Variable Frequency Drives

Variable frequency drives (fan motor VFD) control the capacity of your direct drive industrial fan. Remember, belt drive fans already offer variable speed to increase fan efficiency, so they may not require an external fan VFD.

A system rarely operates at constant conditions, but without external help, the direct drive motor and the fan it runs simply operate at the constant speed of the motor. If system flexibility and energy savings are important to your operations, then you may want to consider adapting your system to allow for variable speeds and improve efficiency.

A fan VFD is a motor controller that adjusts the motor speed to change the fan speed, thus changing airflow. It often serves as an option, compared to the alternative of using a damper. The variable frequency drive is more common, mainly because it can offer better energy savings.

Determining Need for a Fan Motor VFD

Whether you’re making the call on your own or getting ready to contact a fan application engineer, there are a handful of questions that will help you decide if you need a variable frequency drive. Here are some we start with:

  • What is the horsepower of your fan motor?
  • How many hours will the fan be in operation?
  • What is the cost of power in your area?
  • How finite can your system controls be?
  • Are you more interested in reducing up-front cost or higher energy cost savings over time?

Other Helpful Information/Resources

Senior Application Engineer Fred Besasie provides an overview of considerations for Fan VFD and dampers in this 2-minute video, also available to view on our blog: Control Fan fan with Motor VFD or Damper?

When you’re ready to start your project, reach out and connect with one of our application engineers to discuss the details of your fan and VFD specification.