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From: John Woodgate
Subject: Re: welding a transformer core
Date: Thu, 19 Dec 2002 14:42:38 +0000
Organization: JMWA Electronics Consultancy
Reply-To: John Woodgate
NNTP-Posting-Date: Thu, 19 Dec 2002 16:53:47 +0000 (UTC)
X-Newsreader: Turnpike (32) Version 4.01 <5Z8C9wtxbnpWyFnyfFzqmVF739>
I read in sci.electronics.design that Gibbo
wrote (in <email@example.com>) about 'welding
a transformer core', on Thu, 19 Dec 2002:
>Someone mentioned only UK posters talking of overheating. This got me thinking.
>So I ran a MOT wth no load from a variac.
>At 250 volts within 10 minutes it was hot. Very hot. It was also pulling 3.2
>amps. I didn't bother measuring the waveshape or phase of the current to
>indicate whether it was saturation.
Well, it wasn't Scotch mist. Or microwaves! You can be assured that it
was saturation; the next experiment proves it.
>I then ran it at 220 volts. After 10 minutes it had hardly warmed. Mains
>current = 0.9 amps.
>UK uses 230 volts on paper. It's 240 volts in practice. Rest of Europe is 230
>volts on paper, 220 volts in practice.
>Looks like a saturation issue.
>I'm not saying this explains every instance and I don't have the time right now
>to look into it any further.
Saturation is a very significant factor, which I addressed in my post
listing the reasons for large temperature rises.
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
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