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Re: oil dielectric
Original poster: "davep by way of Terry Fritz <twftesla-at-qwest-dot-net>" <davep-at-quik-dot-com>
> I use oil in one of my secondaries. There is absolutely no
> heating. Even if there were, the plastic pipe the coil is
> wound on is more likely to burn than the transformer oil.
> The oil actually keeps the coil cool by damping molecular
Having done some thermal design & studied transformer
design, I'd find that surprising. Oil, in a conventional
transformer functions in two ways:
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.
In general, fine wire increases losses, limiting power,
and increases heating...