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From: Chuck Simmons
Organization: You jest.
X-Mailer: Mozilla 4.61 [en] (X11; U; Linux 2.0.33 i586)
Subject: Re: Microwave oven from 110V to 220V
References: <3DA42F7E.C83136F3@nf.sympatico.ca> <3DA43808.60C7A155@webaccess.net> <3DA46076.D91BDAB2@nf.sympatico.ca>
Date: Wed, 09 Oct 2002 17:56:54 GMT
NNTP-Posting-Date: Wed, 09 Oct 2002 10:56:54 PDT
> Chuck Simmons wrote:
> > Terry wrote:
> > >
> > > Ahmdsamir wrote:
> > > >
> > > > Hi there
> > > > is it ok to use a transformer to run a microwave oven originaly for
> > > > 110V/60Hz , with a 220/[50Hz]?? i.e. does the mains frequency has any effect
> > > > on the operation of the microwave???
> > > >
> > > > thanks
> > > > ahmdsamir
> > >
> > > Possibly OK; although the internal transformer will be less
> > > efficient at 50 Hz. and so may get hotter especially with
> > > prolonged use. I don't think it will affect the control functions
> > > (push buttons/display etc.) if yours has that feature. What size
> > > and type is yours?
> > > But more to the point microwaves take a lot of power for brief
> > > periods so a pretty big separate transformer, or something, will
> > > be required to step down the 220 to 110!
> > > If you use a single winding auto transformer it will have to
> > > carry the total power required which can be anywhere from 600 to
> > > 1200 watts.
> > > If you use a 'bucking' transformer arrangement the secondary
> > > winding feeding the microwave and opposing the 220 volts so that
> > > it is 'stepped down' to 110, will have to be wound with
> > > sufficiently heavy wire to carry the total current required by
> > > the microwave; even though in this configuration the transformer
> > > will only have to handle half of the total power required by the
> > > microwave. Transformers of this size are not necessarily small or
> > > cheap!
> > By what enormously strange method of calculation do you get the result
> > that the ordinary transformer "will only have to handle half of the
> > total power?" Did someone change the laws of the universe while I was
> > sleeping?
> > Chuck
> > --
> > ... The times have been,
> > That, when the brains were out,
> > the man would die. ... Macbeth
> > Chuck Simmons email@example.com
> Not an 'ordinary transformer'. But one used in what is commonly
> referred to as a 'voltage bucking' arrangement' With voltage
> bucking the input to a a two winding 2 to 1 transformer is the
> 220 volt mains; the output is 110 volts. Instead of using this
> 110 volts to power the microwave directly; that is the entire
> load being transformed from 220 to 110 through the transformer
> the 110 volt transformer output is wired so as to oppose (or go
> against) the same 220 volts being presented to the input. Thus we
> have 220 minus 110 volts = 110.
> So, if you think about it, half of the power load of the
> microwave is supplied directly (as it were) from the 220 volts
> and the other half via the voltage opposing transformer. The
> proviso as mentioned is that a) the transformer secondary winding
> must be able to carry the total amount of current, in amps, that
> flows through it.
> What makes this a bit easier to understand is that we are, in
> this theoretical case, dealing with exactly half the voltage. But
> the idea of buck or boost applies to situations where one needs
> to only slightly reduce or increase voltages etc. e.g. one can
> boost up or buck down a mains supply by a few volts in order to
> get a piece of equipment to operate correctly or to test that it
> will continue to operate at reduced or increased voltage. Also
> the insulation of the transfomer secondary must also be able to
> withstand the maximum voltage impressed on it, namely 220 volts.
> Have fun?
Sorry. I flunked necromancy, wizardry and general witchcraft when I was
in school. I didn't even pass mind reading. Damned strange I got a
degree anyway. Maybe it doesn't count because I studied mathemagic.
I happen to like science fiction, however.
... The times have been,
That, when the brains were out,
the man would die. ... Macbeth
Chuck Simmons firstname.lastname@example.org
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