Active Harmonic Filters - Noise-Canceling Headphones for Your Power System

By Jeff Noxon on 8th Aug 2020

AHFs are in

Active harmonic filters (AHFs) have gained a lot of traction in the last couple of years. In the past, high costs meant that active harmonic mitigation methods were reserved for extremely large/complex applications with equally large budgets.

Not anymore. As is typically the case with technology, prices have come down over time, so that active filtration system you've been dreaming of may not be as far out of reach as you think.

AHFs may seem complicated, but they are actually quite simple if you think of them like noise-canceling headphones. Picture the following with me…

Your Last Flight

After buckling your lap belt, you smile a little as you think about how much better this flight will be than your last one.

On your last flight, you were already anxious after arriving a bit later than planned, so the logjam of people waiting to get through security was the last thing you wanted to see. You thanked your lucky stars you didn't get selected for screening and speed-walked to your gate, breathing a sigh of relief every time you heard someone else's name called over the PA.

You cut it close, but you made it. After squeezing your carry-on into the only space you could find, you sank into your seat, glad your ordeal was over. Now all that was left was finding a position comfortable enough to get some much-needed shuteye. Little did you know that your stress was only just beginning.

The cabin noise you could deal with, but four chatty teens loudly debating their senior trip itinerary made even a power nap a long shot. Add not one, but two crying babies, and all hopes for sleep were lost. You soldiered through the flight, but it was rough, to put it lightly.

Not this time. Sure, this time there will still be crying babies and people who don't understand the concept of an inside voice, but it doesn't matter. You're a fast learner, so you slip your new noise-canceling headphones over your ears and... quiet. Blissful quiet.

Noise-Canceling Headphones

Noise-canceling headphones contain a few components that essentially listen to incoming sound waves and instantaneously create a sound wave that is 180 degrees out of phase with them, canceling out the incoming noise. This phenomenon is known as destructive interference and the result is impressive: you hear much more of the noise you want to hear and much less of the noise you don't.

Active Harmonic Filters

There's a lot that goes into active harmonic filters, but a simple analogy is that they work a lot like noise-canceling headphones to clean up your power.

AHFs contain a fast response digital signal processor (DSP) that uses Fast Fourier Transform (FFT) analysis to calculate the harmonics on the system. It then instantaneously creates a sound wave that is 180 degrees out of phase with the harmonics, thus effectively cancelling them out and preventing them from going upstream into the power distribution system.

Active harmonic filters are an extremely effective means of harmonic mitigation, providing the best overall performance across all load ranges. AHFs are capable of canceling multiple harmonic frequencies simultaneously and they're scalable. This often makes them an excellent, cost-effective means of addressing harmonics system-wide, especially when correcting harmonics on an already existing installation. AHFs might also be cost effective when correcting harmonics on a large number of small hp drives, such as in an MCC, or when space constraints dictate an external solution.

Now What?

If you want the best in power quality for your plant, or if you're looking for a solution you can put in place and not have to worry about, active harmonic filters just may be your best bet.

If you're ready to get the ball rolling with an AHF, or if you have questions about which harmonic mitigation method is best for you and your application, call us at (800) 800-2261 and we'll be happy to walk you through your options.