Motors & Drives: Tips and tools for efficient motor management, Part 1
Michael Lyda, motor and drive engineer with Advanced Energy Corp., explains tips and tools for efficient motor management in this transcript from a December 2020 webcast.
Michael Lyda, motor and drive engineer with Advanced Energy Corp., explains tips and tools for efficient motor management in this transcript from a December 2020. Part one focuses on motor basics. This has been lightly edited for clarity.
Good day, and welcome to our webinar on tips and tools for efficient motor management, brought to you by CFE Media and Technology.
Joining us today will be Michael Lyda, motor and drive engineer with Advanced Energy Corp. I’m Kevin Parker, editor of Plant Engineering Magazine.
Michael Lyda started working for the Advanced energy motor lab in 2010 as a co-op student. After completing an engineering fellowship with Advanced Energy, Michael moved into the motor lab coordinator role in 2013. With extensive testing experience in the lab, Michael then moved into the laboratory director role in August 2019. His efforts today are devoted to motor system testing, development, research and training on a wide range of applications.
Michael is also a member of the Advanced Energy commercial and industrial team participating in energy assessments and recommending energy conservation measures at regional facilities. Michael received his bachelor’s degree in electrical and computer engineering with a minor in mathematics from North Carolina State University. Michael, welcome to today’s webinar, and please go ahead.
Michael Lyda: Today we’ll be presenting on electric motor management and variable frequency drives, commonly known as VFDs. This information is intended to help you develop or improve your motor management system and generate energy savings for your organization or even your clients.
First, I would like to say a few words on Advanced Energy. We are a nonprofit energy engineering firm created in 1980 by the North Carolina Utilities Commission. We were charged back then to investigate and implement new technologies for distributed generation, load management, conservation and energy efficiency. Over the last four decades, because 2020 was our 40th anniversary, we’ve worked closely with our clients as an independent resource for unbiased technical expertise on commercial and industrial, residential, electric vehicles, motors and drives, and renewable initiatives.
So why are motors and drives or electric motors important? Motor-driven systems are estimated to account for approximately 50% of all electricity generated in the world. Motor-driven loads likely account for a large portion of the energy bill at your facilities. Having an effective motor management system and taking advantage of energy savings opportunities with variable frequency drives can save you a lot of money over time.
I presume that’s why most of you have joined the call today, or maybe you’re like me, you need one more PDH or one more CEU before the end of the year. Either way, glad everyone’s here. We’ll be giving the presentation in four sections: motor basics, motor applications, motor management, and finally the section on variable frequency drives.
Tips & tools for efficient motor management
Part one, motor basics
What is an electric motor? An electric motor is a rotating apparatus that converts electrical power to mechanical power. Voltage and current are the inputs; torque and speed are the outputs. It’s likely that you interface with electric motors many times a day in your everyday life; at home, with your refrigerator, your washer and dryer, maybe even your HVAC system; in your car, power windows, windshield wipers.
And then of course at most of your jobs, pumps, fans, compressors, chillers, boilers, many other things that we could list off. There are many different types of electric motors. Today we’ll mainly be talking about induction motors. Although when we talk about the motor management techniques, they’re going to apply to nearly all motors. You’ll see induction motors listed on this slide in the top left. Induction partitions off to single-phase and polyphase or namely three-phase motors.
Single-phase motors will typically be found in residential or smaller agricultural applications and three-phase motors will be found in industrial and even larger commercial applications. Induction motors have been around since the 1800s. But that doesn’t mean that they’re really old news. In general, they have simple, straightforward operation and are somewhat easy to produce at high volumes. They’re also very rugged and typically pretty reliable. That’s why they’ve lasted since the 1800s.
Next we’re going to go over the different components of an induction motor. On this slide, we have rotating components from left to right. In the picture we have the shaft, the rotor, which is painted red, the rotor paddles and balancing nubs, which are shown in cast aluminum. And then the component labeled number four is the fan, which for this motor is plastic.
Next slide we have housing components. In bells on both sides of the machine, the bearing housings and stator housing, which are both painted orange here, the cooling fans on the outside of the motor, the junction box, where the motor terminals are found. It’s hard to see. It’s kind of in the back of the motor on this picture. And then finally labeled number nine will be the fan shroud and that’s used to safely guard the fan during the motor operation.
Final slide of components. We have the fixed components. So shaft seals, stator windings, stator laminations and bearings. Of course, bearings are probably the most influential component on motor life. And we will definitely be getting into that more later on down in the material. Next, we’ll see a few examples of motor nameplates. I’m not going to spend much time on this, but just to give you an idea of what you may be looking for.
Some of the more common name plate specifications will be listed on the following two slides. So here we have very important parameters on the name when we talk about the motor management techniques they apply to nearly all motors. These include horsepower, speed, voltage, and current. Each motor should also have a specific model number and serial number from the manufacturer that designates it from all of its other products.
Here are a few more parameters that you might find on the nameplate: including service factor, also called short-term overload factor; frame size, which is generally standardized across this industry, the motor industry; insulation class, which indicates the maximum allowable internal temperature; the full load running efficiency; the power factor, which is generally as a ratio of real power used to total power generated by the utility. And then finally, NEMA design letter. NEMA is the acronym for the National Electric Manufacturers Association.
It’s a trade organization of electrical equipment manufacturers in the United States. Electric motor manufacturers participate in NEMA to standardize various performance factors across the industry. The design letter is one of those. And this isn’t just for motors. NEMA isn’t just for motors, but for many different types of electrical equipment. Next, we have a display of a standard induction motor compared to a generally higher efficiency motor.
Generally speaking, an efficient motor will have more copper, more steel and most likely a smaller fan than a less efficient counterpart, although this is just generally speaking. The increase in steel and copper make the motor heavier by weight and more material means more money. A more efficient motor is typically more expensive, even if you just look at the material aspect.
Efficient motors generally will operate cooler. One common question that folks may have, how do you have a device that operates cooler when it has a smaller cooling fan on it? One of the answers, a more efficient motor will likely have a lower operating current due to lower resistance in the windings. This means the I2R power losses of the stator will be less. And then of course, lower losses leads to higher efficiency overall.