Questions related to frequencies that are generated by mixing other fundamental frequencies.
Questions tagged [harmonics]
174 questions
25
votes
4 answers
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 higher frequency oscillation indefinitely as long as…
crossroad
- 1,390
- 7
- 19
20
votes
5 answers
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 the context of electrical power, so I'm imagining…
k_orolev
- 261
- 2
- 8
17
votes
9 answers
Why harmonic distortion and not at other frequencies?
Despite searching I can't seem to find the answer to this. In understanding harmonic distortion, one piece of the puzzle that is missing for me is:
- why does the distortion manifest at harmonic frequencies and not other frequencies.
Feel free to…
jyoung999
- 183
- 1
- 7
8
votes
3 answers
Capacitor exploding in a paper plant
Two years ago I was in an internship in a paper plant in the Superintendence of Electrocontrol, in the area of maintenance of electrical equipment. Well, they had a problem regarding some capacitor banks that were installed to mantain the power…
dpalma
- 183
- 5
6
votes
4 answers
Is it possible to phase shift a single harmonic rank without shifting the rest of the distored signal?
Let's suppose I have a voltage of 60 Hz, containing distortion due to 3rd, 5th and 7th harmonics (180Hz, 300Hz and 420Hz).
Is it possible to phase shift the 3rd harmonic (for example) without shifting the rest of the signal ? If yes, how and using…
KADEM Mohammed
- 125
- 12
6
votes
1 answer
Help me understand FFT and harmonic distortions
I'm new to FFT and harmonic distortions. I'm dealing with a power system where the phase currents are distorted.
Now I don't understand the concept of FFT and why the harmonics seen in FFT relate to the current waveforms. FFT shows how the current…
rojas777
- 103
- 1
- 7
5
votes
3 answers
Harmonics are bad... But how bad?
In power systems, there are rules and regulations stating what levels of harmonic distortion is acceptable. One example I've seen for voltage distortion is: THD < 8%, single component harmonic <5%. These values are (hopefully) not random…
Stewie Griffin
- 1,547
- 3
- 19
- 36
5
votes
1 answer
Underground cables and resonances in range of frequencies
Is that true that underground cables with no power factor correction have resonances
in range of frequencies which leads to multiple zero crossing distorted waveform?
But why? Is that is because it work as a band-pass filter?
From the book…
Standard Sandun
- 1,695
- 2
- 23
- 38
5
votes
2 answers
50/60Hz Noise Harmonics
I want to wirelessly communicate over low frequencies (<1kHz), and I noticed during some tests that 60Hz noise is showing up a bit at 180Hz (3rd harmonic), and also slightly at 300Hz (5th harmonic): (Ignore the stronger signal I was…
abc
- 619
- 6
- 21
4
votes
2 answers
When a signal has an interharmonic, is the signal periodic or non-periodic?
I have some questions regarding interharmonics. What I'm going to do is first ask just a few, and then as people answer them I would expand this post or create a new question.
Harmonics are sinusoids that have a frequency which is an integer…
alejnavab
- 959
- 7
- 18
4
votes
2 answers
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 given at the intersection of the noise and n-th…
Tendero
- 1,010
- 1
- 12
- 25
4
votes
1 answer
How to use Step Recovery Diodes?
I want to build a frequency multiplier with high multiplication factor. I read some application notes of Hewlett Packard on Step Recovery Diodes. I think a SRD can do what I want. However, I have never used one before. Since they are difficult to…
T. Pluess
- 531
- 3
- 13
4
votes
1 answer
Would low frequency signal (10kHz) have reflection on conducting wires as well?
I am connecting a signal source of 10kHz sine wave with a driver which is a voltage follower made by an OpAmp. The follower has one input and two identical outputs. One output is connected with a device(LOAD) to drive the device(LOAD); the other is…
richieqianle
- 1,612
- 3
- 24
- 44
3
votes
1 answer
What are the main components reducing harmonic distortion?
I'm doing a study of harmonic distortion in a system. The system contain several large VSDs and other non-linear loads. There are no filters in the system, and all cables are relatively short.
Not surprisingly, the results show that the harmonic…
Stewie Griffin
- 1,547
- 3
- 19
- 36
3
votes
2 answers
Understanding source of EMI
I have a device which contains a USB chip which uses 19.2MHz external oscillator.
When I measured the EMI generated from the device, I got series of peaks ranging from 100MHz to 1GHz+.
The peaks have interval of around 3.2MHz. Why do I have…
zud
- 867
- 3
- 9
- 14