# Questions tagged [harmonics]

Questions related to frequencies that are generated by mixing other fundamental frequencies.

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### Fan noise due to Harmonics while running on UPS?

When mains is not available, ceiling fan will run on UPS and create a different sound/noise. I know that it is due to harmonics. But how can we remove this noise? By getting a high quality inverter, ...
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### How do I calculate THD?

I want to calculate the total harmonic distortion of the signal using this graph and formula. The formula is taken from this page: Calculating harmonic distortion First Question: So my problem is to ...
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1 vote
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### Filter design according to harmonics in an inverter

According to the Fourier series, when AC waves of different frequencies are added to the fundamental frequency, we can obtain waves such as square and sawtooth. When we filter out the harmonics in ...
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### Is there a way to reduce harmonic current for a single phase VFD without using an active filter?

I have this smallish VFD, for a 2.2kW motor, single phase. So it's smallish as VFD but as a single phase load is quite big; this is Europe so it's 230/50Hz land. However, it need to pass EMC testing ...
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### Industrial product IEC 61000-3-2 compliance

I have a question related to IEC 61000-3-2 standard for current harmonics limits. I am working on an industrial product rated for 500W that connects to the grid (220VAC). The standard states that ...
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### Harmonics of Ethernet (100MBps) MLT-3 signals [closed]

I have EMC Issue (Radiation) as attached..where at some frequencies the emission levels are exceeding the limits.. I use 36V power and Ethernet (MLT3) for communication. These failing frequencies are ...
122 views

### OpAmp Selection | Sine Wave Amplifier: 30 MHz, 30Vpp with 15V offset

I am currently working on amplifying the output sine wave of the TG5011 professional signal generator. Below are the specifications for the amplifier I am aiming to create: Power Supply: A single ...
110 views

### What two laws of harmonics are demonstrated here? [closed]

I clipped the top and bottom of a sine wave at exact reciprocal angles (73.73159173° to 106.2684083° and 253.73159173° to 286.2684083°) to prevent the creation of even (red) harmonics (by being ...
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### Yacht generators with common neutral - Voltage Balance & Harmonics

In a marine application, a yacht using two generators (not connected in parallel), to feed 7 separate circuit panels, separated disconnects but common neutral. Both generators have their neutral ...
143 views

### Reasons for subharmonic mains noise in preamplifier

I have a preamplifier based on an OPA1611 that I wanted to characterize. The amplifier is in a fully enclosed and earthed metal chassis, which has an AC-DC converter in it. The mains cabling goes ...
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1 vote
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### What is this strange harmonic content present in a resonant circuit output waveform?

The following is an LC circuit excited at resonant frequency 15.915Hz (L=10mH, C=10mF.) I would expect the output to have only the resonant frequency (constantly increasing in amplitude) since the AC ...
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### Generate combined sinusoidal waveform (fundamental, 2nd, 3rd...) using PWM

I know that I can make sinusoidal waveform using SPWM, but how can I combine fundamental signal with different frequency signal (2nd, 3rd...) on a single signal created by SPWM?
173 views

### Average power of a non-linear load

I have the following formula to calculate the average power dissipated in a non-linear load: I would like to know what happens if the phase between the voltage and the current (for a specific ...
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### How to enrich harmonics in audio?

I'm designing a guitar pedal to boost harmonics in the signal here: Falstad Link I'm wondering if there are ways to boost harmonics that don't clip the signal, as well as any adjustments I should make ...
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### Harmonic n intensity varies greatly between phase - Is it important?

I tried to find explanation over this - maybe my terminology is wrong, couldn't find anything. I wondered if it's important the for 3rd harmonic, intensity of voltage of Phase A is almost half the one ...
114 views

### Signal Integrity in electronic systems

When I went through EMC testing of some electronic boards, I observed that the frequencies of the EM waves generated by the boards are at the fundamental frequency with multiples of some whole number. ...
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### Fundamental vs true RMS values - Can the fundamental be higher than true RMS

Here is a practical situation: We are measuring harmonics with a Class-A PQ device. At certain times we have the fundamental values of current higher than the true RMS values. I would like to know if ...
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### Are voltage harmonics critical in the electric grid?

I'm a student of Politecnico di Milano and today my prof during the lesson told me that it's important to limit current harmonics into the grid and not voltage harmonics because these last do not ...
211 views

### Fourier transform and what it represents

Suppose we have a sine voltage supplied to a resistive load. When I perform a Fourier transform to this signal in the frequency domain what do I get? All values of g(a) will be 0 except for the ...
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### Is it viable to short pitch different windings by different degrees of short pitching in the same synchronous generator?

In the design of a synchronous generator one can chose to eliminate or reduce harmonics at the expense of emf. The pitch factor $K_p = \cos(\alpha/2)$, which is always less than or equal to 1, ...
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### Reason for frequency steps shown in Simulink FFT analysis tool

While using the FFT in Simulink tool, I have observed that if more number of cycles are selected then frequency steps in which harmonics percentage is shown is also divided accordingly. For example: ...
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### How to use DFT to find harmonic content of an AC waveform?

I am kind of new to this coding and simulation environment. For my first project I need to take samples of current signals from power line and find out the harmonic contents using DFT. I haven't done ...
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### Triplen harmonics not appearing in the output of DigSilent PowerFactory 2021

I am running simulations for harmonics resulting from the connection of an offshore wind farm to the main grid on DigSilent PowerFactory 2021 SP3. I am using a script to run multiple scenarios and ...
167 views

### Harmonics in neutral conductor

If he multiplied the 10 A by 3 this means each phase has 10 A of harmonics. So, shouldn't they cancel out at the neutral just like the rated frequency currents?
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### Inverter Fourier analysis

I have an inverter circuit like below: I will use bipolar control method to produce sine wave. Our teacher said us prove basic harmonic of inverter is equal to multiplying of modulation index and Vd, ...
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### Do energy storage systems really improve the quality of the energy?

I know that an ESS (energy storage system) improve power quality issues avoiding interruptions, controlling the voltage and the frequency, injecting reactive power into the grid thanks to the ...
57 views

### I’m trying to manipulate the harmonics of a square wave, and my circuit is not working

I am trying to build a circuit that can boost or cut multiple harmonics of a square wave. I am trying to use a graphic equalizer gyrator circuit. I have had very little luck with this. Any suggestions ...
1 vote
55 views

### What's wrong with my experiment to observe harmonics caused by receiver saturation and non-linear behavior?

I've been trying to devise an experiment to produce a third order harmonic in radio receiver that's been saturated, but I'm not seeing the expected results. My understanding of the theory is that when ...
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### Adding harmonics to the square wave means

I have generated two imperfect square waves by: Adding fundamental frequency with 10 odd harmonics. Adding fundamental with 20 odd harmonics. What difference should I observe between two imperfect ...
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### Harmonics produced by LCC converters

Considering an LCC HVDC system and that the flow of power is ALWAYS in the direction shown in the figure. I know that converters in general produce harmonics. My questions are: Does this HVDC system ...
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### Reduction of the harmonic currents in LCC HVDC systems

Why there is a reduction of the harmonic currents in the AC side in an LCC HVDC system? Here is represented the AC current in yellow, in red the DC voltage and the sinusoidal waves are the AC ...
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### Transformer Harmonics

A typical installation is Load - 400 V net - Transformer 1:25 - 10 kV net If the load is for example a SPS, the 400 V net can contain harmonic currents and thus have a considerable THDi. How can the ...
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578 views

### Harmonics in transformers

could you explain what it is that causes harmonics in transformers? I've read that these are the reasons, but it still doesn't give me a proper explanation. Saturation of the core Magnetizing current
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### Harmonic Balance works, transient does not work!

I have an oscillator circuit and the harmonic balance simulation shows there is oscillation in Vout: However, when I run a transient analysis, the results are totally different and show there is no ...
1 vote
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### Can AC harmonic quantities be expressed as a sum of phasors of different frequencies without confusion?

https://www.electronics-tutorials.ws/accircuits/harmonics.html The problem with AC harmonics is that each term has a different frequency, being a integer factor of the first frequency. I was wondering ...
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### Why does wound rotor IM have the belt leakage but the squirrel cage rotor does not?

According to the description on page 159 of Prof. Lipo's book "Introduction to the AC Machine design": It is important to mention that the harmonic leakage is important only for wound rotor ...
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