Advantages of a DC to AC Motor Conversion

On this episode, host Mike Murphy is joined by not one, but two guests - Scott Wilcox, product specialist for DC motors and Hydro-Cool XT, and Ray Hatcher, product specialist for laminated frame motors. Listen in as the trio discusses the advantages of AC motors, the process for making the DC to AC motor conversion, and general motor tips!

Learn more about the advantages of DC-to-AC motor conversion

Transcript

Mike Murphy: 0:00

At the time of publishing this podcast, we regret to inform you of the passing of Ray Hatcher. Prior to working with ABB Ray served his country as a Marine, obtaining the rank of sergeant. I personally have worked with Ray for several years, and will go to him with many technical questions, just like the ones we'll be speaking on today. He was always glad to help and answered in ways that were easy to understand. Ray will always be a part of the ABB family. Hello, listeners, and welcome to the ABB solutions podcast, where we talk about issues facing the industry. I'm your host, Mike Murphy, speaking to you from Greenville, South Carolina a huge topic today. One I'm sure you will find valuable and one that impacts several industries and applications. But before we get to it, let me first introduce our product experts. I'm excited to have with me today. Scott Wilcox, product specialist for DC motors, and hydropool X t and Ray Hatcher, product specialist for laminated frame motors. Welcome Scott and Ray.

Unknown: 1:13

Good morning. How are you today?

Mike Murphy: 1:16

Great. It's great having you guys. So both are with me today to talk about what to look for when converting existing DC motors over to AC DC motors have been around since the 19th century, and have helped shifted us into a new industrial revolution. Traditionally, DC motors have been the choice when speed and torque control are critical. But we're now seeing advances in AC motors, along with Dr. technologies that make facilities think twice about switching their DC motor applications over to AC. So this podcast will go over some of the things to consider before making this change. Let's go over some of the common questions to avoid any gotchas. Because I'm sure it's a bit more complicated than just changing one motor out for another. So Scott, I'm going to start with you. First, why would a customer want to make the change from DC to AC?

Unknown: 2:05

Well, one of the main concerns about DC motors is the amount of maintenance they're continually needing, you know, maintenance with the brushes, the commutators, the filters best for the debris from the brushes. It's an ongoing battle. Inverter duty motors are more efficient by design, because they reduce the energy footprint, reducing the overall cost of their motors, that less downtime because you don't have the maintenance on brushes and commutators to continually fight with. But one of the biggest gotchas is ensuring during your design electrical design, to make sure you've got enough torque covered because some DC motors have higher torques at lower speeds and a standard AC motor design. So that's something you want to make sure you cover that when you're first looking at a customer's design. From there on, it's just easy to change.

Mike Murphy: 2:51

Okay, great. So Ray, I'm going to switch over to you what are some of the initial questions to have with end users before making the change?

Unknown: 3:00

Well, Michael, The first thing to consider for the customer, when you're changing from DC to AC, is that as you alluded to this is not simply just changing one motor to the other, you're making a change of the entire system. So in the case of a DC motor, you have the DC drive, the DC motor, the associated wiring, and any feedback that's that's tied into the drive or the motor, so the drive may be tied into a larger control system for a particular machine. When you're going to switch that system from DC to AC, you need to look at and consider the fact that you're switching the entire system. So you have to take into consideration that not only the drive and the motor, but the interconnecting wiring, and any changes to the machine or to the equipment rooms to accommodate the new drive and motor. And then any any interconnections between that drive you know larger control systems in the plant.

Mike Murphy: 3:56

Okay, Ray, I want to stick with you. I think you're touching on this, but let's dive a bit deeper. So let's go further into the installation what all else needs to be considered?

Unknown: 4:05

Well, if we start from the motor standpoint, we want to consider the difference in footprint between the original motor, and then any proposed new motor, because we have to accommodate, you know, attaching that new motor to the existing machinery. In addition, we're switching the drive out and inside the drive panel. And so we need to make sure that we have it you know the new drive is compatible with the existing power system. And then we can supply the necessary controls to operate that new drive and tie it into the existing system so that you're right there. For most people. That means that you're going to have to have some degree of drive expertise, either in house or or through a trusted subcontractor. In addition, everything needs to be interconnected. Even though you have an existing motor and drive. You're going to replace it with a new motor and drive in the same locations. That interconnecting wiring cannot be reused. used. And that's because of the wiring that's required for a DC motor is going to be two primary conductors that you know, containing the DC armature voltage, and current, and then two smaller conductors with the DC field current. For an AC motor, you're going to have three relatively large AC cables, one per phase. So it's an entirely different wiring setup. And so it's really it's a complete system, as I mentioned in my previous answer,

Mike Murphy: 5:29

okay. All right. So Scott, let me turn back over to you. Okay, so we've done the installation, right. So now what kind of savings could a customer realize, after doing all that,

Unknown: 5:38

when you look at saying, you know, depending on their actual installation costs, that's going to vary depending on what they had valuable, like Ray was talking about, and whether how much they had to get to that point. But once they've got the installation done, you know, you can help determine the actual recovery time where we created a scenario. And using very conservative numbers on 500 horsepower motor, that we showed you how you could recover the cost of the materials of the drive the new motor, and the operation, you can recover your cost in about a year on motor that size. And this is mainly because on the AC motor, you don't have the maintenance time, you don't have the downtime, you don't have to pay those guys who could go out there every month and dig into that motor and clean the brushes or measure the brushes, clean off the commutator sweep out the dust. And then there's the repairs. I mean, you don't have to do the repair on an AC motor is much, much less than a DC motor of the same size.

Mike Murphy: 6:34

Okay, and we do have a white paper out, correct?

Unknown: 6:37

Yeah, that's correct. Our white paper shows that in pretty good detail. And it's, it's a very good example of how they can say just by once they've replaced it. And after they recoup that first year, not including any bonus that they may get, or having a higher efficiency design. Because these motors are inherently inefficient. They take two power supplies around in most cases, and it's just a continual savings forever after that.

Mike Murphy: 7:01

Great. Alright, right back to you. So I've seen AC motor technology can put a user in a smaller motor. But what does that mean for the original setup? Well, typically,

Unknown: 7:11

as you point out, the AC motor is going to be smaller than the DC motor this replacement on the primary concern for the user is that they want to get that AC motor to match the shaft height of the existing DC motor. In many cases, in order to do that, you're going to have an adapter rail that what an adapter rail will do is it will match the mounting holes of the initial DC motor on the bottom side and on the top side, it'll have the mounting holes for the smaller AC motors. And the height of the rail will be equal to the difference in the shaft heights between the AC and the DC. Once you mount the shaft height, using an adapter rail, it's just a matter of being able to mount the shaft dimensions for many motors, including, you know, the RPM, RPM AC motors, we do offer shafts that are larger than standard for a given shaft height. And so that allows us some flexibility. And when it's not possible to increase the shaft height enough to do the match, and those cases the user would have to replace their coupling half or their bushings in order to make the match.

Mike Murphy: 8:15

Okay, right. I'll stick with you again. So as a follow up, so I've seen a lot of DC motors, I've known them to be blower cooled, but I also noticed the AC there's a lot of T FC or fan cooled motors out there. So is there even a blower option for AC?

Unknown: 8:29

Yes, yes, as you've noticed, a typical AC motor is totally enclosed fan cooled. But when you're looking at definite purpose variable speed AC motors like the RPM AC, this motor is designed specifically as an AC replacement to the DC motor. The RPM AC motor will have enclosure options for drip proof forcement, which is more or less a direct match for many existing DC motors. One thing that you can get with an AC motor that is typically not found with the DC motor is we can offer a totally enclosed blower cooled motor. And so one of the downsides to the DC motor is in addition to all the mess created by the motor itself and the form of brushed debris that gathers inside the motor. The big challenge with the DC motor is they're typically as you as you mentioned are open and blower cooled motor. The downside of that is if you're in a dirty environment, you have to get you have to use filters and constantly maintain those filters to keep the inside of the motor clean. When you go to an AC motor, in many cases can offer a totally enclosed motor that would have the same variable speed performance as the DC motor, but by virtue of being totally enclosed, you eliminate the risk of contaminating the interior of the motor from the application.

Mike Murphy: 9:46

Okay, yeah, all good points. All right, Scott, last question is yours. So what are the benefits are there by moving a customer over to AC?

Unknown: 9:53

Like we've I think we briefly mentioned that the repair costs of DC AC motors are going to be less If you ever have a motor that you have to remove, and replace it, it's going to be easier and less time to replace it. AC motors are easier and usually quicker to get. But one of the biggest things that a lot of people, you'll hear him say, I need to get more power out of my line, Can I upgrade to a higher power, they'd still use the same footprint. And a lot of times, you know, a motor may have to go up a frame size or two. Well, the beauty of this, that's the AC motor is already going to be a smaller footprint. So now we've got room to increase that horsepower for the customer and give them a larger motor in the same footprint where they were ahead though DC motor design. So now they got got room to grow their plant, they're going to save money, and they've got a lot less worry and headaches in the future. That's not to say that DC motors don't have their place for customers that still need them and can but then if there's a chance, it's always a good thing to upgrade. All right, well

Mike Murphy: 10:54

said, Hey, I think that's a great place to stop Scott and Ray. Hey, it was great having you both on I'm sure our listeners will certainly take away some great information.

Unknown: 11:02

Thank you. Thank you for having us. Thanks, Mike. Appreciate your help.

Mike Murphy: 11:05

Yeah. Thanks, guys. All right. Remember, if you'd like more information on DC or AC motors, contact your local ABB sales representative or visit us@www.abb.com And I hope you keep tuning in to the ABB solutions podcast in your Favorite Browser. Thanks, everyone. Have a great rest of your day.

Unknown: 11:24

This podcast episode is dedicated to the memory of our friend and colleague, Ray Hatcher.