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HV shock modeling for Tesla coils

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Terry Fritz

Sun Feb 25 2007, 04:22AM

Registered Member #393 Joined: Tue Apr 18 2006, 12:30AM
Location:
Posts: 297

Hi,

I recently pulled the PIRANHA SISG web site temporarily off-line until I could improve the safety warnings and data. Since PIRANHA's charging system can be "thrown together" very quickly, I am very concerned that "anyone" could make a powerful (too powerful) system without much "HV safety knowledge". With two old microwave ovens and a screwdriver, I could put it together in about 1/2 hour... The SISG gaps still serve an "entry barrier" for many, but that could change very quickly as fully assembled boards become common...

In studying its safety and possible risks, I ran across this very nice safety paper:

Page 4 has a simple human body model and a graph that "sort of determines" what various shock levels will do to a person. Such data is easy to simulate with a circuit simulator to find peak and RMS currents that make be delivered to a person in contact with various parts of a Tesla coil system. The "death vs. time" and levels that cause "fibrillation" as opposed to "just stopping" the heart are pretty well explained...

PIRANHA actually delivers far less power than I thought into various human fault loads (still easily deadly) but the added load is small on fuses and other conventional safety devices. The output arcs still stop, but the circuit "happily" fries the person instead...

So I was wondering if the human model in Figure 1 has a more accurate version for voltages in the 5,000 to 25,000 volt range? Also, if there is a larger graph like than in Figure 2 that would extend into the 20 amp range? The graph could be extrapolated for 2 orders of magnitude, but that might not be very good.

Hopefully, I can fairly well "predict" the effect of touching various parts of the system in an effort to convince people that they really need to be "super safe" and fully enclose and insulate the thing like "I did" in my design. I also must ponder the known deaths:

and what safety measures could be taken "today" to eliminate the possibility of those specific accidents from recurring.

It would be nice if systems like PIRANHA were not only among the easiest and most powerful Tesla coils, but also among the "safest"!!

There will be a "temptation" to "skip" the NST and low powered coils by the "newbee" especially if systems like PIRANHA are "easier and simpler" to make... I am not sure how to "empress" upon them the extreme dangers of such high powered state of the art things... An advanced high powered coil, but the simplest to make... It could be a very "deadly" combination... Have to figure out how to "fix that"

All thoughts, public and private, welcome

)) I guess it is time to push the safety warnings to "another level" now that we are getting "too good" at this stuff

Cheers,

Terry

BTW - Interesting reading:

Tom540

Sun Feb 25 2007, 07:37AM

Banned on 3/17/2009.
Registered Member #487 Joined: Sun Jul 09 2006, 01:22AM
Location:
Posts: 617

Well... I think you should call it the gargoyle, since it's got gargoyles on it.

Steve Conner

Sun Feb 25 2007, 11:37AM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

How about "For goodness' sake don't touch it while it's turned on"?

I think that is all the safety information you'll need. All of these graphs and predictions are kind of beside the point. It's already common knowledge that touching a circuit energized by a MOT carries a pretty substantial risk of death, so don't touch it, period. If touching an MOT is like playing Russian roulette, then calculating stuff like this just tells you how many bullets you're playing with, whereas common sense says not to put the gun to your head in the first place.

MOTs are possibly the most dangerous thing in the average HV hobbyist's arsenal (unless they are lucky enough to own a pole pig or plate transformer) and they should be treated with respect. Even unpowered, dropping one on your foot hurts

BTW, I think the Piranha is an excellent design, especially the fully enclosed primary. It's nice to know that if you do manage to battle your way through 4 foot long burning, jolting arcs to get to the bottom of the coil while it's powered, you won't be able to touch anything that could kill you

Not to mention that it looks awesome.

Terry Fritz

Tue Feb 27 2007, 05:24AM

Registered Member #393 Joined: Tue Apr 18 2006, 12:30AM
Location:
Posts: 297

Hi,

EVR had the "extended" info I was looking for

Fig 16 from "somewhere" is well extended into the regions of my "morbid" interests

No worries... The PIRANHA site is coming back on-line now "new and "approved""... For safety

The problem with the original site it that it was "pure raw technical"... "Assuming" those that "followed along" with the raw notes were as "bright" as "me"... Impossible!!

Harder for dummies to navigate, and now introducing "TM" and "patent pending" things to "control" the commercial boys from killing everybody with it....

The "raw notes ALL on-line" thing is cool... But it became "too easy" for "too many" to "follow"...

I hope the new thing will be all cool and "politically safety correct"....

Cheers,

Terry

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