The Cyber-Spy.Com Usenet Archive Feeds Directly
From The Open And Publicly Available Newsgroup
This Group And Thousands Of Others Are Available
On Most IS NNTP News Servers On Port 119.
Cyber-Spy.Com Is NOT Responsible For Any Topic,
Opinions Or Content Posted To This Or Any Other
Newsgroup. This Web Archive Of The Newsgroup And
Posts Are For Informational Purposes Only.
Subject: Re: PSU's: Exceeding transformer rated current
Date: Wed, 8 Jan 2003 00:01:11 -0000
NNTP-Posting-Host: pc2-heck1-4-cust111.hudd.cable.ntl.com (126.96.36.199)
X-Newsreader: Microsoft Outlook Express 6.00.2800.1106
"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.
Go Back To The Cyber-Spy.Com
Usenet Web Archive Index Of
The sci.electronics.design Newsgroup