[sdiy] How to predict a tansformer's current capability?

[patchell]

    Another good predictor for transformer capablility is weight.  The VA
capacity is proportional to how much the transformer weighs in at.  In order to
get a certain amount of power, you have to have so much iron.  There are
variables, such as how the transformer is constructed...but, I don't remember
the rules of thumb I used to use...

Rob B wrote:

> There is something.. It has to do with wire gauges times the length of
> wire..You can find it on the net.
>
> Rob
>
> ----- Original Message -----
> From: "Glen" <mclilith at ezwv.com>
> To: <synth-diy at dropmix.xs4all.nl>
> Sent: Monday, December 24, 2001 1:37 AM
> Subject: [sdiy] How to predict a tansformer's current capability?
>
> > I have some assorted used power transformers that have been removed from
> > various types of equipment. I'd like to use some of these for projects,
> but
> > how do I predict what the maximum safe output current would be for a
> > transformer that I have little or no information about? I can determine
> the
> > primary and secondary windings with no problem. I can hook them up and
> > determine the output voltages with no load, but how do I determine the
> > maximum load the transformer should be subjected to? I'm more interested
> in
> > a "continuous use" specification, instead of a peak current rating, but a
> > peak current rating might be useful for some things as well.
> >
> > The transformers are a varied assortment. Some have multiple secondaries,
> > perhaps a few have multiple primaries. Some transformers have "step-up"
> > secondaries, but most are the "step-down" style.
> >
> > Do I just power one of them up, while increasing the load on the
> secondary,
> > and monitor the secondary's output voltage? (Perhaps I would stop
> > increasing the load, when the output voltage has dropped by some
> calculated
> > "safe" amount, whatever that amount might be, and declare the amount of
> > current flowing at that moment to be the maximum rating.)
> >
> >
> > Thanks for any assistance,
> > Glen Berry
> >

--
 -Jim
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