[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: [TCML] Series Transformers

It probably could be done with a rotary, but it would certainly be an unconventional rotary. A sucker gap is good, but at the large cap size discharge energy, it's likely to be a problem. And due to the low voltage, increasing electrodes within the sucker gap has the same problem as the rotary. This is also not a good system for a standard hyperbaric gap. Hmmm..... Well, maybe a large surface area quench gap would work? 

An interesting problem! SISG comes to mind for some odd reason  ;-) .

Bart

Lau, Gary wrote:

My experience to date has been strictly with NST's, so take what I say with a grain of salt.  But the experience of others as reported on this List is that static gaps perform poorly with high current transformers.  Yes, I suspect that quenching will be the issue.

I would fear that a rotary gap would need its electrodes set precariously close, especially since the total gap needs to be divided into two segments.  But you didn't hear me say that it can't be done!

Regards, Gary Lau
MA, USA


-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
Behalf Of Phillip Slawinski
Sent: Wednesday, June 18, 2008 8:11 AM
To: Tesla Coil Mailing List
Subject: Re: [TCML] Series Transformers

I have already built a sucker gap, and it seemed to do a decent job
quenching.  This of course was with a .013 mfd cap.  I suppose when the full
1mfd + cap is hooked up the quenching will worsen?  Why do you say a rotary
gap is probably not advisable, electrode spacing has to be too close for
comfort?

On Wed, Jun 18, 2008 at 6:41 AM, Lau, Gary <Gary.Lau@xxxxxx> wrote:


2970V @800mA will be challenging.  Despite many who thought 4kV is too low
for a coil, I built a very efficient coil using a 4kV/20mA NST, using a
single static cylinder gap.  While it may be possible to get a static gap to
work at 2970V, the 800mA part may be difficult to quench.  At that low a
voltage, an RSG is probably not advisable.  You would also need a very large
cap to utilize the full potential of that power supply.

Regards, Gary Lau
MA, USA


-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On
Behalf Of Phillip Slawinski
Sent: Tuesday, June 17, 2008 9:21 PM
To: Tesla Coil Mailing List
Subject: Re: [TCML] Series Transformers

I have a nice variac 20A rated and 0-270V output with 120V in.  I was

able

to wire them in series and ran them up to 2970V @ 800mA.  Is 2970V too

low

to run a TC efficiently?

On Tue, Jun 17, 2008 at 5:13 PM, David Speck <Dave@xxxxxxxxxxxxxxxx>

wrote:

OK, Phil,

Looks to me like you want to step 110 VAC to perhaps 1100 VAC.

If they are identical transformers, then their internal polarities are
probably the same.  (But you can't count on that!)

Wire the two primaries in parallel.  Connect the high voltage output

end of

one transformer secondary to the low voltage end of the other

secondary.

 Power up the pair with a Variac set on a very low voltage, say one

volt.

 Measure the voltage from the low end of the first transformer

secondary to

the high end of the second transformer secondary.  If you have the
connection right, then you should see something like 11 volts.  You can

then

crank up the Variac voltage slowly to confirm that you see a

corresponding

increase in the output voltage at the high end.  Remember that Variacs

do

not provide any line isolation, and even at a one volt output, the

"hot" end

of the Variac output is still at line potential and can deliver a

lethal

shock.
If you don't see any voltage, check the output across each of the
transformers, to make sure that one of them is not open.  If both are
putting out about 5.5 volts individually, then you have the secondaries
connected wrong.  Just swap the link between the two secondaries to the
opposite secondary pin on one transformer (with the power off!) and

recheck.

A small word of warning -- many digital voltmeters (both cheap and
expensive) can give spurious readings when used to measure unloaded
transformers.  You may get much more sensible readings if you parallel

a 1K

to 10K ohm power resistor across the inputs to your voltmeter.  I once
wasted a half a day trying to figure out the transformer of a bandsaw

blade

welder with a good Fluke DVM.  The readings were all over the map, and

often

inconsistent and unrepeatable.  Putting a load resistor on the meter

made

everything work out sensibly.
1100 VAC isn't going to help you a lot for TC work.  You might be able

to

get away with seriesing 4 transformers for 2200 volts, but at this

point,

you will begin to stress the insulation between the windings and the

cores.

 I've read of 4 and 6 MOT series strings, but the outer transformers on

the

6 MOT strings had to be run under transformer oil to prevent winding to

core

voltage breakdown.  OTOH, the power output of a 6 MOT string (~12 KVAC

at

500 mA, if you use big MOTs), can compare favorably with a 5 KVA pole

pig,

just not so nice and compact, but nearly free, if you can find the

MOTs.

HTH,
Dave


Phillip Slawinski wrote:


Step Down transformers run in reverse.  The transformers have taps for
neutral 100V 110V on the primary.  On the secondary neutral  420 480

550.

On Tue, Jun 17, 2008 at 1:39 PM, David Speck

<Dave@xxxxxxxxxxxxxxxx>

wrote:




Phil:

What kind of transformers?

You can't series NSTs, 'cause they are center tap grounded.  You can
parallel them for more current, though.

Dave

Phillip Slawinski wrote:




Does anyone know of a way to wire two transformers so that they are
oppositely phased?


 _______________________________________________

Tesla mailing list
Tesla@xxxxxxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla


_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla

_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla


_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla

_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla


_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla