Harmonics FAQ video library

Eaton’s Harmonic FAQs video library, hosted by Dan Carnovale, can help individuals from all different levels of education understand what harmonics are and explain many different solutions for mitigating harmonics on an electrical power system.

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General harmonics
Harmonic symptoms
Harmonic sources
Harmonic solutions

Harmonic frequencies

Harmonic sources

Harmonic symptoms

Harmonic solutions

Help with harmonics

Harmonics in power systems result in increased costs and downtime. Get help from Eaton.

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Harmonics analysis studies

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General harmonics FAQs

How do you calculate total harmonic distortion or THD and total demand distortion or TDD?
Learn and understand how to calculate total harmonic distortion (THD) and total demand distortion (TDD).
What are the typical characteristic harmonics for electrical loads?
Learn what typical characteristic harmonic waveforms look like for electrical nonlinear loads.
What is the Ohms Law explanation for harmonics?
Learn where harmonics come from and how harmonic currents flow using a simplified Ohm's Law explanation.
What you need to know about harmonics and generators?
Learn how harmonics interact with generators increasing voltage distortion to ensure loads operate correctly on the generator or utility source.
IEEE 519 Standard, what do I need to know?
Learn and understand the key points of the IEEE 519 Standard for harmonics including THD and TDD limits for voltage and current distortion.
What do you mean by "harmonics are not a problem unless they are a problem"?
Learn why Eaton says," harmonics are not a problem unless they are a problem" especially because harmonics are the new normal on power systems.
What are some harmonics case study examples?
Eaton works regulary with clients on solving the harmonics issues. Here are two specific case studies involving harmonics that we solved.
Where can I get more information to learn about harmonics?
Eaton offers a wide array of information on harmonics including a dedicated website, whitepapers and tools.
How do harmonics relate to power factor and displacement power factor?
Discover the difference between total power factor and displacement power factor.
At what percentage of my transformer loading should I be concerned with harmonics?
Transformers heat up from harmonics find out at what percentage you should derate your transformer based on harmonic load.
What is harmonic resonance and how does it work?
Harmonic resonance, particularly parallel resonance can wreak havoc on a power system. Take a look at what do about it.
Is a temporary measurement as good as a long term trend for harmonics?
With harmonics do I need to do permanent measurements or can I use temporary measurements. The determining factor is, what are you going to use those measurements for?
How do I calculate total demand distortion (TDD)?
The IEEE 519 standard requires you to calculate the total demand distortion and compare it to the tables. We show you how to do that in this FAQ.
What is the difference between THD and TDD?
The main difference is how THD and TDD are calculated. In particular, it is simply the value that is in the equation used to calculate TDD and THD.
How much power do I lose because of harmonics? Do I pay for harmonics on my power bill?
We start by reviewing the different components of power and the power triangle including real power (watts or kW), reactive power (kVARS) and apparent power (kVA) to answer the question, do harmonics impact my bill.
Why is voltage distortion bad? Are multiple zero crossings on voltage from harmonics a bad thing?
Voltage distortion, which can be caused by multiple zero crossings resulting from harmonics, can lead to mis-operation of electrical equipment.
Do you connect a harmonic filter to the ground?
Do you connect a harmonic filter to ground? No. And in this video learn more about the nature of harmonic currents and why the design and application of harmonic filters require a different approach with a three-phase system.

Harmonic solutions FAQs

How does harmonic phase shifting work including a detailed mathematical explanation to reduce system harmonics?
See mathematical explanation of phase shifting cancellation for harmonics using transformers and 6-pulse drives to achieve a 12-pulse system.
Can I increase my linear load to cancel my harmonics?
See how 60 Hz current or linear load and harmonic current or nonlinear load interact.
How can I correct harmonics with K-rated harmonic mitigating HMT or drive isolation transformers?
Learn how to correct harmonics with transformers — K-rated, harmonic mitigating (HMT) or drive isolation transformers.
How can I eliminate or cancel harmonics with phase shifting transformers?
Learn how to eliminate or cancel harmonics at a system level with phase shifting or harmonic mitigating transformers.
How does a drive dedicated or broadband filter work?
Learn about drive dedicated or broadband filters and how they work to reduce harmonic current distortion on an individual VFD.
How does a passive harmonic filter work?
Learn what a passive harmonic filter is and how it works to correct power factor and minimize harmonics current distortion.
How does an active harmonic filter or harmonic correction unit HCU work?
Learn how active harmonic filters (AHF) or harmonic correction units (HCU) work to reduce current and voltage distortion.
How does an 18 pulse drive work?
Learn how 18-pulse drives work and how they minimize harmonic currents, voltage distortion and THD.
How does a 24 pulse medium voltage drive work?
Learn how 24-pulse medium-voltage drives work and how they minimize harmonic currents, voltage distortion and THD.
What is a line reactor or DC choke and how does it work?
Minimize harmonic load distortion of variable frequency drive (VFD) applications cost-effective AC line reactors, inductors, DC chokes reduce THD.
What is the difference between a tuned and de-tuned filter?
All filters are typically detuned. If you're talking about harmonic filters, most of you would very rarely ever see anybody tune a filter or make a filter. Learn why.
What does oversizing my electrical equipment do for harmonics (k-rated transformer, generator, etc.)?
It depends on your goal. Harmonics is two part issue: overheating and voltage distortion. We talk about how each factors in to right-sizing your electrical equipment.
How does a harmonic filter work?
Passive filters, active filters, broadband filters and drive-dedicated filters are all available. We will look how each works and their benefits.
Is it more economical to buy low distortion loads or to apply harmonic correction?
Discover if it is more economical to buy low distortion loads or buy a standard load with harmonic correction after the fact.
AC line reactor vs DC choke - which is better?
Whether you select an AC line reactor or DC choke comes down to just a few basic variables. Take a look.
Does a drive isolation transformer do the same thing as a line reactor?
There are specific factors that help determine which is best to use, a drive isolation transformer or a line reactor.
Do I need a harmonic filter for every drive or is it better to install a single filter for all of my drives?
The answer to whether or not you need a single filter or multiple filters really depends on the application. Take a look at when that is necessary.
How does a delta zig-zag transformer eliminate or minimize harmonic currents?
Explore the function of delta zig-zag transformers in eliminating or minimizing harmonic currents.
Does a delta-wye transformer cancel all harmonics?
A delta-wye transformer will not cancel all the harmonics. The delta-wye will recirculate the triplen harmonics back to the load. But if you utilized these transformers in combination with other transformers to create phase shifting, you can do some cancellation.

Harmonic sources FAQs

Does a 5% reactor cause a 5% voltage drop at my drive?
Learn if the voltage into your VFD is reduced significantly by having a 5% or 10% line reactor in front of your drive.
How do I know if my project will have a harmonics issue and how do I determine the right harmonic solution?
Learn and understand if your project will have harmonics issues and which harmonic solution to select.
Should I be more concerned with 100A of 5th harmonic or 80% THD? Can I increase my linear load to cancel my harmonics?
Learn the difference between harmonics measured in Amps versus harmonics measured in THD or percent distortion.
Do harmonic and 60 Hz load currents change at the same rate?
Learn and understand how 60 Hz linear load and harmonic load current change at different rates for loads.
What is a nonlinear load?
Learn and understand the difference between linear and nonlinear harmonic loads.
Why do most UPSs have active front ends but VFDs have diode rectifiers?
Most UPSs today have active front ends, but most drives still have diode front ends. Let's take a look at the difference, which often comes down to economics.
What is the difference between EC motors and motors with VFDs?
EC motors and VFDs perform similarly, but how they handle the situation is different. Learn more.
Do I need to worry about input harmonics, output harmonics or both with a VFD?
We take a look at how both input and output harmonics would effect an electrical system using a VFD,
Do all harmonics come from the loads or do some come from the utility source?
Harmonic currents are generated by the loads, but can we have sources of harmonic that come from the utility side? The answer is yes, in two ways, and you can learn how.

Harmonic symptoms FAQs

How do I know if I have harmonics on my system based on the symptoms?
Learn and understand if you should expect harmonics on your power systems based on your loads and systems of harmonics.
Where do you start with harmonic analysis?
Learn where to start with harmonic analysis, modeling and measurements once you have identified that you have a harmonic issue.
How can you determine you have a harmonic problem by identifying symptoms and sources of harmonics?
Learn how to determine if you have harmonic problems by identifying harmonic symptoms and sources and understand voltage and current harmonics.
What are the typical characteristic harmonics for electrical loads?
Learn what typical characteristic harmonic waveforms look like for electrical nonlinear loads.
What if I had 4000 percent Ithd on my neutral conductor?
A high level of total harmonic voltage or current distortion on an electrical power system can cause many problems and it is important to understand how harmonics are generated so they can be reduced or mitigated.
Who cares or should care about harmonics?
Learn who should care about harmonics, including electrical designers, consultants, contractors, electricians, utility personnel customers, owners and more.
If I see harmonics on my meter, breaker, etc. should I be concerned?
At what level of harmonic current or voltage do I become concerned? We are going to have harmonics on our power systems. Here is when to be concerned.
Why is my harmonic distortion higher at night than during the day?
When people say, why is my harmonic distortion higher at night than during the day, I typically ask if we are talking about the percentage THD or the actual harmonic currents.
Why does it seem like voltage THD is always lower than current THD?
To answer that question, it really comes down to the THD calculation. Let's get into the details.
Why are harmonics intermittent (not always there at certain times, days, etc.)?
Intermittency of harmonics is not so much that the harmonics themselves in terms of the RMS values are changing much. It's usually a percentage that's changing. Let me explain.

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