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From: "Phil Allison"
References: <firstname.lastname@example.org> <email@example.com> <8e+6RgBNico9EwL3@jmwa.demon.co.uk> <firstname.lastname@example.org>
Subject: Re: Doubling wallwart power rating
X-Newsreader: Microsoft Outlook Express 5.50.4522.1200
Date: Wed, 9 Oct 2002 09:37:52 +1000
NNTP-Posting-Date: Wed, 09 Oct 2002 09:26:03 EST
Organization: Telstra BigPond Internet Services (http://www.bigpond.com)
"Tony Williams" wrote in message
> Best efficiency is when iron losses = copper
> losses, but never possible at 50Hz. Or is it?
> I do believe that this method of designing/using
> transformers is an attempt to get the no load
> iron losses near to the full load copper losses.
** Seemsw to me the iron loss is small compared to copper loss.
> After all who says that a transformer should only
> run hot at full load..... if it runs as hot at no
> load, then this must be a condition of minimum
> iron in the design.
** My assesment is that the makers are just trying to get the biggest
bang for their buck. By that I mean meeting the required spec with the
Saturating the core heavily leads to improved output voltage
regulation since the primry turns and resistance is well down compared to
usual transformer practice. So a smaller core can be used or more output
obtained from the existing one.
The reducing primary VA with increasing secondary load is a nice
anomaly to have a student explain.
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