[AMPS] Transformer Current ratings

Steve Thompson g8gsq@qsl.net
Mon, 17 Dec 2001 08:03:40 -0000



-----Original Message-----
From: Peter Chadwick <Peter.Chadwick@zarlink.com>
To: amps@contesting.com <amps@contesting.com>; 'Bill Smith'
<ko4nrbs@yahoo.com>
Date: 17 December 2001 07:49
Subject: RE: [AMPS] Transformer Current ratings


>
>One other trick to check a transformer is to measure the resistance of the
>secondary winding. Then using a variac, connect an ammeter across the
secondary,
>and wind up the primary volts until the secondary current is the desired
value.

Don't forget to use the PSU designer program to get an estimate for the RMS
current at your desired dc output current, and use the RMS value for this
test. Multiplying the dc current by 1.4 will underestimate the heating in
the transformer by anything up to 10x.

Steve


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