Big Ferrite Transformer (fwd)

[Steven Roys <sroys@xxxxxxxx>]

---------- Forwarded message ----------
Date: Mon, 05 Apr 2004 11:51:33 +0930
From: Matthew Smith <matt@xxxxxxxxxx>
To: High Voltage list <hvlist@xxxxxxxxxx>
Subject: Big Ferrite Transformer

Hi All

<http://www.mss.cx/ferrite.jpg> shows a large ferrite transformer that I
acquired some time ago.  It was described as an "avionics transformer", although
I thought that aircraft ran on 400Hz with iron cores.  This is a big lump of
ferrite.  (See AA battery for scale.)

The whole thing weighs 1.5kg and the low-voltage winding is a pair of 3mm^2
conductors (bifiliar).  Turns ratio is 1:56, established by a rough calculation
of SQRT(L1/L2).   The HV winding is actually split into two spools.

Would anyone like to hazard a guess as to the power handling of a transformer
like this, assuming that I drive it at 40kHz?  (I'd like to go higher, but don't
want to be putting all my energy into making the ferrite hot ;-)

There seems to be a good few turns of paper between primary and secondary and,
considering the dual-spool HV side, would guess that it could take a reasonably
high voltage.  Should I just drop it in a tub of oil to be safe?

There's a temptation to run it off-line (340V from bridge-rectified 240V) but,
as my physics teacher was wont to say, I think that it would have a "short, gay,
merry life".

Thankfully, the core is held together with iron bands (not glue), so can be
disassembled and rewound if necessary.

Cheers

M

-- 
Matthew Smith
Kadina Business Consultancy
South Australia
http://www.kbc.net.au