oil weight

From:  Bert Hickman [SMTP:bert.hickman-at-aquila-dot-com]
Sent:  Tuesday, June 23, 1998 6:51 AM
To:  Tesla List
Subject:  Re: oil weight

Tesla List wrote:
> ----------
> From:  Kevin Wahila [SMTP:kevinw-at-stny.lrun-dot-com]
> Sent:  Monday, June 22, 1998 8:19 AM
> To:  tesla-at-pupman-dot-com
> Subject:  oil weight
> ok, now i am at my local chemical disributor....they have pure mineral oil,
> weight 70.  is this too heavy?


Shell Diala transformer oils have a typical molecular weight of 261, so
pure mineral oil at 70 doesn't appear to be too high. Of more importance
is the viscosity, since thicker oils don't "wick" as well and may not
fully penetrate the interior of the cap. Any remaining air spaces can
then ionize under use. The resulting heat, ozone, and UV radiation will
break down the surrounding LDPE insulation with time, causing your cap
to fail. 

Typical transformer oil viscosity is in the range of around 12-66
SUS/cSt at 40 degrees Celsius. White USP mineral oil blends can come in
viscosities ranging from 32 - 370 SUS. Try to find a blend that has the
lowest viscosity - probably around 40 SUS. The higher the number, the
thicker the oil. 

Hope this helps!

-- Bert --