Transformer help needed

"John"  wrote

Well I've traced what I think is a fault on my genny to an open
circuit 3 phase transformer. It's delta wired with quite thin primary
and thicker secondary. All 3 primary windings show open circuit with
my multimeter.
I've spend most of the afternoon whistling Old MacDonald's Farm to
myself as I stripped out the laminations removing E's and I's
interspersed with frequent oh's. I now have a pile of said E's and I's
and some wire on order to try rewinding the coils. Fortunately the
primary’s are on the outside.
Inevitably, 3 or 4 E’s broke during dismantling. I’m working on the
basis that 3 out of 120 aren’t significant and I will probably have
trouble getting them all back in anyway. The transformer’s on the
excitation circuit BTW.
Is there anything I should be aware of or should I give up now? Would
a rewind company do a much better job on a purpose made machine? If
so, is it worth just paying them to do it for me?


I'd recommend taking it to a rewind shop. You'll be extremely lucky if you
can wind as neatly as if it were done on a coil winder, which means that you
won't be able to fit the correct number of turns on the bobbin.

Above all, don't remove the failed windings - the rewind shop will need to
know the number of turns to perform the rewind.

If you have a specification for the transformer, you could think about
getting a new one made. They aren't that expensive.

wrote:


Give me some accurate dimensions and I'll see if any of our standard lam's wll
fit. Also need the thickness. 0.050" are standard 800/50 or 400/50 grade, there
are also higher-spec/thinner lams and GO (Grain Orientated) types.

Peter
--
Peter A Forbes
Prepair Ltd, Rushden, UK
peterforbes@prepair.co.uk
http://www.prepair.co.uk
http://www.prepair.eu

Thanks John and Peter for your help.
Unfortunately I don't have any details about the alternator, let alone
the excitation transformers
I spoke a rewind company and their price made me sit down.
I'm now looking at other ways around it.
Thanks again.

John