Re: 25 kV PT

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "J. Aaron Holmes" <jaholmes@xxxxxxxxxxxxxxxxxx>


--- Tesla list <tesla@xxxxxxxxxx> wrote:
>
> >The manual specifically says *NOT*
> to
> >ground one HV terminal unless operating at
> >substantially reduced voltage.  I forget the
> derating
> >factor.  It wasn't something obvious like
> 1/sqrt(2),
> >though.  It was even worse!  I assume this is all
> >because both sides of the HV are not insulated to
> 24kV
> >(or better) from the core.
>
> Hmmm - I wonder if they derate so much due to the
> risk of lightning strike or some other event that
> could push the envelope?...I know "our"
> applications are different, and have ltd duty
> cycles - the intended application remains connected
> 24/7 to hv.
>
> I really dont see the harm in grounding the
> inner-most side of the HV winding...I almost see
> it as advantageous - - I would be real curious to
> hear the rationale at GE for not connecting this
> way...
>
> Jack
>

I would be interested too, since it was my original
intent to connect the transformer that way.  Hard to
know which HV terminal is connected to the inner-most
HV winding.  Perhaps it correlates directly with the
phasing?  The thing is rated 200kV BIL and it's real
hard for me to believe that running with one ear
grounded would kill it, but 200:1 PTs are not everyday
finds!

When I'm all moved into my new house, I'll dig out the
manual and scan it.  I've continued to poke around on
GE's site, but can't find the softcopy.  The manual I
have was printed in the early 1980's, but the JVT-200
is still a production model.

Regards,
Aaron, N7OE