Re: input transformer trouble

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

Original poster: "Gregory Hunter by way of Terry Fritz <twftesla-at-qwest-dot-net>" <ghunter31014-at-yahoo-dot-com>

Hi Andreas,

MOTs are a pain in the neck (please forgive the
Americanism).  If you wire 4 MOTs with their
secondaries in series and their primaries in parallel
with the 240V mains, they are going to draw lots more
than 16A.  Probably 30-50A is a more realistic
expectation.  If you wish to draw only 16A, you will
need some external current limiting (ballast).  A 5th
MOT with its secondary shorted to its own core and its
primary in series with the 4 MOTs would make a
suitable ballast.  You might want to consider a twin
MOT power supply with voltage doublers to cut down on
the current draw.  It's simpler than it sounds.  See
my site and my link Marco Denickolai's site for
details.  Marco used Euro MOTs to build his supply,
and my supply is a copy of his, so you might want to
start with his diagram & description.  I've got a link
to his site on my home page.

Regards,

Greg
http://hot-streamer/greg

--- Tesla list <tesla-at-pupman-dot-com> wrote:
> Original poster: "Andreas by way of Terry Fritz
> <twftesla-at-qwest-dot-net>" <jolly-at-husum-dot-net>
> 
> i am a new coiler and trying to start with 4 MOTs
> and lots of 125V 18uF
> capacitors (i got 900 of them due to a failure in my
> first calulation,
> but no big deals because all 900 together were about
> $20). my first test
> of the transformer (secondary in series) woked but
> not as i expected. so
> i connected only a single MOT to my power line which
> gives me about
> 1850V. my power line is 230V. here is my problem:
> 
> all 4 MOTs have a power consumption of 8 Amps with
> secondary open. one
> MOT draws 2 Amps. i want to build a tesla coil of
> 2400 Watts power
> consumption. (to make it running on a single phase
> with 16 Amps max.).
> my single MOT draws 2 Amps even without getting warm
> (not in 30
> seconds)!
> 
> then i connected my 12-22 multi gap and some of
> these capacitors in
> series (128=0.14uF) to see how much current it draws
> then. when my multi
> gap is too far appart (no sparks) it draws 5 Amps (3
> Amps more), which
> seems pretty ok.
> 
> when i reduce the size of my gap, my single MOT
> draws about 6 Amps,
> which i do not understand yet. if i get them closer
> together (the sparks
> get smooth), i draw about 15 Amps from my power
> line.
> 
> here are my questions:
> 
> 1. why does my MOT draws 2 Amps?
> 2. how do i calculate the amount of "more power"
> when using a sparc gap?
> (noone talks about that.)
> 3. my goal is to use all 4 MOTs (>=600VA each) to
> make 7400 Volts and
> 2400VA to run a tesla coil at about 1000000 Volts.
> (all formulas i found
> say that i get 1000000 volts with a 2400VA input
> transformer) anything i
> might not have thought of?
> 
> i had no probs of putting 4 MOTs in series. my
> calculated resonance
> frequency will be about 100KHz. the size of the
> secondary will be about
> 40 inch high and 10 inch diameter.
> the thing is to make it running on a standard power
> plug (230V 16A in
> germany) to be able to show it my grand parents when
> i visit them :)
> 
> mfg...
> 
> andreas
> 
> 
> 
> 
> 


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