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Subject: Re: PSU's: Exceeding transformer rated current
Date: Wed, 8 Jan 2003 00:01:11 -0000
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"Richard" wrote in message
> Actually I think I see a part of the problem.
> In my example there are two situations. The internal resistance of the primary is
> Where the transformer supplies an ac current, ie say without any rectification, the
> transformer rated at 10v rms @ 1A supplying it's max rating has 0.5 watts
> in the internal resistance (I^2 x R; 1A x 0.5R) . Connect as half wave rectifier
> the available voltage for R load is 4v when dissipating 10 watts in R load and the
> current is 2.4A. Dissipation in R internal is 2.4A ^2 x 0.5R = 2.88 watts. So, we
> are supplying 10watts in both instances to a load, but greater copper losses where
> have used half-wave rectification. And that's assuming the 2.4A rms current, which
> would be 6.7892504A peak would not melt the wire.
Oh drat the current is supposed to be 2.5A rms in the half-wave circuit, not 2.4A
rms. That makes copper losses 3.125 watts as against 0.5 watts.
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