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

[Rob B]

Well, and lets not forget the internal fuses that many power xformers have
built-in! I almost forgot about this.

Rob

----- Original Message -----
From: "patchell" <patchell at silcom.com>
To: <synth-diy at dropmix.xs4all.nl>
Sent: Monday, December 24, 2001 10:49 AM
Subject: Re: [sdiy] How to predict a tansformer's current capability?


>     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
> ------------------------------------------------
> * Visit:http://www.silcom.com/~patchell/
> *-----------------------------------------------
> *I'm sure glad Merry Christmas comes just once a year
> * -Yogi Yorgensen
> ------------------------------------------------
>
>