5 Questions to Ask Yourself When Purchasing an Above NEMA Motor - HECO

Purchasing an Above NEMA motor—as in a motor that is not a standard “NEMA” electric motor—requires careful consideration. Whether you are installing a new application and need corresponding equipment, are in search of a surplus motor, or the time has come to replace your existing motor, there are several things to keep in mind when purchasing an Above NEMA electric motor.

HECO can help guide you throughout the entire process, from finding the right motor to purchasing, installing, and servicing it. Knowing five key pieces of information will make the process and whatever Above NEMA motor you end up with more suitable for your application.

Let’s begin by defining what an Above NEMA motor is.

1) What size motor do I need?

Above NEMA motors are not your everyday, on-the-shelf motors that every distributor has in stock.

Above NEMA motors, or ANEMA motors, are typically larger than 449T frame NEMA motors that have shaft heights of 11 inches or less. The smallest sized ANEMA motors start at a shaft height of 12.5 inches.

The size of the motor is dependent on the horsepower and speed that the application requires. For example, in a pumping system you might need to deliver a certain flow of water at a certain pressure. Based on the pump curve, which shows you the best efficiency point a pump operates at a certain horsepower and speed, you or the OEM will specify what size motor is required.

Whether you are looking at a pump curve, fan curve, or any load curve, understanding your application is critical to knowing what size motor you need.

2) What electrical requirements does the motor need to meet?

Once you’ve defined the power requirements for the motor to drive the application, now you need to determine what electrical requirements the motor needs to satisfy.

If this is a new application, you will have more freedom to deliver the correct voltage and current to the new motor. However, if you are replacing an existing motor, the replacement motor will need to be able to accept the existing supply voltage and current already available.

With any NEMA or ANEMA electric motor there is a certain tolerance for current and voltage that you can fall within, expanding the available electric motor replacements from exact 1-to-1 replacements to those that can accept existing voltage and current within its tolerances.

3) What mechanical requirements does the motor need to meet?

Mechanically, whether you are replacing an existing motor or finding a new one, you need to determine if the new motor will fit in the envelope that the old motor had. In most industrial situations, there is existing infrastructure such as pipes that could limit your ability to put a physically larger motor in place of the old one. As such, you need to understand the existing physical environment and the dimensions you need to work within.

Inside the existing envelope, you are going to have mounting components to fasten the motor to the existing base. Finding a replacement motor that has the same bolt pattern as the existing motor is ideal, but new bolt holes can be drilled in the base to accommodate slight differences. If the replacement motor’s bolt holes do not line up with the existing bolt holes and you can’t make modifications to the base, the cost to accommodate for the new motor will drastically increase.

Once you’ve confirmed the motor will fit in the existing envelope and bolt into the existing base, you’ll need to verify that the new motor’s shaft length will be the correct size to effectively couple to the existing application. On many motor drawings, the correct shaft length can be verified by comparing the distance from the front bolt hole to the end of the shaft of the existing motor versus the replacement.

Next, you need to check the bearings on the two motors. The replacement motor needs to have the same bearings of equal or larger size as the existing motor to ensure compatibility as different applications require different types of bearings.

There are many other mechanical specifications that need to be met to effectively replace an existing motor. Starting with these considerations will help you narrow down your options and allow vendors such as HECO to more quickly and accurately find a perfect drop-in replacement.

4) What environmental requirements does the motor need to meet?

Electric motors operate in a number of different environments, including those that are wet, dirty, or are in close proximity to hazardous materials. Electric motors are designed to withstand the environment they will operate in, with different enclosures to protect their internal components against the environmental stress to which the motor will be subjected.

Understanding what environment you need to place the electric motor in will determine what enclosure you need to look for. There are two general types of enclosures, open enclosures such as Open Drip Proof (ODP) and totally enclosed enclosures such as Totally Enclosed Fan Cooled (TEFC).

For example, if you are looking for an electric motor to be installed in a chemical plant where contaminates are a factor, it would be a good idea to select a motor with a TEFC enclosure to prevent contamination from damaging the internal components of the motor.

Beyond enclosures, you need to determine what accessories such as seals or filters are needed based on the environment you are placing the motor in. While enclosures protect the motor, a potential entry point for contaminates for totally enclosed motors is located around the shaft where the shaft exits the end bell. If the environment is harsh like in a chemical plant, it would be a good idea to place a seal around the shaft to prevent contaminants from damaging the motor.

If you are replacing an existing electric motor, you will want to find a replacement with an equal or greater level of environmental protection than the one you are replacing.

5) What vendor attributes should you look for?

Beyond the characteristics of the electric motor you are looking for, it’s important to consider the attributes of the vendor supplying the motor.

While price and lead time are important things to consider, there are other factors you need to take into account when selecting an electric motor vendor. These other considerations can have a significant impact on whether the motor will end up being the most reliable motor for your application.

When you are in the quoting process for a new or replacement ANEMA motor, you should be asking for motor drawings and factory performance data to confirm the mechanical, electrical, and environmental fit of the motor. You do not want to risk investing significant money into a motor without confirming the motor’s attributes.

Furthermore, while you can take all the mechanical, electrical, and environmental factors into consideration and choose a motor whose specifications fits your application, it’s imperative to select a motor vendor or manufacturer that has a proven track record of manufacturing/supplying reliable ANEMA motors that are similar in size to the motor you are looking for.

Choosing the correct motor vendor that will offer you the best options for your application is critical in the procurement or replacement process.

All Systems Go

Knowing what to ask for in your search for a large electric motor may seem like a lot of legwork, but it will pay off in the end.

We just happen to know a really good supplier of large electric motors who can help you answer the required questions, compare available options, and get your application up and running!

HECO has been in business since 1959, bringing decades of experience and expertise to servicing, selling, monitoring, and storing electric motors and rotating equipment to each project.

Contact us to put our expertise to work for you, your electric motor systems, and your processes.

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