Looking for a VFD for your next project? Or just need to know what they are? Read the article below.

What is a VFD?

A VFD is a variable frequency drive. The name implies what the unit is doing for the most part. It is taking the power input and varying the frequency and  the voltage of the electricity coming in to slow down and speed up the motor.  

What are VFD's Typically Used For?

VFD's have a few different uses in the HVAC world. You have probably seen them on rooftop units. These were used to meet blower compliance for ashrae on rooftop units. They are typically giving two speeds for the unit to run at plus a soft start up. We see them used on hydronic pumping as well to help fix flow issues. Sometimes they are there to only simply start a large fan motor. The soft start feature lessens the amp draw and allows quiet start ups instead of banging on. We also use them in large AHU's that are constant variable volume. A controller can give a VFD a 0-10v or 4-20ma signal to ramp the motor up and down. The controller is then able to control unit to static pressure. 

VFD Options: 

If you are looking for a VFD then go ahead and fill out a ticket with the tab on the left side of your screen. We will need to know the following for getting a selection.

1. Voltage
2. Amperage
3. Phase
4. Horsepower
5. Enclosure type required. (mostly on the bigger sizes)

We can typically get the following brands of VFDs

• Johnson Controls
• Honeywell
• Yaskowa