Transformer identification

[The Dark force of dance]

Y-ellow Y'all.
	While we're on the subject -and at risk of perhaps having missed part of
the thread that covered this- I have a transformer query. Something that's
been bugging me for years.

I have a 4 amp variac. This is driven by a 10 amp isolating transformer. In
fact my whole bench is isolated. Ideal for testing transformers. The thing
is that it's easy to find the transformer's voltage. How 'n' hell do you
find the current. Considering that despite the isolation transformer being
able to deliver 10 amps, it still has a slight amount of sag.

There's a place here that does recycled stuff. The guy's been selling
recycled transformers for years. He catalogs them and can work out the
total VA but I can't work out how he does it. I've seen his set up and it's
not all that different to mine? Unless he sacrifices one transformer to
identify a batch??

The only way I can do it is by guessing. Looking at the winding thickness
(If visible) and the core size. But that's a very rough guide. Any clues?

Thanks in advance.

Be absolutely Icebox.

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