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More arc simulations




Hi All,
     I got the spice program to find the energy being dissipated in the 
three main losses in my model.  The results are as follows:

Initial energy in primary capacitor = 3.41 Joules
Energy into the arc = 2.097 J
Energy into the secondary losses = 0.144 J
Energy into the primary losses = 1.167 J

The secondary loss resistance is 270 ohms and the primary loss resistance is 
3 ohms.  These are found by measuring the ring down times of the real 
circuits and back calculating to find what resistance produces such a 
ringdown.

     Apparently, the secondary resistance and losses or not very significant 
in system power loss.  However, the primary losses are extremely significant 
as we have suspected since the beginning.  This suggests that the loss in 
the resistance of the secondary wire is of little concern (the DC resistance 
is 70 ohms in my coil).  However, the loss in the primary inductor's 
resistance, primary capacitor's series resistance, spark gap, and primary 
wiring is very critical.  This also supports the previous post showing that 
as the primary current is increased, the losses also increase dramatically.

     At 120 BPS, the power dissipated in the coil is simply 120 multiplied 
by the number of Joules from the above.  So from the initial 409 watts 
input, the arc is getting 251 watts of power, the secondary is using 17 
watts and the primary is burning up 140 watts (the high-Q ceramic caps, the 
primary coil, and wiring stay cool, so I suspect the spark gap is the vast 
majority of the loss).  The three ohm number for primary resistance came 
from when I used my multi-gap spark gap.  I bet my new sync rotary has less 
loss.  I will have to test this...

     The DC resistance of my secondary is 70 ohms but if I set the quenching 
to first notch with no breakout, it tests as 270 ohms judging from the 
ringdown time.  This does not quite make sense in the real world components 
and such.  I should probably set the primary resistance to the AC resistance 
of the coil and use a high value resistor from the output to ground to 
simulate the secondary's natural no-breakout ringdown time.  The losses 
would be the same but the model would then "look" more realistic since this 
resistance could represent corona or dielectric losses in the secondary's 
capacitance.  That would be about 10 watts.  This is not significant if the 
coil is arcing but this resistance does insure the model will track the real 
coil's performance under non-arc conditions.  Of course, the skin depth of 
the secondary wiring pushes the DC resistance up but I don't think it would 
be as high as 270 ohms.  I'll have to sit down and calculate this 
however....

The science goes on...  and no.. I haven't gone nuts yet! :-))


     Terry