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110V to 100V

Discussion in 'Misc Electronics' started by atasaka, Sep 5, 2003.

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  1. atasaka

    atasaka Guest

    I made the mistake of bringing a fuzzy logic rice cooker back with me from
    Japan and thought I could use a converter I already had at home but when I
    looked at the specs on the cooker, it says 100V, 1100W, 20A. My converter
    is rated for under 100W. So I found someone selling a 110V to 100V step
    down transformer at 1500VA and 15A max. Is 1500VA the same as 1500W?
    Will the 5A make any difference? I'm pretty clueless when it comes to
    this stuff but want to make sure I don't do anything that will damage the
    cooker since its electronics are quite complex as far as rice cookers go.
    The seller is not a dealer so he is not sure either. Any help would be
    appreciated. Thanks!
     
  2. DarkMatter

    DarkMatter Guest


    100V at 20A is 2kW. A single 120 volt line at 15 amps is only 1.8kW

    I'd find out what the thing really uses. Also, are you sure that
    your mains are at 110V? A 110 to 100 step down xfmr is only a 120 to
    109V conversion. The heating element in the cooker wouldn't mind so
    much, but the front end supply and control electronics for it may.

    Anyway, their 1100W claim doesn't jibe with their claim of a 20 Amp
    draw. One or the other is not correct. Either the unit only draws 1.1
    amps, or somebody doesn't know how to do the math in that japanese
    rice cooker factory. Maybe he was using fuzzy logic too! :]
     
  3. Mjolinor

    Mjolinor Guest

    AFAIK the tolerance of the power supply voltage SHOULD mean that it will
    work OK off 110. If it were mine I would certainly try it, maybe through a
    variac slowly if ti were very expensive but i am pretty certain it would be
    OK.

    That should get me a flaming :)
     
  4. Zak

    Zak Guest

    It shouldn't be an expensive transformer by the way. You could use a 110
    to 10 volt transformer of 150 (or 200) VA.

    The tricK: the primary is wired to your 110 volts. The secondary is put
    in series with your 110 volts, so that it subtracts (measure this...).

    The transformer is asked to deliver 15 (or 20) amps at 10 volts. That's
    a 150 to 200 watt transformer.


    Thomas
     
  5. atasaka

    atasaka Guest

    After reading your post, I looked at the rice cooker again and next to the
    20A in katakana characters, I think it reads "fuse" but I'm not too sure.
    Could this mean the rice cooker has a fuse built in that can handle up to
    20A? Thanks for everyone's help.
     
  6. Jerry G.

    Jerry G. Guest

    Your rice cooker will pull 11 Amps at 100 V and if you run it on 120 V
    it will pull about 13 amps. The reason for the 20 Amps being indicated,
    is that in Japan, the standard panel breaker for home kitchen appliance
    use is 20 Amps. Here in North America the standard is 15 Amps. As for
    the transformer, you should be okay with the 1500 VA unit.

    The cooker would probably work on 120 V, but it will be a bit hard on
    it. I would prefer to use the proper rated voltage. From 100 to 120 V
    there is a 20% difference. This is a lot for continuous use. Running
    the cooker on a higher voltage may definitely lower the life span of the
    unit.

    I am curious to know the company that made your rice cooker. Before
    Sony got in to the TV and electronics business, they were a rice cooker
    and small appliance manufacture. Infact, they were one of the best made.

    --

    Greetings,

    Jerry Greenberg GLG Technologies GLG
    ==============================================
    WebPage http://www.zoom-one.com
    Electronics http://www.zoom-one.com/electron.htm
    Instruments http://www.zoom-one.com/glgtech.htm
    ==============================================
    I made the mistake of bringing a fuzzy logic rice cooker back with me
    from
    Japan and thought I could use a converter I already had at home but when
    I
    looked at the specs on the cooker, it says 100V, 1100W, 20A. My
    converter
    is rated for under 100W. So I found someone selling a 110V to 100V step
    down transformer at 1500VA and 15A max. Is 1500VA the same as 1500W?
    Will the 5A make any difference? I'm pretty clueless when it comes to
    this stuff but want to make sure I don't do anything that will damage
    the
    cooker since its electronics are quite complex as far as rice cookers
    go.
    The seller is not a dealer so he is not sure either. Any help would be
    appreciated. Thanks!
     
  7. Mjolinor

    Mjolinor Guest

    I thouhght the original post said he wanted to run it from 110 volts but I
    can't find it to check?
     
  8. Mjolinor

    Mjolinor Guest

    I must have missed the bit where he said he was in North America as well.
     
  9. Steven

    Steven Guest

    brrr. Wrong answer.
    100V at 20A is 2kVA and has to be multiplied with cos(phi) to get real power
    (in W or kW).
    For resistive loads cos(phi) = 1, so then -- and only the! -- the 2kVA =
    2kW.
    If cos(phi) = 0 (pure inductive or capacitive loads) the 2kVA = 0W. Nothing,
    zilch, nada
     
  10. DarkMatter

    DarkMatter Guest


    It is a purely resistive load, dipshit.
     
  11. Given that rice cookers today are pretty inexpensive, and power
    converters are not, I tend to believe that this guy would be well
    advised to simply purchase a new rice cooker!

    Harry C.
     
  12. Maybe it uses a 100VAC 20 amp heating element with a TRIAC in series,
    which never allows the full continuous 20 amps thru. I.e. it's really a
    PWM controlled heater. And it might actually draw 20A peak for
    fractions of a second.
     
  13. Harry Conover wrote:
    [snip]
    Another thought. Advertise that you have a rice cooker that you brought
    from Japan recently and you're looking to trade for a U.S. one for
    someone who is going to Japan. Equivalent make, model, capacity, etc..
     
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