How to Choose the Right Motor for Your Industrial Fan

There are many aspects to consider when choosing an industrial motor, such as application, operation, mechanical and environmental issues. In general, you can choose between AC motors, DC motors, or servo/stepper motors. Knowing which one to use depends on the industrial application and if there are any special needs.

Industrial motors require constant or variable torque and horsepower, depending on the type of load the motor drives. The size of the load, required speed and acceleration/deceleration - especially if it is fast and/or frequent - will define the torque and horsepower required. The requirements for controlling motor speed and position also need to be considered.

There are four types of industrial automation motor loads:

1. Variable horsepower and constant torque

2. Variable torque and constant horsepower

3. Variable horsepower variable torque

4. Position control or torque control.

Variable horsepower and constant torque applications include conveyors, cranes and gear pumps. In these applications, the torque is constant because the load does not change. The required horsepower can vary depending on the application, making constant speed AC and DC motors a good choice.

An example of a variable torque and constant horsepower application is machine rewinding paper. Material velocity remains constant, which means horsepower doesn't change. However, the load does change as the roll diameter increases. In small systems, this is a good application for a DC motor or servo motor. Regenerative power is also an issue and should be considered when sizing an industrial motor or choosing an energy control method. AC motors with encoders, closed-loop control, and full-quadrant drives can be beneficial for larger systems.

Fans, centrifugal pumps and agitators require variable horsepower and torque. As the speed of an industrial motor increases, so does the load output with the required horsepower and torque. These types of loads are a staple of motor efficiency discussions, starting with inverter duty-cycle AC motors using variable speed drives (VSDs).

Applications such as linear actuators require accurate movement to multiple positions, require tight position or torque control, and often require feedback to verify correct motor position. Servo or stepper motors are the best choice for these applications, but DC motors with feedback or inverter AC motors with encoders are often used for tight torque control in steel or paper lines and similar applications.

Different industrial motor types

While there are two main motor classifications - AC and DC - there are more than three dozen types of motors used in industrial applications.

While there are many motor types, there is a lot of overlap in industrial applications and the market pushes to simplify motor selection. This narrows the practical choice of motors in most applications. The six most common motor types suitable for the vast majority of applications are brushless and brushed DC motors, AC squirrel cage and wound rotor motors, and servo and stepper motors. These motor types are suitable for the vast majority of applications, while others are used only for special applications.

Three main types of industrial motor applications

The three main applications for industrial motors are constant speed, variable speed, and position (or torque) control. Different industrial automation situations require different applications and problems and their own problem sets.

For example, if the top speed is lower than the base speed of the motor, a gearbox may be required. This also allows smaller engines to run at more efficient speeds. While there is a wealth of information on the web on how to measure engine size, there are many factors that users must consider as there are many details to consider. Calculating load inertia, torque and rotational speed requires the user to know the total mass and size (radius) of the load, as well as parameters such as friction, gearbox losses and machine cycles. Load changes, acceleration or deceleration rates, and the duty cycle of the application must also be considered, otherwise the industrial motor may overheat.

After selecting and determining the motor type, users also need to consider environmental factors and motor housing types, such as open frame and stainless steel housings for washdown applications.

By focusing on these key criteria, you will be able to quickly narrow your search and speed up the process of selecting a motor for your application. Even with this knowledge, choosing the right product mix for your application can be complicated. If you are not sure what product you need, please consult our experts for details, please contact us at amamda@tingertech.com.