question in Ballast (5)
Hi, guys, I have some questions about below paragraphs. What's the meaning of "nonlinear"? How can adding an out-of-phase voltage cancel the harmonics? I hope some one can kindly answer my questions. Many thanks in advance.
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Hello,
I think this article talks about the alternate current wave interference phenomenon: waves with the same frequencies amplify each other. Waves of 60hz, 120hz and 180 hz will have their crests, maximum and minimum points, coincide and reinforce each other. This leads to making the wave too powerful and overheating as mentioned in the text.
I hope I got it right
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Yes, I tried to answer your questions Yanron. Let me explain it in a more detailed way.
What's the meaning of "nonlinear"?
There are two types of electricity: direct and alternating current (ac &dc). Direct current runs continually in a single direction, its graph is a linear function. Alternating current is the most used type of electricity, because it can be converted to different voltages easier than direct current. Its graph looks like a sine function that looks wavy, which is nonlinear.
How can adding an out-of-phase voltage cancel the harmonics?
In my previous comment, I mentioned wave interference aka 'harmonics' which you can learn about from a basic Google search.
As I said, AC current looks like a wavy line that repeats itself. Phase is a length of a cycle. Frequency is a number of phases in a second. Appliances that have synchronized AC frequencies, wear out faster because their waves overlap and interfere with each other causing overheating. To prevent this from happening, out of phase voltage is introduced.
If you want to visualize it, imagine a bunch of kids jumping on a trampoline. If they all jump sporadically, the trampoline will not bounce them back that much. If they coordinate and jump simultaneously, the trampoline will make them jump higher and higher every time and the trampolines surface will get torn apart sooner. -
please watch this video. They talk about harmonics, linear & non-linear load, oversizing neutral conductor, passive (harmonic) filters & more. please scroll down down & you see the video.
https://electrical-engineering-portal.com/recognize-harmonics-symptoms (web site)
https://www.youtube.com/watch?v=JFCG53yoCxI&feature=emb_logo (direct link to video)
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The video show ways to cancel (they call filter) the harmonic (current/voltage) problem (they call distortion) including adding an equal but out-of-phase voltage. also see this video fundamental of harmonics - hope this will help you to understand the process of adding an equal but out of phase voltage!
https://www.youtube.com/watch?v=hPrGYK5YUEE
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