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Difference between ripple and harmonics

  1. May 24, 2010 #1
    what is the difference between ripple and harmonics??


    particularly plz explain harmonics...

    how it actually is harmfull ..

    and what is the reason of its origin???
     
  2. jcsd
  3. May 24, 2010 #2

    MATLABdude

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    Ripple (as it usually applies to the DC output from a power supply) are usually artifacts from the rectification process:
    http://en.wikipedia.org/wiki/Ripple_(electrical)

    Harmonics don't just apply to ripple: anytime you're drawing large amounts of power or have large non-linear loads attached to your mains power, you're deforming the sinusoidal waveform that's coming in. If you've studied Fourier series, you know that anything that isn't a perfect sinusoid will have higher frequency components. Since the ripple isn't perfectly sinusoidal, it'll have higher frequency components, often at a significant amplitude.
    http://ecmweb.com/mag/electric_effects_harmonics_power_2/

    I'm not a power guy, but as I understand it, certain loads (especially big synchronous motors) aren't particularly fond of significant harmonics (they don't work properly, or dissipate significant heat).
     
  4. May 24, 2010 #3
    Harmonics are integer multiples of the fundamental frequency. As far as electricity is concerned, the supply voltage and load current may have harmonics, if the electric load behaves non-linearly. For example, a diode or a thyristor is an non-linear element, they don't draw current all the time, causing distortion in the current. As these currents flow through the line impedance, they create voltage drop and cause the load terminal voltage to be distorted. The harmonics always have a negative effect since their presence reduces the power factor, cause heating of transformers and conductors, neutral conductors have to be oversized in a three phase system, possibility of occurrence of resonance etc etc.,
     
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