Understand the benefits & differences in Above NEMA motors
You’ve recently received word that one of your larger electric motors -- the technician or repair described it as an "Above NEMA motor" -- is going to have to be replaced. Before you start requesting bids on it, however, you’d like to know a bit more about what you’re getting into. What is an Above NEMA motor? What kind of information do you need to request a bid or find one to purchase? How much will it cost? And where is the best place to purchase one?
NEMA stands for National Electrical Manufacturer Association, and most standard electric motors are based on NEMA frame sizes and specifications. The frame designation and suffix can tell you a great deal about an electric motor, including the exterior dimensions of the motor for mounting but also the location of the shaft relative to the base, where the bolts are located, and the length and diameter of the shaft.
Large electric motors (those of 400HP or more, Siemens manufactures them up to 18,000 hp in the USA) and medium to high voltage motors are typically referred to as Above-NEMA, ANEMA, A NEMA, or A-NEMA electric motors. The term “Above NEMA” refers to the fact that there is not a NEMA frame to match these motors -- their frames and specifications are not regulated and consistent like NEMA frames are. They do not adhere to standard NEMA frame sizes because they are usually manufactured for a specific application or to specific customer requirements as opposed to general use. This can make them more difficult to find a drop-in replacement for.
Investing in a new Above NEMA motor is a big deal, so there are some things to keep in mind before you make that purchase. For example, before you invest in a new motor, take time to figure out why the old motor needs to be replaced. It could be that the original motor simply went past its useful life.
However, if that is not the case then you will save money and downtime by figuring out why it failed before you buy a new one. Failure to do so could result in repeating the same mistakes again with a new motor. Some common reasons for motors to fail, besides wear and tear, could be that it was not the correct horsepower for the application, or the enclosure was not appropriate for the environment it worked in, or perhaps it was on a VFD (variable frequency drive).
In order to make sure that you do get the correct motor, here are some necessary specifications for requesting a bid on an Above NEMA Motor:
Most of this information can be found on the electric motor’s nameplate. Here are some other parameters and requirements to keep in mind as you begin requesting bids for a replacement motor:
There are also specifications that you can require manufacturers to meet in connection with your new Above NEMA electric motor, including these:
The price of an industrial electric motor depends on the size rating, speed, input voltage, frame size, and whether it is a specialty motor. In general, the larger the output, the higher the price; the larger the frame size, the higher the price. Because Above NEMA motors are usually classified as large, medium or high voltage motors, they will cost significantly more than a standard, lower horsepower NEMA motor.
One of the best ways to purchase an Above NEMA Motor if you need it quickly or for less money is to consider a surplus motor. Many times you can purchase a surplus Above NEMA motor, completely rebuilt and 100% warrantied for 20-40% less than a new one. This is also many times at a fraction of the lead time. However, there are some risks in purchasing surplus motors and you need to make sure you are buying them from a credible source.
You have several options as to where to purchase an electric motor: online (which is risky -- you can easily get scammed or get a very poor quality motor), power transmission shop or bearing supplier (but they likely won’t have quick access to Above NEMA motors), or direct from the manufacturer (which can actually be more expensive than purchasing from a distributor), or from an EASA motor repair shop (which is going to be very familiar with motors). The benefit of purchasing from an EASA repair shop is that their experience in troubleshooting and repairing motors gives them additional insight into how motors work in different applications. That insight can be to your benefit, especially when shopping for an Above NEMA motor.
HECO is an EASA certified repair shop, but we are far more than just your ordinary electric motor repair shop. We develop and implement predictive maintenance plans, run vibration analysis, perform troubleshooting and repairs, and we also sell new motors, including NEMA and Above NEMA motors.
Looking for a new provider for your electric motor maintenance? Select wisely
Selecting the right motor, with the right specs for your application is critical to keep your costs at a minimum.
Once the right motor is selected Reliability Maintenance is critical to keep your costs down...and in good graces with the boss. Get to know HECO's MAPPS (Motor And Powertrain Performance Systems) system to ensure All Systems Go
Keep your career on track with continuous learning. Subscribe to HECO's informative blog, Here You Go
Here are some blog articles from HECO's blog, Here You Go, that might be helpful:
Here are some additional resources on the web related to NEMA Standards
You can also check out our Resources page for more information such as spec sheets, videos and more e-books.