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Varistor or Transient absorber

Discussion in 'Electronic Basics' started by Wong, Oct 10, 2003.

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  1. Wong

    Wong Guest

    Hi,

    I blown a power supply unit and need to replace this component, ZNR
    V10221U. Unfortunately I cant find the datasheet online and I think it
    should be a varistor or transient absorber. If you know this
    component, please help me and let me know.
    Thanks in advance for your big help !!

    regards,
    Wong
     
  2. Robert Baer

    Robert Baer Guest

    I would first look to see if Mouser carries it, as they have good
    refernces to manufacturers.
    Second place is DigiKey.
    Try them.....
     
  3. John Fields

    John Fields Guest

    ---
    I think you're right. With the prefix "ZNR", though, it's probably a
    Zener Transient Voltage Suppressor (TVS). I'd guess that "10221" stands
    for the clamping current (10A) and voltage (220V, with 22 being the
    first two significant figures and 1 being the number of trailing
    zeroes.) lot of MOV's and TVS's have a part number indicating the
    clamping voltage and current and yours seems to be a 10A 220V device.

    Google for Varistor or TVS and you'll get a lot of hits, then take a
    look at part numbers with 10 and 221 (or 220) in them to get an idea of
    whether what you have matches anything.
     
  4. Fred Abse

    Fred Abse Guest

    It's a Panasonic varistor, 10mm diameter, 220V threshold (turnover) - from
    the type number.

    Beware voltage ratings from different manufacturers, some rate on varistor
    (threshold) voltage, some on DC working voltage, some on RMS working
    voltage. RTFDS

    Digikey should have something comparable, if not the original Panasonic
    dingus.

    BTW, what makes you think it's faulty? It apparently isn't blown up if you
    can still read the number. To an ohms test with a meter it should appear
    open circuit. Below 220V, it should be as near O/C as makes no difference,
    above 220V, practically a short.
     
  5. ctsbillc

    ctsbillc Guest

    Great detective work.

    These high voltage protectors are usually MOV technology, especially if it
    is a big flat disk format.

    Regards,

    Bill
     
  6. It's what we call a MOV (Metal-Oxide Varistor), generically
    called a ZNR. You can replace it with a similar type
    of the same diameter disk (10mm? and rated for the appropriate
    voltage. If this is a 120VAC nominal supply, a 220V rated
    (221) varistor would be about right, but that's just a guess.
    (Varistors are sometimes rated by DC voltage, sometimes AC,
    and sometimes both!.

    Best regards,
    Spehro Pefhany
     
  7. It's what we call a MOV (Metal-Oxide Varistor), generically
    called a ZNR. You can replace it with a similar type
    of the same diameter disk (10mm? and rated for the appropriate
    voltage. If this is a 120VAC nominal supply, a 220V rated
    (221) varistor would be about right, but that's just a guess.
    (Varistors are sometimes rated by DC voltage, sometimes AC,
    and sometimes both!.

    Best regards,
    Spehro Pefhany
     
  8. It's what we call a MOV (Metal-Oxide Varistor), generically
    called a ZNR. You can replace it with a similar type
    of the same diameter disk (10mm? and rated for the appropriate
    voltage. If this is a 120VAC nominal supply, a 220V rated
    (221) varistor would be about right, but that's just a guess.
    (Varistors are sometimes rated by DC voltage, sometimes AC,
    and sometimes both!.

    Best regards,
    Spehro Pefhany
     
  9. (Spehro Pefhany) wrote in message

    <snipped>

    Sorry about the multiple copies, folks. Hazard with
    html-based newsgroup access, I'm afraid.
     
  10. N. Thornton

    N. Thornton Guest

    Hi

    If its in a mains filter feeding the unit, it should work fine without
    it, tho with a bit less protection and thus a bit less expected MTTF.
    Just so you know the options.

    Regards, NT
     
  11. Yes, and it's unlikely that the OP "blew" it, as he put it, if it's
    on the input side. This is typically the result of one too many
    transient into the MOV. One way you could affect this would be to put
    an inductive load such as a motor or transformer in parallel with the
    input of the SMPS and switch the two with a series switch. The typical
    failure mode, in any case, is a low resistance leading to very high power
    dissipation, burning, and, eventually, a high resistance, though the
    fuse may go before that happens.

    Best regards,
    Spehro Pefhany
     
  12. N. Thornton

    N. Thornton Guest


    Right. I'm having second thoughts tho: if its been cooked due to
    spikes, maybe it should be replaced before further PSU use after all.
    And not switched on with an inductive load in future.

    Regards, NT
     
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