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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, ...
DSP_CS's user avatar
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4 votes
2 answers
186 views

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 ...
asd's user avatar
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1 vote
2 answers
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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 ...
Mhan's user avatar
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1 answer
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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 ...
Lorenzo Marcantonio's user avatar
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33 views

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 ...
Ultra67's user avatar
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1 answer
76 views

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 ...
NICEGUY NICEGUY's user avatar
2 votes
0 answers
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 ...
Vitaliy Petliakivskyi's user avatar
-2 votes
1 answer
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 ...
Dan Bullard's user avatar
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1 answer
66 views

Mathematical relation between \$I\$-\$V\$-curve nonlinearity and harmonic distortion spectral components

A nonlinear resistor has a bent/distorted \$I\$-\$V\$-curve. We can approximate its \$I\$-\$V\$-curve with a polynomial model such as: $$I(V)=I_0 + \frac{1}{R_1}V + \frac{1}{R_2}V^2 + \frac{1}{R_3}V^3 ...
tobalt's user avatar
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Control a resistance in AC circuit without generating current harmonics

I am currently working on a project aiming to control the amount of current flowing through a resistance from 0 to nominal in a continuous manner. The catch is that the power is 230 VAC 50 Hz. My ...
FuriousHelicopter's user avatar
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What are the highest permissible current harmonics input to the grid?

I'm in the process of completing my Master Thesis and I need to model the current harmonics input of large-scale PV plant into the grid. We're talking about 100MW connected to the 110kV line, using ...
harry's user avatar
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290 views

Mixers and LO Harmonics

Say we have an RF signal with components at \$F_{LO}+\Delta\$ and \$3F_{LO}+\Delta\$ and we want to down-convert so that \$F_{LO}+\Delta\$ becomes \$\Delta\$. We will mix this RF signal with our local ...
Fraser Price's user avatar
2 votes
1 answer
142 views

Capacitor for quartz crystal in harmonics

I saw a FM transmitter radio circuit, which was an easy one and had a 20 MHz quartz crystal, on internet. It promised to fix the frequency at 100 MHz. I soldered the components together and tried at ...
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Power Quality Measurement & Reporting Standards

I'm analyzing power quality in low and medium voltage facilities (50/60Hz; 0.48 - 69 kV; factories, campuses, etc.) while trying to apply existing standards wherever possible. In addition to demand ...
Errorum's user avatar
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88 views

Calculating harmonic currents of a circuit with L and R

I want to calculate harmonic currents of the following circuit in LTSpice. Circuit operates with 100MHz square wave with 1ns rising and 1ns falling edge and 5V: In FFT view, LTSPice shows me that ...
Mubin Icyer's user avatar
1 vote
1 answer
114 views

PFC (Power Factor Correction) harmonics

I recently succeeded in creating a powerful buck PFC with a value almost equal to 1 (0.999) As you know there are always problems when dealing with real life circuits. I mean, the PFC value is real, ...
NBK SOFT's user avatar
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3 votes
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136 views

Why does the current THD increase and voltage THD decrease when increasing the inverter switching frequency?

I have a three phase inverter model and I am investigating the effects of an increased switching frequency for pre-defined LC filter parameters. It is a simple MATLAB Simulink model: DC source, ...
mikebuba's user avatar
0 votes
1 answer
92 views

Is harmonic distortion only a problem for the power company?

I know that harmonic distortion is a problem for the power company because it influences the power factor, but what about me as an end user? In my situation I would use 9 drivers of 200W (230VAC/48VDC)...
Rakward's user avatar
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2 votes
2 answers
705 views

What is the correct relationship between active, reactive and apparent power in non-linear AC systems?

I am somewhat troubled by the 'basic' formula that describes the relationship between apparent power (S), active power (P) and reactive power (Q) in AC systems. This formula is ...
JeromeBu1982's user avatar
2 votes
2 answers
96 views

Harmonic power losses, approach A or B?

Which is the correct approach to determine the total power loss in a wire with a given harmonic spectrum: Approach A: $$ P = \sum_{i=0}^n (i_{n, RMS}^2 \times R_{n})$$ Approach B: $$ P = i_{total, RMS}...
alvrm's user avatar
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1 vote
0 answers
71 views

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 ...
Boatelectrician's user avatar
0 votes
1 answer
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 ...
tobalt's user avatar
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1 vote
2 answers
126 views

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 ...
Dynamic_equilibrium's user avatar
0 votes
3 answers
178 views

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?
Marc Paul Eumague's user avatar
0 votes
1 answer
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 ...
JustCurious's user avatar
0 votes
1 answer
153 views

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 ...
Daniel Oren-Ibarra's user avatar
-2 votes
2 answers
108 views

How to add harmonic distortions to guitar amp? [closed]

I was reading about the carver challenge,(https://www.stereophile.com/content/carver-challenge) and read that he had added a series of potentiometers to one of his amps that had allowed him to ...
Daniel Oren-Ibarra's user avatar
0 votes
1 answer
39 views

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 ...
Mathias Boulé's user avatar
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3 answers
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. ...
Vignesh C's user avatar
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-1 votes
1 answer
1k views

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 ...
Hari 's user avatar
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0 votes
2 answers
221 views

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 ...
Samuele Benito Di Gioia's user avatar
2 votes
2 answers
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 ...
Cartoon Ryan's user avatar
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0 answers
66 views

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, ...
JMy's user avatar
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0 votes
1 answer
397 views

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: ...
Shubham Dhiman's user avatar
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0 answers
66 views

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 ...
Vineeth's user avatar
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0 answers
58 views

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 ...
Danish Umer's user avatar
0 votes
1 answer
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?
OMAR's user avatar
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0 votes
2 answers
388 views

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, ...
Piko's user avatar
  • 67
0 votes
1 answer
151 views

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 ...
Samuele Benito Di Gioia's user avatar
0 votes
0 answers
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 ...
WTFisChris's user avatar
1 vote
0 answers
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 ...
Frank's user avatar
  • 293
0 votes
2 answers
245 views

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 ...
Autodidact's user avatar
0 votes
1 answer
179 views

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 ...
Samuele Benito Di Gioia's user avatar
0 votes
1 answer
82 views

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 ...
Samuele Benito Di Gioia's user avatar
0 votes
1 answer
208 views

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 ...
Irenaius's user avatar
1 vote
2 answers
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
gripen's user avatar
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0 votes
0 answers
183 views

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 ...
Δημήτρης Βενέτης's user avatar
1 vote
1 answer
90 views

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 ...
AndroidV11's user avatar
0 votes
1 answer
143 views

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 ...
8cold8hot's user avatar
  • 175
25 votes
4 answers
2k views

Ceramic resonator changes and maintains frequency when touched

I'm experiencing a weird phenomenon with a ceramic resonator test circuit, where the frequency of its output can be changed by touching the circuit with my finger. The circuit would maintain this ...
crossroad's user avatar
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