Questions tagged [harmonics]

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

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35 views

How Power measured by Meters is affected by Harmonics?

I want to know how energy meters (Electro-static or electronic) measure Energy (let's assume power, ignore time) when there are harmonics present. I know what are harmonics, how are they generated ...
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24 views

Active Filter R-L as Frequency Multiplier, no Fc , for overtones of the fundamental

Chebyshev filters have overshoot, which I assume contains harmonics of the R-L or R-C network, but not harmonics of the incoming signal. My goal is to use a differentiator and summer to increase slew ...
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1answer
74 views

Why is total harmonic distortion defined in the following manner?

So the total harmonic distortion is defined as $$THD = \sqrt{\frac{V_{2}^2 + V_{3}^2 + V_{4}^2...+V_{n}^2}{V_{1}^2}}$$ which means Total harmonic distortion is defined as the square root of the ...
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36 views

Where should power factor correction and active harmonic filter connected?

After mains electricity meter, there is an isolation transformer (delta to star) and all load is connected to the secondary of the isolation transformer. We plan to install a power factor correction ...
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19 views

How do I calculate individual output power from overall power from a wind farm through harmonic analysis?

Lets take my problem from the beginning: I take some measurements from a specific wind farm 10.8MW of local area in my country with a power quality analyzer for a certain time, with 256 samples N, 0....
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77 views

Total Harmonics Distortion and DFT

I am trying to understand a design that would enable us to measure/determine the Total Harmonic Distortion. Few key points: The system is micrconcontroller (TI, C2000, dual-CPU) driven electronics ...
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23 views

RFI filter modeling in LTspice w/ triac

I have a few questions about modeling an RFI filter in LTspice with a triac-based dimmer circuit. I'm referencing the circuit described in Figure 11 in Triac Principles and Circuits -- Part 2 (Nuts &...
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3answers
68 views

approximation of a digital signal using the harmonic

I'm new to EE, still struggling in understanding some basic concepts. I'm reading a book which says about approximation: To make the shape of the analog signal look more like that of a digital signal,...
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28 views

How is voltage induced in Yd transformer without neutral connection sinusoidal?

Thia is regarding bank of 3 single-phase transformers having star connected primary with isolated neutral and delta connected secondary. I know that for bank of 3 single phase transformer core flux ...
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1answer
40 views

Calculation of active power using two waveforms with harmonics

I came up with the following example on a textbook I was given. Let's suppose we have an R-L load. I want to calculate the active power P when the voltage and the current applied on the load are ...
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1answer
197 views

RMS value of fundamental harmonic vs RMS of third harmonic

If we have a periodic signal (square wave) with amplitude of 100V. Then what would the RMS value of the fundamental harmonic be compared to the RMS value of the third harmonic? After some suggestion ...
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69 views

Finding a Fourier series of a Burst Fired sine wave having consecutive 2 cycles on & 2 cycles off?

I have been trying to find the solution of the following problem but with no luck. I have a system that generates a waveform of sinusoidal type with the only difference being that this wave has 2 ...
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1answer
34 views

Harmonics modelling in electrical machines

I am currently working with a permanent magnet synchronous machine and I am trying to model the harmonics caused by magnetic saturation, dead time, and non linearities of the frequency inverter. It ...
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1answer
47 views

Spectral lines vs Envelope of PWM wave

On the wiki page of 'Duty Cycle' there is a nice animation that shows the frequency spectrum of PWM wave as its duty cycle is modulated from 0 to 100%. The animation shows the 'spectral lines' as ...
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22 views

Interpretation of IEC 61000-3-6 (Assessment of emission limits for the connection of distorting installations to MV, HV and EHV power systems)

Based on the installation I want to calculate the acceptable current harmonics related to my installation. IEC 61000-3-6 says: For each customer only a fraction of the global emission limits GhMV+...
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2answers
257 views

How to Size Line Reactors and Understanding Reactor Specifications

I've got a 600 VAC, 75 HP VFD that I want to place line and load reactors in series with. Usually, I find charts like this that give me a horsepower table to follow as they are the easiest to use. ...
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4k views

Why is only the fundamental frequency component said to give useful power?

In most books it's said that the harmonic content in an AC line does not transfer power (just the fundamental frequency does), but no explanation. It seems intuitive, but why is that true? Edit: In ...
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1answer
123 views

Why only odd harmonics after signal is amplified? *Plots inside*

Why do I get only odd harmonics appearing? This not only happens at saturation of the transfer curve, but also in the linear portion of the curve. I make an input signal and the power of this will ...
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3answers
138 views

Harmonic detection using lock-in amplifier

Can a third harmonic of a signal be detected using a lock-in amplifier under the same parameters fixed for collecting the fundamental or the parameters needs to be adjusted.Here by parameters I mean ...
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2answers
179 views

Calculating Total Harmonic Distortion using only the first harmonic

I have an assignment for a class where I have to calculate the thd of a signal using MATLAB. I think I have a pretty good understanding of how this should be done, however, my professor instructed ...
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2answers
82 views

Harmonics in power system [closed]

I have seen in some text books that power converters produce harmonics in power systems. How do power converters inject harmonics in a power system?
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50 views

SMPS: Current Mode Control [Sub-Harmonic oscillation] - How to determine ramp when capacitor is unknown?

Currently I am working to charge an DC-link capacitor to prevend inrush currents. I want to charge the capacitor from 0 to 700V using with an Vin of 700V. I want to do this by using an SMPS and found ...
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41 views

Sideband Production

I am trying to understand exactly how sidebands are made. I've seen the math, but I'm looking for more of a component-level understanding of how they are made and what properties of the mixer ...
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110 views

What factors cause the harmonic distortion in ADC at high signal amplitudes?

I have been studying about the ADC's SNR vs amplitude relation. A sample curve is shown below: I am interested in the region rounded (orange) of the gray curve. At that region, we expect to see ...
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1answer
15 views

how to avoid harmonic on intrrupt for proximity sensor in NodeMcu

i have 5v IR proximity sensor for measuring pulse output attached in NodeMCu using intrrupt pin but it gets a random counter on the harmonic environment. it is working fine in Normal situation what ...
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3answers
112 views

Tektronix function generator THD

I am confused by the datasheet of the AFG3021C: https://www.tek.com/link-click-count?nid=75006&url=https%3A//download.tek.com/datasheet/AFG3000C-Arbitrary-Function-Generator-Datasheet-75W282817....
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1answer
110 views

Generating a realistic sine wave in MATLAB

I'm working on a simulation on MATLAB and I need a realistic sine wave which has harmonics. So I know there would be harmonics at 2f,3f... but I am not sure how to determine their amplitude. I tried ...
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1answer
308 views

Harmonic resonance calculation in power-factor correction

Eaton's Power factor correction: a guide for the plant engineer states, Capacitors and transformers can create dangerous resonance conditions when capacitor banks are installed at the service ...
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1answer
51 views

If I use a CAT 2 10x probe does my DSO need to be CAT 2?

I need to measure the harmonic distortion on a solar inverter (power output). I need to buy all the equipment from scratch and was wondering if my DSO needs to be CAT 2 rated if I use a CAT2 10x probe....
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2answers
93 views

Filter harmonics in AC power line [closed]

I run a Toshiba Digital copier machine in my shop and the machine started showing error codes related to power issues a few days ago. This happens randomly during daytime. There were no problems at ...
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1answer
75 views

Harmonic mixing in spectrum analyzers

I'm having a pretty difficult time understanding how tuning works when using harmonics in spectrum analyzers. I'm reading about the topic from Keysight's AN 150. Question 1 The following plot is ...
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2answers
475 views

Why is this the maximum dynamic range in a spectrum analyzer?

In Keysight's popular AN 150 there is a plot of noise and harmonics amplitudes versus the level of the input signal at the mixer (page 57). It's stated there that the maximum n-th dynamic range is ...
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1answer
276 views

How do I calculate THD in proteus?

I know how to plot the Fourier transform, but is there a more precise way to measure the total harmonic distortion? I have this graph: As you see, there's only one distinguishable component at 1 kHz ...
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1answer
689 views

Symmetric vs Asymmetric PWM

I am working on Control of Power Converters, I was reading TI's piccolo DSP ePWM guide and came across symmetric vs asymmetric PWM, I have a good basic understanding about converters, DSP and all. ...
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2answers
453 views

Are ripples and harmonics the same thing?

I started working on the "Direct Power Control of Grid Connected Voltage Source Converters", everywhere in the literature, authors state that one of the major drawbacks of this control technique is ...
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2answers
79 views

Switching mode power supply for Power Line Communication

For a Powerline Communication device that uses the frequency band 42 to 89 kHz. I need to choose a power supply that will not add noise in the powerline and kill my communication band. There are two ...
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2answers
815 views

Why is neutral required in three phase charging of Electric vehicles?

Talking about both three-phase AC as well as DC fast charging (wherein 3 phase AC is converted to DC) in EVs, I think that the 3-phase rectifier represents a balanced 'load'. Therefore I want to know ...
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1answer
292 views

Total harmonic distortion (THD) of a circuit

Where \$V_{sin}\$ is sinusoidal with frequency \$f_{1} = 1 kHz\$. The THD is defined as the sum of the power of all harmonics (except the fundamental) divided by the power of the fundamental harmonic....
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1k views

Power factor and Harmonics associated with Electric Vehicle charging

What is the power factor associated with (typical) DC fast chargers and onboard chargers in electrical vehicles? Also, how much is the harmonic content (especially triple-N harmonics) associated with ...
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1answer
101 views

For induction motors, would one expect harmonics to be different between Delta and Y stator windings?

Given two induction motors with the only difference being that one is wound delta, the other Y, would I expect to see a different behavior if the source is a three phase voltage with harmonics?
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1answer
851 views

How to design filter for inverter for following cases?

I am going to make two pure sine inverters for collage project. Both inverter uses 24V battery as DC voltage source. Switched to ~360Vdc and ~180Vd by boost converter accordingly. Both then switched ...
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3answers
74 views

meaning of having harmonic on special signal

my question maybe seems very simple but, I'm not familiar with the answer of that; what is the meaning of harmonic of the signal exactly? I know the harmonics of the signal are signals whoes ...
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4answers
295 views

what causes voltage harmonics

People keep telling me that Nonlinear loads causes current harmonics and when i ask them about what causes voltage harmonics, they tell me wherever there is current harmonics there is voltage ...
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1answer
432 views

LVDS clock signal EMI

I am working on a project in which we have an an i.MX53 to driving an LCD through the LVDS connector and we fail the required EMC criteria. There are multiple peaks at 40 MHz intervals (starting at ...
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36 views

Very low network impedance close to 13th harmonic frequency

I carried out a frequency scan of an electrical network model with a proposed 220kV transmission line. Addition of this line lowered the system impedance to very low value (to 3 Ohms) at 13th harmonic ...
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57 views

irritation in LTspice

I have written some measurement commands in LTSpice to calculate the weighted harmonic distortion (PWHD) .meas a1n INTEG (I(Lgra)*cos(2*n*180*fg*time)) .meas an PARAM a1n*2*fg .... (if somebody ...
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2answers
920 views

Export error log values from LTspice

I have used .meas expressions to calculate harmonic values in LTSpice. The problem is that these are now in the error log and I cannot export them. Is there a way to export error log values in a .csv ...
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1answer
125 views

Is my laptop charger is working as harmonic filter and absorbing harmonics?

I have a square wave backup inverter (UPS). Whenever the power goes out, UPS turns on but all the fans run with noise and humming sound. I know it is because of square wave and harmonics. But when I ...
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501 views

Why is the chording angle 30 degrees, in a practical alternator?

So far what i have understood... Chording angle in Synchronous Generator/ Alternator is introduced to tackle the problem of harmonics that couldn't be taken care of during the design either in - ...
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1answer
301 views

How to control switching of mosfet in PFC boost rectifier using PI controller?

My aim is to reduce THD in the supply current and I wanna use a simple PI controller for that, to make the inductor current more sinusoidal and at the same time keep the output voltage of the ...