Order of magnitude of voltage of a conducting MOV

Discussion in 'General Electronics Chat' started by alphacat, Dec 26, 2009.

  1. alphacat

    Thread Starter Active Member

    Jun 6, 2009
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    When a MOV starts conducting, what is the order of magnitude of its voltage?

    Perhaps you could please attach a graph of the Conducting Voltage Vs. Current of a MOV?

    Thank you very much.
     
  2. bertus

    Administrator

    Apr 5, 2008
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  3. alphacat

    Thread Starter Active Member

    Jun 6, 2009
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    Hey,

    I looked at many datasheets but they never show there a graph of the conducting voltage or any indication on it.
     
  4. alphacat

    Thread Starter Active Member

    Jun 6, 2009
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    help please.
     
  5. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    Did you see the PDF of littlefuse on the page I gave you?

    Greetings,
    Bertus
     
  6. eng_mohamed ali

    New Member

    Dec 26, 2009
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    hey,nice
    coming soon
     
  7. alphacat

    Thread Starter Active Member

    Jun 6, 2009
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    Thank you for the attached pdf file.

    Yes, I saw it and also other datasheets of Littlefuse TMOVs.

    But i see no indication there on the MOV's voltage when its ON.
     
  8. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    In the datasheet there are curves for voltage of different MOV's voltages:

    [​IMG]

    for the 14 mm types and

    [​IMG]

    for the 20 mm types.

    Greetings,
    Bertus
     
  9. alphacat

    Thread Starter Active Member

    Jun 6, 2009
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    Oh, now i see why i though i didnt see it.

    I expected to have a very low "ON" voltage.
    Should the MOV's voltage be very low when its ON, since it shunts the Live/Neutral line to Earth?

    I thought that V_MOV(ON) would be very close to 0V.
     
  10. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    As you see a MOV is clamping and not shorting.
    If you want somethings that shorts, than you can make a crowbar with a thyristor/triac.
    (also in the links of the educypedia page).

    Greetings,
    Bertus
     
  11. alphacat

    Thread Starter Active Member

    Jun 6, 2009
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    Oh i see, thank you :)

    The voltage of a MOV with 400V clamping voltage will remain around 400V when its ON? (meaning, when its shunting current to Earth).
     
  12. bertus

    Administrator

    Apr 5, 2008
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    Hello,

    A MOV is acting like a sort of zener diode in two directions.
    The clamping voltage is dependend on the amount of over voltage.
    You can see in the graphs the voltage is a little bit higher when the clamping current is higher.

    Greetings,
    Bertus
     
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