Re: Creepage distance? (was Re: 25 kV PT)

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Yurtle Turtle <yurtle_t@xxxxxxxxx>

That sounds plausible. These are epoxy potted, and
smooth on the outside. The reason I got them was due
to minor corona damage near the bushings. The space
heaters had failed in the gear, and they would get
moist under certain conditions. They cleaned up and
hipotted fine, but HP wanted new ones. So the creepage
distance was inadequate at 25 kV with a little
moisture and dust. And that was "only" 14.4 kV phase
to ground.

Adam

--- Tesla list <tesla@xxxxxxxxxx> wrote:

> Original poster: "J. Aaron Holmes"
> <jaholmes@xxxxxxxxxxxxxxxxxx>
>
> I just had another thought on this:  I wonder if the
> GE-recommended derating has to do with creepage
> distance on the *outside* of the transformer?  With
> one bushing grounded, depending on the shape of the
> PT, you may have just about halved the creepage
> distance.  Obviously, this would be a major concern
> in
> the wild, bad weather, etc., but in a nice dry
> garage,
> it probably doesn't matter at all.
>




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