Genteq® Evergreen® OM Outdoor Fan Motor - Multi-HP Made Easy

August 7, 2023

Motor Minute^™ Technical Tip – Evergreen® OM Outdoor Fan Motor – Multi-HP Made Easy

Hi, Chris from Regal Rexnord here with your Motor Minute technical tip. Helping you become an HVAC motor pro one minute at a time.

Today’s Motor Minute topic is Evergreen® OM outdoor fan motor, multi-horsepower made easy.

The Evergreen OM motor is an ECM outdoor fan motor designed to replace PSC motors.

ONE Evergreen OM motor stock # 6303R has the ability to replace single speed 48 frame outdoor fan motors rated:

• 1/3 – 1/10 horsepower
• 1075 and 825 RPM
• CW and CCW

One question I am often asked about the Evergreen OM motor is, how does it replace 1/3 – 1/10 HP motors with only one line voltage connection?

The Evergreen OM motor requires only three wires to operate. The black and white wires connect to either side of the contactor, and the yellow or orange wire connects with the black wire to select the RPM. Horsepower is automatically regulated due to the constant speed programming.

The Evergreen OM motor stock # 6303R is a 1/3 HP motor. However, it can replace PSC motors rated as low as 1/10 HP.

This concept is easier to comprehend if you relate the constant speed programming of the ECM motor to something you do every day, driving your service truck.

Let’s say your truck has an engine capable of producing 300 HP. If you took all of the parts and tools out and drove it at a fixed speed, say 55 MPH, you would not need all 300 HP to achieve this speed. Thus, your 300 HP engine uses less HP when there is less LOAD for it to drive.

As you load your truck full of parts and tools, you add weight which can be related to LOAD on your motor or engine. Depending on the amount of weight in the truck, you will use more of the total HP available from your motor to maintain the same speed. When you get to the maximum load capacity of the vehicle, you will be using approximately 100% of the rated HP to maintain the example speed of 55 MPH.

We can use this analogy to understand the Evergreen OM motor stock # 6303R with constant speed programming. The maximum capability of this motor at 1075 or 825 RPM is 1/3 HP. We will use 1075 RPM for the rest of this example.

If, for example, we remove the fan blade from a 1/3 HP PSC motor rated 1075 RPM and install it on this motor, it will operate at approximately 100% of its rated HP or torque to drive the fan blade at the same RPM.

If, for example, we remove the fan blade from a 1/4 HP PSC motor rated 1075 RPM and install it on this motor, it will operate at approximately 75% of its rated HP or torque to drive the fan blade at the same RPM. Why? Because this is a smaller blade that moves less air. Less air equates to less LOAD on the motor.

If, for example, we remove the fan blade from a 1/6 HP PSC motor rated 1075 RPM and install it on this motor, it will operate at approximately 50% of its rated HP or torque to drive the fan blade at the same RPM.

Simply stated, the smaller the fan blade, the less HP or torque the motor uses to achieve the selected RPM due to the technology called “constant speed”. The ECM motor essentially controls the torque the same way you control the gas pedal to achieve a given speed.

Find out more about Evergreen OM motors at ECMMadeEasy.com.

And that’s a wrap on this segment of Motor Minute technical tips. Remember that we provide motor training and product information in multiple formats including videos, literature, podcasts, articles, of course Motor Minute technical tips and classroom education both online and face to face. All of this industry leading training is available at no charge to HVAC professionals at regalmmu.com. Thank you for taking the time to build your motor knowledge.