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From: "Phil Allison"
Subject: Re: PSU's: Exceeding transformer rated current
X-Newsreader: Microsoft Outlook Express 5.50.4522.1200
Date: Thu, 9 Jan 2003 15:10:02 +1100
NNTP-Posting-Date: Thu, 09 Jan 2003 14:59:42 EST
Organization: Telstra BigPond Internet Services (http://www.bigpond.com)
"John Woodgate" wrote in message
> Well, it's an interesting idea that the core 'walks' towards saturation
> by that means, but it is also necessary to take into account that the
> *secondary* current includes a far more substantial d.c. component,
> equal to the d.c. load current of course. I think that swamps any core-
> walking effect.
** I took a 15 VA E-Core and added a diode and 22 ohms resistor in
series across the 15 volt secondary. Running it at 200 volts AC (to
minimise the magnetising current) I monitored the primary waveform while
switching the half wave load on and off.
The current in the primary built up to its final value in just under
1 second, it took a very similar time to return to the oroginal value when
the load was removed.
I guess that means it took about 50 "steps" to walk the core into and
out of saturation.
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