Re: Lots of questions

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Arpit Thomas" <neko4-at-dodo-dot-com.au> 

And please have a look at some electrical flash burns pictures before you 
begin any high voltage project. That sort of stuff could easily. very 
easily, happen to you. If heart fibrillations don't kill you, the burns may 
well do.  A pole pig is overkill for an electric chair.
Its always best to start small and work your way up. Another poster here 
wanted to (start?) with microwave oven trsnsformers, which is also a bit scary.

take care, please

*********** REPLY SEPARATOR  ***********

On 21/01/2004 at 7:58 AM Tesla list wrote:

 >Original poster: Bart Anderson <classi6-at-classictesla-dot-com>
 >
 >Hi Newell,
 >
 >Glad to see you've joined up on TCML!
 >
 >You'll notice experienced coilers are very "leery" of new coilers diving
 >into pole pig transformers for a first coil because there are some "real
 >dangers" involved. I've already mentioned this stuff off-line, so you know
 >exactly where I stand on this issue.
 >
 >I HIGHLY recommend an NST transformer first. Build the coil. Use the NST.
 >Learn through doing. Then and only then go ahead and upgrade. If you get a
 >pole pig first, "you will use it", and without some experience with TC
 >operation (not only the transformers), you have much greater risk of life
 >and limb. I don't know your experience with electrical or electronic
 >components, assembly, and operations, but I would say the same thing to
 >anyone asking these questions. Although 3 have died in some manner with
 >Tesla Coils, no one I have heard of has died from advice off this List, at
 >least, not yet. The one that does is likely to be one who takes risks or
 >doesn't heed advice (may be one and the same). Consider this as coilers
 >watching out for one another. I know this next bit may sound morbid, but I
 >believe it's just a matter of time, and that scares me (and it could be
 >any
 >of us, not just new coilers). Let's face it, this is a "coil at your own
 >risk" hobby.
 >
 >More interspersed below:
 >
 >Tesla list wrote:
 >
 >>Original poster: "Newell Jensen" <pillar2012-at-hotmail-dot-com>
 >>Hello all,
 >>
 >>I am new to this process so I am trying to figure this all out, so please
 >>bear with me if these questions seem off course.
 >>
 >>I have been contemplating in my head what I would need to do if I did
 >>indeed in the future buy a pole pig.  One question is why don't people
 >buy
 >>pad transformers that have the same voltage ratings as a pole pig?
 >
 >Coilers use all different types of transformers. Some of the more common
 >types are NST's, MOTs, Potential, and Distribution. There are of course
 >others which can be used. Typically, cost, availability, and practicality
 >are key issues.
 >
 >>Also I know that some pole pigs can be bought with taps and I am
 >wondering
 >>if this is going to be benefical in the end.  The one that I saw allowed
 >>the pole pig to adjust to a level of + or - of 2% of it standard voltage.
 >
 >Yes, most have taps to change the step-down voltage for line regulation
 >(as
 >is their intended use, up on a pole). We typically set the tap to it's
 >highest output voltage.
 >
 >>The pole pig that I am refering to by the way is a 10 KVA 14.4 KV single
 >>phase pole mount transformer.
 >
 >Yes, 5 kva and 10 kva are common  VA ratings for those that do have pole
 >transformers and use them in this hobby.
 >
 >>  Also when somebody finally gets one of these I have read that they are
 >> going to have to ballast it with something like an arc welder to limit
 >> the current.  If this is right, how does one go about doing that and
 >what
 >> are the specifics involved with the voltage and so forth? Also a variac
 >> has been mentioned and how would this be included to the whole situation?
 >
 >The ballast is typically "inductive" current limiting. Pole mount
 >transformers are not internally current limited. In a short circuit
 >condition, these transformers can draw many times their rated current. The
 >percent impedance rating of the transformer is a rating of how beefy that
 >current can be. For example, my transformer is rated at 1.9% impedance.
 >1/1.9% = 52.6 x rated amps or 2,193 Amps! Thus, we limit the current.
 >
 >Welders are common for this purpose, but you may want to check out the
 >TCML
 >archives for details at pupman-dot-com. Variacs are also common and is what I
 >use. Between the voltage adjust variac and the transformer, I have
 >connected in series a large variac which must have sufficient current
 >capability for the current planning to be run. If the variac is large
 >enough, it can be connected in series without modification to the variac.
 >However, if the variac is border line, then a slot can be cut in the core
 >material to prevent core saturation. If it's too small, it will fail, and
 >probably fail shorted!
 >
 >>Does all of this together equal the "power module" that has been
 >mentioned
 >>as well?
 >
 >Terminology. From one view point, a power module can incorporate
 >everything
 >from the wall plug to the transformer. I like to separate these into
 >"supply" and "control module". The control module would be comprised of
 >the
 >voltage adjust assy, current limit/adjust assy, any added resistive
 >components (if used), possibly a second set of doublethrow breakers, power
 >switch/lights, volt and amp meters, and any safety devices such as deadman
 >switch/interlock, etc..
 >
 >>   Also if in the future if I was to finally get one of these what size
 >> should I make my coil, or would it matter since I have the control
 >module
 >> and can therefore adjust the power being supplied to the coil?
 >
 >A large transformer can control a small or large coil. Here's a thought.
 >Dr. R. is looking at having a professional transformer manufacturer build
 >some robust NST type transformers for TC use. I believe this will be a big
 >seller for a lot of coilers. I for one plan on at least 1 (maybe more).
 >
 >>   I have been thinking of also of constructing a HV cap like the MMC
 >that
 >> I have seen on the web.  I have heard that they are the best.
 >
 >Yes, they are ideal for TC use.
 >
 >>I also hear people always addressing how much the diameter of there
 >>secondary coil is and not the height of it.  Is there a certain height to
 >>what the secondary should be and also what about the size of the primary?
 >
 >Although you'll hear diameter mentioned, and even discussions on "ideal"
 >secondary h/d ratios, the ratio which is between 4:1 and 5:1 is the most
 >common. Other ratios will work, but there are many other aspects to
 >consider, least of which are the sparks off the top. It's nice to keep
 >them
 >far as possible from the primary, without going overboard on length. Some
 >have built tall coils and they worked fine. Others have had lousy
 >performance. Low h/d ratios get to be impractical.
 >
 >>   I know there are a lot of questions here and any help would be greatly
 >> appreciated.  Thanks
 >
 >Don't forget to hit the pupman archives.
 >
 >Take care,
 >Bart
 >
 >
 >>Newell