Not a bad point Jack. Ultimately most of the pigs are removed from the can
when used for amateur service. I don't know about the standards in the US
but here in Canada, these pole transformers had to have enough sheet
insulation between winding layers to meet the electrical requirements
*before* they were put in oil. The oil then just added a huge additional
insulation factor as well as providing the required cooling. This came from
a conversation I had with a design engineer at Ferranti-Packard (at one
time, one of the largest makers of pole transformers in Canada). So at
least in Canada, these things can be safely run dry. However the sheet
insulation is still subject to the same time/temperature/aging effects as
any other transformer so eventual failure is expected.
Phil
At 12:50 PM 12/20/2001 -0500, you wrote:
>One thing to remember..........the oil that these transformers normally
>operate in is not just for cooling, it is for insulation!
>The oil has good dielectric properties. I used a pole pig for some time and
>it ultimately failed after it arced internally to the core. I had removed
>it from the can and allowed the oil to drain off. Probably a good idea to
>leave the transformer in the can and keep it in oil to avoid such problems.
>Unfortunately, that makes for a rather large unit!
>73,
>Jack, W9GT
>----- Original Message -----
>From: "Geo Clute W7LFD" <gclute@attbi.com>
>To: <amps@contesting.com>
>Sent: Thursday, December 20, 2001 12:39 PM
>Subject: RE: [AMPS] HV Pole Pigs ++
>
>
> >
> >
> > I like the concept of "Dial-A-Voltage". Variac and pole peg mounted
> > in a 4 wheeled photo copier cabinet. Oh yes...an Edsel steering wheel
> > on the Variac.
> >
> > Still looking for the Edsel.
> >
> > Geo W7LFD
> >
> >
> > --
> > FAQ on WWW: http://www.contesting.com/FAQ/amps
> > Submissions: amps@contesting.com
> > Administrative requests: amps-REQUEST@contesting.com
> > Problems: owner-amps@contesting.com
> >
>
>
>--
>FAQ on WWW: http://www.contesting.com/FAQ/amps
>Submissions: amps@contesting.com
>Administrative requests: amps-REQUEST@contesting.com
>Problems: owner-amps@contesting.com
--
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