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Re: [TCML] power losses through GTO wire
On 2/17/12 7:08 PM, jeff mill wrote:
Hello Got a question Just got done building a 6" X28" secondary.
After the fact I did further reading and found that a 6 X 24 would
have been more closer to ideal. If, after testing I am not satisfied
with the results would there be a way to "buck" the upper 4" of the
coil temporarily without physically removing or cutting in and
tapping the windings ? Say a temporary 8" dia by 2" winding on a form
wired out of phase at the top ? Also I am bench testing this,
everything on my bench then two 12 foot of gto wire to the primary .
I am trying to figure my losses through the 15 ft of gto wire. Would
it be a dc loss or a loss at the operating freq 120khz. Another words
if it was calculated as a a dc loss then the resistance of the wire
would be much greater than the 8 turns on the primary and the loss
would be large but if it were calculated as an ac loss the impedance
of the primary would be around 16 to 20 ohms and the wire, being less
than an ohm the loss would be negligible ?
Really need some help here as I don't know if I should be judging my
results this way or wait until everything is mounted in my enclosure
and gto wires are much much shorter
where is the spark gap and capacitor?
That is, what's being carried over your HV cables? The AC from the
transformer, or is it in series with the L and C of the primary?
If the former, don't worry.. it's basically the DC loss, which is small.
If the latter, you need to figure out the AC resistance of the wire.
using the handy calculator here:
http://www.microwaves101.com/encyclopedia/calsdepth.cfm
I get skin depth of about .008" at 100kHz
Standard GTO15 is AWG14 stranded.. so it's about 0.06 inches in diameter
It's a rough approximation, but let's say that for AC resistance wise,
the "cross section slab" is 0.008x.06*pi call it 8*60/(1000*1000) * pi
or 480 /1e6 * pi
vs DC pi * (.06/2)^2 or 30*30/(1000*1000)*pi or 900/1e6 * pi
SO the AC resistance is going to be about twice the DC resistance. For
AWG 14, that's going to be 2.5 mOhm/ft DC resistance, so call it 5 mOhm
AC resistance/ft
You've got 15 feet (total, or one way?) .. in any case, something around
0.1 ohm total.
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