From: John Woodgate
Subject: Re: Step Down POwer Transformer
Date: Thu, 5 Dec 2002 13:27:55 +0000
Organization: JMWA Electronics Consultancy
Reply-To: John Woodgate
NNTP-Posting-Date: Thu, 5 Dec 2002 13:40:11 +0000 (UTC)
X-Newsreader: Turnpike (32) Version 4.01 <5Z8C9wtxbnpWyFnyfFzqmVF739>
I read in sci.electronics.design that email@example.com wrote (in
) about 'Step Down POwer
Transformer', on Thu, 5 Dec 2002:
>Joseph Goldburg wrote:
>> Hi All,
>> If I have a transformer 240VAC input 30v AC output at 500mA max.
>> And I use this transformer with 120vAC input which should give 15v at
>> 1amp. Right ?
>> What other effects should I look out for?
>The core will saturate at the same winding current, so you won't get
>more than 500ma out.
Current has NOTHING to do with increased saturation!!! In fact, if you
COULD get more than 500 mA out, ***without overheating the winding***,
the induction in the core would be lower than at 500 mA.
LEARN BY HEART:
Current heats, input voltage saturates, output current DE-saturates.
All that happens if you use a transformer with a lower input voltage
than the design value is that you pay a penalty in size and weight.
(Unless the input voltage is only a few percent of the design value,
when you may get 'bottom bend' effects, increasing leakage inductance.)
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk
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