Proper installation is essential to the success of efficient variable frequency drive (VFD) implementation. Here are four crucial components to consider so that you can get the most out of your investment.

VFD Installation Tip 1

Make sure all the electrical connections are properly secured. Motor starters can be indifferent to how they are wired. If not wired right, the VFD will fault because it is monitoring things that a motor starter cannot detect. The VFD fault seems like a headache so don’t pull it out, but rather check the wiring. Keep the VFD, then get it wired correctly and maximize your investment.

VFD Installation Tip 2

VFDs on blowers will only work well if the mechanical installation is as good as the electrical installation. Improper impeller pitch, housing, and rotation configuration will make the motors run at the VFD's maximum current rating — which is a lot higher than the motor's maximum current at full load. The motor will then overheat and the VFD will fault. The solution is not to reset the fault or pull out the VFD, but to troubleshoot all of the installation so your equipment investment lasts a long time.

VFD Installation Tip 3

Stick to the manufacturer’s installation and engineering specs for cable length; each VFD manufacturer is different. When the length exceeds specific specifications, additional filtering installation will be required on the VFD load side so that harmonics (a fancy word for electrical noise) will be cleaned up. Bad harmonics result in poor VFD performance and could ultimately damage your motors.

VFD Installation Tip 4

You cannot afford to run your system without cooling it. The amount of heat produced from a single 15hp 480v VFD is approximately the same amount of heat as a 1,200 watt light bulb. That’s 20 times as hot as a household light bulb. Consider that the average setup has six to 12 VFDs (one for each blower) that are enclosed in an airtight steel box with no cooling system. This will result in the VFD faulting and going into an overheat condition effectively shutting your equipment down until the system cools. Downtime and loss of revenue will be reduced with a smart system to cool your VFDs.


Troy Huisman is president and founder of Superior Control Systems. His company are experts in carwash control systems installed nationwide. They can be reached at or 480-966-1400.