Peter Chadwick wrote:
> Simpler is to connect an ammeter across the secondary, feed the
> primary from a Variac and wind up the Variac until trhe desired filament
> current flows. then leave it for a time and see how hot it gets.
The classic short circuit test.
> The
> probability is that most of the losses will be copper losses:
agreed
> leave it
> on full primary with open circuit secondary to get an idea of how much
> iron loss there is by the temp rise.
It's a long time since I did this, but the short and open circuit tests
give you copper and iron losses respectively. I think you can show that
theoretically copper_loss == iron_loss for maximum efficiency, but the
transformer would no doubt have been wound on a suitable former, rather
than one that is theoretically optimal.
I can't really see how you could determine the temperature rise too
easily by this.
It's not my area of expertise, but I would have thought a load resistor
a safer bet.
--
David Kirkby,
G8WRB
Please check out http://www.g8wrb.org/
of if you live in Essex http://www.southminster-branch-line.org.uk/
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