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Re: More Tuning/Debugging Next

Tesla List wrote:
> 
> >From Esondrmn-at-aol-dot-comSat Sep  7 09:40:34 1996
> Date: Fri, 6 Sep 1996 17:37:25 -0400
> From: Esondrmn-at-aol-dot-com
> To: tesla-at-pupman-dot-com
> Subject: Re: More Tuning/Debugging Next
> 
> In a message dated 96-09-04 01:12:22 EDT, you write:
> 
> << > If I remember correctly, you were using multiple oven elements for
>  > resistive ballast? try using fewer elements. This will reduce the
>  > dampening of your arc welders inductance.
>  >
>  >         jim
> 
>  All,
> 
>  Here, here, I second the motion.  We have struggled here in Richmond to
>  learn all this the hard way too.  On tape #8 1990 we finalize this maxim
>  for all to see.  The resistance is a must for all the above reasons with
>  pole type xfrmers.  Bill Richards ignited a lamp socket in his ceiling.
>  He also burned out a wall light switch.  Alex Tajnsek took out a stove
>  exhaust fan (caught fire).  The bunggy cord nature of the resitive
>  portion of the ballast mushes the response of the big inductor.  Gotta
>  have it for best operation!  I believe it was in 1990 that I wrote a
>  sysergistic tune paper for Harry Goldman.  This covered spark gaps, etc.
> 
>  Richard Hull, TCBOR >>
> 
> Jim and Richard,
> 
> Thanks for the advice.  I had been using three 2000 watt oven elements (each
> in parallel) in parallel with the welder which is ballasting the pole pig.
>  This is a 5 KVA pig that I have been running up to 7 or 8 KVA.  As I
> mentioned, with my recent changes in the primary circuit the gaps will not
> fire with the old configuration and the system would only work well with the
> resistive elements unplugged - i.e. welder only.  What would you suggest
> here?  Just trying two elements then one element in parallel with the welder
> and check system performance?  I have up to six or seven 2000 watt elements
> that can be used.  Is there any value in trying the elements in series with
> the welder?  I did try that in the old configuration and performance went
> down.
> 
> Thanks,  Ed Sonderman

Ed,

There is definately something interesting going on in your system!

What voltage rating is the "primary" of your 5 KVA pig? By any chance,
are you running 240 Volts into a 120 Volt winding to get 14.4 KV out of
a 7.2 KV pig??  You may be saturating your pig... When this occurs, the
output voltage will no longer be sinusoidal. The "tops" of the sinusoid
flatten out, and you may not be able to charge the caps to the voltage
necessary to break down the gaps. Jim's system saturates his pig, but it
seems to run OK (with perhaps some fairly high voltage spikes as the pig
comes into/goes out of saturation in series with the ballast...).

If you have an old 15 KV neon laying around, try tying the secondary of
the neon across the pig output, and scoping or taking a voltage
measurement on the primary of the neon while increasing the variac
setting. This is a "poor-man's" equivalent to a potential transformer.
If you see signs of significant "flattening" of the sinusoidal tops on a
scope, or any marked flattening of output vs input voltage, pig
saturation may be what you're fighting. 

A possible scenario:
When you remove the resistors, you reduce the real primary power being
dissipated in the core as well as reduce the damping on the ballast.
Near the zero crossings on the AC input, the pig comes out of
saturation, and the ballast can now "dump" its stored energy into the
secondary circuit, helping to charge the caps (with potentially large
voltage spikes??). Removing the resistors also reduce the depth of
saturation when the gaps do fire. This may allow more energy from the
pig primary and ballast to transfer to the secondary and to your cap.
Because of the smaller core size, this may be more of a problem on 5 or
10 KVA transformers than on Richard Quick's re-wired 25 KVA beastie.

Jim - could your MicroSim SPICE model be modified to simulate the
effects of pig core saturation?? 

Good luck, and safe coilin' to ya! ;^)


-- Bert --