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Re: homemade transformer

Original poster: "Jim Lux" <jimlux@xxxxxxxxxxxxx>


----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Wednesday, February 02, 2005 9:14 PM
Subject: Re: homemade transformer


> Original poster: "Mike" <mike.marcum@xxxxxxxxxxxx>
>
> Luckily pcb traces are usually wide and thin instead of round/squarish,
> which makes a nice surface area to release heat. Also, the traces aren't
> stacked on top of each other to multiply heat buildup like in a coil.
Which
> leads me to a question: anyone know how the world's biggest transformer
> (1500 MVA and 765-345kv according to Guiness) deals with the 7.5 MW of
heat
> (99.5 % efficient)? Seems like even oil would have a tough time unless it
> was the size of a city block. I hate to see that blow up like the one on
> Bert H.'s site.
>
Cooling design is a big factor in those big transformers.  As is mechanical
design (calculate the mechanical stresses from the magnetic field
sometime...).  They use hollow conductors and special winding patterns with
cooling passages.

For high power high speed generators they use hydrogen gas as the coolant
(high thermal conductivity, very low viscosity (low drag))

For folks interested in a great textbook on power electronics that doesn't
spend a huge amount of time on the gory details of the theory (but there is
theory), I recommend the book by Theo Wildi.  It's probably in a 4th edition
by now.   Great explanations of induction and synchronous motors,
transformer design, motor control, distribution, etc.  Lots of good diagrams
and photos as well.  http://www.wildi-theo.com/default.asp