro:Oh, sure. And thanks for having me join today. It's a pleasure to talk to you, Mike. First off, just a little bit of clarification. The NEMA stands for the National Electrical Manufacturing Association. And it sets the standards for motors used in North America and has been doing that since 1926. Regularly publishes updates in their specification book, which is NEMA MG1. So when you're looking for specifications and standards, according to NEMA - it's the NEMA MG Standards. The IEC is the International Electrotechnical Commission and it defines standards for pretty much motors around the rest of the world, whereas NEMA is North America. It's similar to NEMA, but a little bit different. It publishes its standards under a standards book, which is defined as 60034-1. So again, in NEMA it's MG-1 and in IEC it's 60034-1. There's a little bit of philosophical differences between the two organizations. NEMA tends to emphasize more robust designs for broader application focus. So usually there's more service factor, a little bit more fudge factor in the NEMA designs. IEC is a lot more precise in its application and performance focus. So it takes a little bit more technical knowledge about the application, including motor load, duty cycle, and etc. But fundamentally, they both do the same thing. They're there to define efficiency classifications in standards. The latest NEMA standard is MG10, actually, published in 2017. And defines efficiency classes for direct across the line motors. So both IEC and NEMA define motor efficiencies for motors that run across an AC line and they NEMA there's standard efficient, high efficient, premium energy efficient motors, and superpremium motors. And really, the DOE, the Department of Energy, has already mandated or standardized around high efficiency motors. So you really don't buy standard efficient motors today. Then in the IEC world, which again is that 60034-30-1. Latest publication was in 2014. The correlation is they're called an IE scale. So IE1, IE2, IE3 ,and IE4. And those line up with standard efficient, high efficient, premium, efficient, and superpremium. Right now, IEC will be putting in standards for motors next year that actually require up to IE4 levels. So you're asking, well, what's the difference between each of those efficiency classes? Really each step of efficiency class, the motor has to have 20% less losses. And those losses are produced by you know, electrical losses and mechanical losses in the motor. And if you reduce the losses, the efficiency goes up, because losses are just wasted energy. So each class of efficiency, you have to reduce the losses in the motor by 20%. And that's how you can get to higher efficiency levels. And then so one last thing that IEC actually specifies, so you have to look at standards that are codified and specified for motors, and that's MG10 and the-30-1 for IEC. But then there's guidelines, they're not codified standards, but they're guidelines, if we did this. And one of those technical standards that are called in IEC is again that 60034-30-2. And what it does is it provides well if we provide we've created a standard across motors that can only run on a drive and they don't run across the line, what would that look like? So that's what the 30-2 attempts to do. They're for permanent magnet motors and synchronous reluctance motors that can only run across a drive and don't run across the line. And so they define efficiencies for those types of motors and what that might look like.
Mike Murphy:Okay, so you are saying the efficiency standards would differ, depending on if the motors running across the line or ran by a VFD?
Mark Gmitro:Technically, yes. When you run a motor across the drive, the technical standard allows for additional losses in the motor, so it's easier for that motor to make efficiency classes, because for example, below 90 kilowatt, or about 125 horsepower, the motor can actually have 15% more losses than a direct across the line motor. So instead of you know, jumping up 20%, in efficiency, I mean, 20% less than losses, you get a 15% allowance, so it makes it easier to get to the higher efficiency classes. But, we don't really define motors that way. We define them as if they run across the line, even if it's a motor that has to run across a drive. And if you ask why. That's because we're in NEMA, or in North America. And NEMA MG10 has no technical standard like IEC does for motors that only run across drives. So every time you look at a Baldor motor, whether it's a synchronous reluctance motor, Okay. And again, I'm picturing a Baldor-Reliance nameplate right whether it's a permanent magnet motor, even though it has to run on a drive, we rate it as if it runs direct across the line because we stamp that motor per NEMA standards. And since NEMA doesn't define motors that only run on drives, at least not now. And it says like nominal efficiency, correct?Does that today, that's why we do it that way. But when you get into the IEC world, it's a little more gray. They have direct across line and motor standards and this 30-2 standard for drives. also include like full load; if the motor is fully loaded? Correct. So that's NEMA nominal efficiencies at full load and full speed, correct. And that's actually a decent point. Because, you know, I said that that IEC technical standard allows for more losses in the motor. It also limits the value to 90% speed and 100% torque. So that makes that efficiency calculation a lot different than you know how we rate NEMA nominal at 100% speed and 100% load.
Mike Murphy:Okay. A little bit ago, you mentioned something about the energy losses, some can be electrical, some can be mechanical. Can you expand on that a little bit? Where are these losses typically coming from, out of a motor?
Mark Gmitro:Well, you have basically losses come from a motor in three or four primary ways, some of which you can impact some of which you can't really. So you know, and you say, well, what do you mean, you can't impact the efficiency losses? Well, one of them one of those is mechanical - it's bearing frictional, losses and windage from the fan. And you can do some, some design things, but it's it makes a nominal contribution to your efficiency losses in the motor. And then you have core losses in the frame and the steel of the motor. You can go to better electrical steel, you can go to different higher grade steel lamination and annealing process to reduce the losses in the stator and rotor core, and things like that. But again, that's not usually where people are focusing on losses in the motor to increase efficiency, because a big part of your losses really come from the stator winding, and those are just I2R [I squared R] losses. So it's just you put current through a wire, it has a resistance to it, and you get you know, heating and losses just like when you turn on a light bulb. So, you can you can go to more active material in the motor, more copper and that reduces the losses in the stator. So, a lot of times people will simply go to you know, a larger heavier motor, because then I have more active material in there and and get more copper in the stator windings and reduce the losses in the stator winding. So that's one way to do it. The other is you have rotor losses. So, all induction motors have a solid core rotor and you have losses in that rotor. You know you induce a magnetic field in the rotor through the stator magnetic field, which produces a current and but that causes circulating losses in the rotor, and you get I2R losses in that in that rotor that aren't doing any work. So primarily, when you look at high efficiency motors, they're either focusing on the rotor losses, or the stator stator losses. But when you look at, you know, NEMA premium, super premium motors, really what they're doing is addressing the stator winding losses and, and putting more active material in that, more copper. But you know, it's a finite limit to how much you can only make the motors, but so much material into a, into a standard frame induction motor without over sizing it, then you're not following the NEMA standards for frame sizes.
Mike Murphy:Sure, sure. Okay, that makes sense. So that's kind of where some of these top tier motor manufacturers are focusing in on to to meet these standards correct, like these premium super premium standards, or say, IE4, IE5. Okay, they're focusing in on those better, better conductive materials better, better stator windings? Okay. Mark, I've seen online, there's some companies out there reporting, IE6 efficiencies. Help me understand this, how are they even able to do that?
Mark Gmitro:Well, there's there's a couple of ways. So, you know, let's, let's go back and revisit, how do I get first off before, like, how do I get to IE5 and IE6 levels, if I just said the stator winding, you can only put so much active material in there and reduce the losses only so much. So one of the ways you do it is you add magnets to the motor. And so what a magnet does is it does part of the work of the stator. So, you know, it depends on the magnet design, but a lot of times like the magnets will do about 30% of the work of the stator. And that means that the stator winding doesn't have to work as hard. And if it doesn't have to work as hard, it's not drawing as much current, because the magnets are actually producing torque in the motor, not the stator. And that increases the efficiency of the motor. So and then the if you go to really strong magnets, like the rare earth magnets, the neodymium boron iron magnets, it can even do more of the work of the stator and further reduce the losses. Those tend to be rather expensive. And due to volatility in the commodity market, and supply chain, sometimes they're not as readily accessible. But you can boost a motor to fairly high efficiency simply by doing that. But then again, also remember what I just said about the IEC standard. So if I go to a permanent magnet motor, it cannot run across the line and most of the world is on the IEC standard. So when you see IE6 out there, a lot of it's coming from the international community. And they're not wrong, but they're not reading that motor as if it runs across the line. And so you remember I said you could have 15% additional losses in that motor that aren't accounted for. So that makes getting to IEC a lot easier. And if you looked at a lot of let's say the Titanium motor from Baldor, that's rated IE5+. If I went ahead and did the math, and said okay, I'm going to rate this as IEC standard against the 60034-30-2 spec that allows for additional losses, the EC Titanium is practically IE6. And as a matter of fact, it is IE6 for all of, all the rating, except maybe one horse, the one horsepower unit, which is you know, a smaller frame motor. But that's how they're doing it, you know, but it's not from an equivalent efficiency standpoint. It's not like they're better than a NEMA design motor, they're just held to a lower standard on the IEC scale, because it allows for additional losses in the motor. So that's that's one way they're doing it. The other way you can do it is you can go to a no loss rotor design. Remember I said uh, you know, you have losses in the rotor, it's about 20% of the losses in the motor. If I can go to a no loss rotor design, that gets me up a class of efficiency. So when you look at the EC Titanium, what we actually did is we combined both magnets, and the no loss rotor design to get you above IE5 efficiency by reducing 20% of the losses of the stator with the magnets and 20% of the losses of the rotor go into - it's called a synchronous reluctance rotor, but it basically think of it as a no loss rotor - and so that's that gets you from your NEMA premium to super premium with the magnets. And then IE5 with the synchronous reluctance rotor design. So that's that's how you're doing it. But that's how other people are reporting IE6. Technically, we could probably do the same, but again, remember, we're NEMA, so we're still trying to hold on to as if this motor could run across the line, even though it can't. Right. That's what we put on the nameplate. So that's why we put it in as IE5 only because we're making the assumption, just a flat loss assumption based on as if the motor could run across the line. And then when people are reporting IE6, they're using that IEC standard, which is the international community and it's easier to achieve higher efficiency. Now, you know, if you put them side by side the equivalent efficiencies would be about the same with their IE6 product is about equivalent to an IE5 as if it was running across the line.
Mike Murphy:So it's good to speak apples to apples when when compare the motors. And just as just a side note, Mark did mention the Baldor-Reliance EC titanium. But he did, was in on the ground floor, right Mark on the development of the of that motor. Mark, I got one last question for you. Where do you see motor efficiency going in the future?
Mark Gmitro:Well, where I'm seeing motor efficiency moving forward is I think you're gonna see, you know, finite gains above where we are right now. There's only so much you can do with, you know, adding magnets to the motor, or going to a no loss rotor, adding active material to the motor, right? You might be able to tweak it a little bit above, you know, some of the designs you see out today, but you're going to, you know, make a larger, heavier motor or product that's unreasonable from a cost effective standpoint so that you know, the price will go up. But what I really see efficiency going in the future is system efficiency. So when you look at where efficiency standards are moving, they are more focused on the overall system design. So instead of saying, your motor efficiency has to be 94%, they're coming back and saying your fan or your pump system has to be above this minimum efficiency. And then we're just a component of that. And so what you want is a flexible motor design that maintains its efficiency across a broad load and speed profile. So that pump or that fan OEM can optimize their design and always be guaranteed the motor efficiency is staying high. So they can maximize their overall pump or fan system efficiency to meet some of these new emergence merging regulations. So like here in the US, it's not the DOE. But if you go state by state, you know, California always seems to lead with these efficiency standards. There's a new emerging standards coming out around pump systems for pool pumps. And so again, the pool pump manufacturers are having to now redesign their pool pumps to meet these new efficiency standards. But it's much less around the individual components. They are being mandated, your pool pump has to meet this efficiency. And so that comes down to their impeller design, their pump design and the motor. And that's where efficiency is going to go in the future. Because, you know, the reality of it. The most inefficient thing in the system is the pump or the fan design, not so much the motor, right? We can do things to help achieve that system efficiency and optimize our designs. But you know, ultimately, that's that's where efficiency is moving to in the future.
Mike Murphy:Okay, great. All right. So that's a great place to stop. But Mark, this is fantastic stuff. Hey, thanks so much for speaking with me today on Efficiency Differences Between NEMA and IEC. Remember, yeah, thank you. Remember, if you'd like more information on choosing the right efficient motor for any application, such as the Baldor-Reliance EC Titanium or the ABB SynRM motor, contact your local ABB sales representative or visit us at www.abb.com, then under the Products tab, select motors and generators. And as always find our podcast by searching ABB Solutions Podcast in your favorite browser. Thanks and have a great rest of your day.
