Re: buying a pole pig

["Tesla list" <tesla@xxxxxxxxxx>]

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

Your right, I ought to have thrown that measurement
out as "obviously bogus" when I took it a while back.
I suspect now that it probaly resulted from dirty
contacts.  I just now cleaned off the HV lugs of my
25kVA 14.7kV unit and clamped the probes on firmly.  I
measure about 30 ohms.

So it was I who slipped two decimal points ;-)  Thanks
for correcting that!

Regards,
Aaron, N7OE

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

> Original poster: Ed Phillips <evp@xxxxxxxxxxx>
>
>
> $50 for a pig ain't bad.  3.5' tall sounds *real*
> big,
> though.  There are some tall-'n'-slim pigs out
> there,
> though.  I've got a 15kVA unit that's about 3' tall,
> but I've also got a 25kVA unit that's scarcely 2'
> tall, so you never know.  I'll put in my guess at
> *at
> least* 25kVA, maybe 37.5 or 50.  Let us know! :-)
>
> Hard to dynamically test a pig without some big
> juice.
> Checking continuity is a good idea, though.  The LV
> windings ought to look almost like a short (less
> than
> one ohm), but the high side will probably have a few
> kOhms in it.
>
> Also, no matter the kVA rating, if it's less than
> 7200V I'd leave it alone.
>
> Regards,
> Aaron, N7OE"
>
>     That sounds like far too much secondary
> resistance.  Suppose it's
> a 25 kVa, 14 kV unit.  The secondary current at full
> load would be
> something like 1.8 amps.  If the i^2R loss was 1% of
> the total power
> (can't see it being much more than that) or 250
> watts, the
> corresponding secondary resistace would be around 78
> ohms.  For a
> 220V primary the corresponding maximum resistance
> would be about 0.02
> ohms if I haven't slipped a decimal point or two.
>
> Ed
>
>
>