The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
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 firstname.lastname@example.org
> 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 email@example.com
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup