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Re: Oil insulated secondaries (fwd) (Are they worth it?) (fwd)



---------- Forwarded message ----------
Date: Tue, 11 Sep 2007 03:38:53 -0700 (PDT)
From: Yurtle Turtle <yurtle_t@xxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Subject: Re: Oil insulated secondaries (fwd) (Are they worth it?) (fwd)

I just checked my cutsheet and I stand corrected. I've
always referred to my two 25 kV 125 kV BIL PT's as
"epoxy encapsulated" when in fact they're
"polyurethane resin encapsulated".

Let me restate my question...

Why not build the oil-filled secondary, but instead of
filling it with oil, encapsulate it with "polyurethane
resin"?

Adam

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

> 
> ---------- Forwarded message ----------
> Date: Mon, 10 Sep 2007 09:53:09 -0700 (PDT)
> From: J. Aaron Holmes <jaholmes@xxxxxxxxxxxxxxxxxx>
> To: Tesla list <tesla@xxxxxxxxxx>
> Subject: Re: Oil insulated secondaries (fwd) (Are
> they worth it?)
> 
> Epoxy coating is not about electrically insulating,
> it's about physically protecting and preventing the
> windings from sliding off.  That's it, really.  Oil
> does neither of these things, and is instead all
> about
> electrical insulation.  HOWEVER, whether it's any
> advantage at all depends on what other aspects of
> your
> design you hold constant, and given that most of
> these
> other aspects are usually controllable in such a way
> as to avoid the necessity of oil insulation, I'd
> have
> to agree that oil insulated secondaries are
> moderately
> to extremely silly in most cases.  They are
> undoubtedly "interesting" and "cool", though.  I
> loved
> the look of Terry Blake's coil, and decided to add
> my
> own twist".
> 
> All else being equal, I'd expect oil insulation
> would
> make the secondary less susceptible to secondary
> breakout, primary-secondary strikes, racing arcs,
> and
> internal arcing.  This, in turn, might permit the
> use
> of higher-than-average coupling, larger toploads
> (which would otherwise tend to encourage secondary
> breakout), and generally a bit more power, achieving
> a
> higher-than-average streamer-to-secondary length
> ratio.  But we'll see!!  Again, I doubt if it's a
> very
> practical way to accomplish these things, but it is
> nonetheless a fun twist.
> 
> Cheers,
> Aaron, N7OE
> 
> --- Tesla list <tesla@xxxxxxxxxx> wrote:
> 
> > 
> > ---------- Forwarded message ----------
> > Date: Sun, 9 Sep 2007 18:22:33 -0700 (PDT)
> > From: Yurtle Turtle <yurtle_t@xxxxxxxxx>
> > To: Tesla list <tesla@xxxxxxxxxx>
> > Subject: Re: Oil insulated secondaries (fwd)
> > 
> > I'm just curious why oil would be better than
> simply
> > potting it in epoxy. I realize it would look
> cooler.
> > Seems like an oil tight seal would be harder to
> > accomplish than one that only needs to hold up
> until
> > the epoxy hardens.
> > 
> > Adam
> > 



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