What Is Total Harmonic Distortion In A Generator?

Total Harmonic Distortion In A Generator

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THD, or Total Harmonic Distortion, is a very important subject when it comes to generators, especially now that we are using so many sensitive electronic devices like smartphones, flat screen televisions, computers and smart appliances.

But what is THD, and why is low THD so important?

Let’s look into these questions in more detail, in this simple but comprehensive guide to THD in electric generators.

What Is THD In A Generator?

low total harmonic distortion generator

THD stands for Total Harmonic Distortion, and is a measure of how clean or dirty a power supply is. In a generator, for instance, a clean power flow would have low THD, and the higher the distortion there is the ‘dirtier’ we say the power is.

A generator is just one example, but THD would apply to any type of electricity, and especially to AC or alternating current electricity like you find in your home and use to power all of your lights, appliances, electronics and chargers.

AC in the United States has two main specifications: voltage and frequency. The voltage for most AC power is 120 volts, and the frequency is 60 hertz, meaning that voltage cycles 60 times every second.

THD is most related to that second specification, frequency, because harmonics are a kind of undesirable ‘ghosting’ of that 60 hertz cycle – that is, while this AC electrical current cycles 60 times a second, it will also have pulses or cycles that are twice as fast, four times as fast, eight times as fast and so on, and each of these doublings is a harmonic of the original 60 hertz cycle.

So in addition to the normal, clean 120 volt 60 hertz electrical flow, there will also be power cycles of 120 hertz, 240 hertz, 480 hertz and above. These are distortions of the clean power current, and should be as low as possible, because they can cause real problems with electronics and other appliances and devices. Luckily, in normal domestic, commercial and industrial power supplies, like the power supplied by your utility company, they are.

So, simply put, total harmonic distortion is the total amount of these potentially damaging harmonics in an electrical current as compared to the base frequency of 60 hertz, and is measured as a percentage – with many generators this THD can be up to 20 percent or even higher, from normal residential electricity, like from wall sockets, it should be 3 percent or less, and with the right electric generator it can be even lower.

Why Is THD In A Generator Important?

low thd generator

But what happens if THD is too high? What if there are a large amount of harmonics present in an electrical current?

For our concerns here, the main thing that can happen with too much THD, or too high of THD, is that a wide range of modern consumer electronics products and devices can be damaged or not work properly.

This can include laptop or desktop computers, tablets, phones, flat screen TVs, game systems, smart appliances and even normal appliances with any kind of electronics in their design.

Higher levels of THD can heat up the electronic circuitry in any of those devices, causing circuits to burn out and be permanently damaged, or to shut down and cause (hopefully temporary) service interruptions. THD can also generate radio interference, which can cause any type of wireless device to not operate correctly.

We might want to note that THD is technically different from power surges, which can also cause all kinds of problems and damage to your electronics – but in either case, at least with power generators, the solution is the same, and if you get a generator with low THD you will also get power with much more stable power flow, with less variance and spiking.

What Generators Have Low THD?

The previous sections may seem a bit complex, and believe me, they could have been much more complex, as there is a lot of science and math behind even the simplest of concepts we’re discussing here.

But this part is simple. If you want a power generator with low THD, one that is much safer for all of your electronics, you should get one with an inverter.

In fact, to make it even simpler for you, the products you are looking for will all be called inverter generators, and if you see a product listing with just ‘generator’ and not ‘inverter generator’ in the description, it’s probably not what you want.

What Is An Inverter Generator?

portable generators with low thd

Most old-school generators have a gasoline powered engine which generates electricity, and that electricity is fed directly to the generator’s outlets. This unregulated electricity can be very high in THD, and can also have significant variance in voltage and frequent power surges.

A modern inverter generator, though, has an additional stage built in, which inverts the AC power generated by the engine to DC (direct current) power, and then inverts that back to a very clean and controlled AC current, with much, much lower THD and very stable voltage that is effectively free from surges.

And without any significant levels of THD or power spikes, you can use an inverter generator with all of your electronics without worry!

Who Makes The Best Inverter Generators?

This article is meant to be informational, and not a buyer’s guide to the best inverter generators, but we here at The Final Kit have worked with a lot of generators, for home use, for portable use and worksites, for camping and a lot more, and so it might be helpful if I close by offering a couple of our recommendations for great inverter generators.

In fact, I will list here my top choices for the best generator with low THD at three price levels – budget, mid-priced and premium. I’m not going to get into any descriptions here, but you can be assured that all three of these inverter generators are well made and dependable, are easy to use and work great, and offer very clean and safe power.

Best Inverter Generator With Low THD – Budget

WEN 56380i Super Quiet 3800-Watt RV-Ready Portable Inverter Generator

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Best Inverter Generator With Low THD – Mid-Priced

Westinghouse 3700 Watt Super Quiet Portable Inverter Generator

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Best Inverter Generator With Low THD – Premium

Honda EU3200i 3200 Watt Super-Quiet Inverter Generator with CO-Minder

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