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Re: oil dielectric
Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Xyme3-at-aol-dot-com>
In a message dated 5/14/2002 1:16:24 PM, tesla-at-pupman-dot-com writes:
<< The oil actually keeps the coil cool by damping molecular
Having done some thermal design & studied transformer
design, I'd find that surprising.
The molecular movement he is referring to is particle bombardment. If the
coil was in a partial vaccum it would quickly disintergrate. In air, the
movement is retarded by the presence of other air molecules.
Oil, in a conventional
transformer functions in two ways:
You are certainly correct, non moveing oil is a good insulator.
Moveing oil would absorbe heat. In a large container, convection
currents would occur in the oil heated from the
eddy currents you mention below. I also agree that
The thermal effect is by being heated by hot spots
(core eddy currents, coil resistance losses), then flowing,
by natural convection, or, less commonly, pumped
circulation, to a cooler spot where it can dump heat.
Sometimes the cool spot is aided by heat sinks ('fins').
cf any text on transformer design.
> The way I wound the coil was to wind it on a 3.5" OD
> PVC pipe and then slide a 4.5" OD PVC pipe over it and seal
This makes me nervous.
> both ends. I left a quarter inch hole in the top plug and used
> something like a turkey baster to fill the coil with oil. When I
> was done, I sealed the small hole.
I say nervous because a sealed container, can, if heated,
even by a fault, 'rapidly disassemble': Explode.
Unlikely, probably, here, but possible. (Power
transformers can and have exploded, when not vented.)
> I like this coil so much I'm going to wind another one. This time
>I'll use finer wire if I can get some.