Understanding motor applications to help design more efficient motors - part 2 of 2

October 2019

In last month’s blog post titled “Understanding motor applications to help design more efficient motors - part 1 of 2,” we dove into the intricacies surrounding specific motor applications to learn how that can help design an ideal motor for a given system from an electrical design standpoint. In this part, we discussed the main mechanical considerations you should keep in mind, as well as a few other issues, with Nidec Motor Corporation’s Application Engineering Manager, Patrick Hogg.

One of the first important mechanical factors to consider is what type of enclosure the application will require. Hogg says that he runs through a list of questions in his mind. “What type of protection does it need? Is it going to be inside of a building, or is it going to be on the coast somewhere? What kind of things are going to be moving from the outside air into the motor? Do I need to protect it so that none of the outside air gets in there? What if it’s in a hazardous location? Is there going to be an explosive gas or a dust in contact with the motor? Is it not in direct contact with but located inside a room that’s in contact with that kind of substance?”

How is the motor installed?

It’s also important to consider how the motor will be installed. According to Hogg: “We have horizontal motors with feet on them that you can install on a wall. If it’s installed on a wall and it’s shaft-down, it might have areas where water can enter from the top if something is dripping down from the ceiling or an overhead pipe begins to leak. In cases like that, we can put drip covers on them.” Looking at these types of installation and enclosure considerations can help design effective methods to protect the motor.

Another critical component is the type of connection that will fit the specific application. This typically ties into the torque requirements for the motor. Hogg explains, “If I’m connecting to a belt or a gear, the belt or the gear ratio could be helping me out with the torque; but if I connect it directly I need to make sure that the motor is generating enough torque to start and drive the required load the whole time. There’s actually a big push in the industry to move to direct drive because we have variable speed now.”

According to Hogg, variable speed capabilities allow for full-load torque across all the speed ranges, which can aid in starting of direct driven systems. The tradeoff is that this requires a bigger motor in some cases. Another benefit of direct drive is that this allows for the elimination of the gears, the belting and any other torque increasing devices that may be used; making it possible to connect the motor directly to the driven equipment. Hogg states that, “You have to make sure you size the motor correctly for the torque. You can then control the speed of your equipment so it’s nice and it can often be more cost-effective as a full install, but you have to make sure you size it correctly when you’re going to a direct couple.”

Hogg also stresses the importance of understanding the thrust load requirements. “When it comes to the installation and connection of vertical motors, you have to ensure that the motor allows for the appropriate thrust load, so you need to know the thrust from the pump that is required to make sure that your bearings will last long enough and they can overcome the thrust requirements.”
Truly understanding an application and all angles of what it requires from the motor can help obtain the most value out of driven equipment. Designing a motor to be a value-added part of a system helps achieve greater energy and economic efficiency.

Bio: Patrick Hogg is the Application Engineering Manager for general industry and pumping at Nidec Motor Corporation. He received his bachelor’s degree in Mechanical Engineering from Southern Illinois University and his MBA from the University of Missouri-St. Louis. Mr. Hogg has over 10 years of experience in the motor and pump industry and has been an active HI Member since 2013.

Sources: All info obtained from an interview with Patrick and Episode 21 of the Pumps & Systems Podcast (https://www.pumpsandsystems.com/podcasts).