[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]
Re: [TCML] 5.25" SRSG tesla coil suggestions on improving performance
JJ
Based on your time assessment, and further assuming a standard thermal
magnetic molded
case circuit breaker upstream, you are actually supplying 1.8 - 3X name
plate current. See
attached documents for Square D, I'm assuming a QO or equivalent thermal
magnetic MCCB
is being used for an OCPD. Refer to page 19.
http://static.schneider-electric.us/docs/Circuit%20Protection/Miniature%20Circuit%20Breakers/QO-QOB%20Circuit%20Breakers/0730CT9801R108.pdf
The horizontal axis is normalized current (i.e. 20A breaker at 20A current
would have a value of
'1' on horizontal axis, whereas vertical axis is time in seconds. The
curve band is minimum
and maximum time to trip at a given current. As an example using this
graph, at 3X rated
current the CB trip time can range between 3.7sec <= t <= 15 sec.
Take homes from this are:
1. You need to monitor current real-time on your machine.
2. You definitely need to ballast the transformers, you are supplying
40-60A to the MOT's.
3. As other posters have mentioned, your SG is the weak link at this
point, I'm highly
suspect of the acrylic wheel. High intensity UV will embrittle the
acrylic and it can
fail catastrophically without warning.
On Tue, Aug 6, 2013 at 9:59 AM, w5als <w5als@xxxxxxxxx> wrote:
> Hi
> First I am no expert at this, with that said looking at your
> pictures the tuning does not look to be right at 2.25 turns
> and I would think that MOT's would have to be ballasted to keep the
> current down. I have never use mot's before
> and may be totally wrong here. I hope some one else put there input in on
> this. I did not crunch the number on
> this for the tuning neither, I may be wrong but I think that may be a
> problem to.
> alton
>
>
>
> On 8/5/2013 8:59 PM, JJ Dasher wrote:
>
>> Hi all,
>> I'm new here. Although I've built a few coils in my past, I still
>> consider myself a newb coiler. I've never been the type to do things
>> mathematically perfect, and tend to wing it as I go along, which may be my
>> downfall here. For the past couple of years on and off, I've been working
>> on a 5.25" SRSG coil to use in a Halloween display. This is my largest
>> coil so far. You can see it in action here:
>>
>> http://www.youtube.com/watch?**v=2P3T5zuT9DI<http://www.youtube.com/watch?v=2P3T5zuT9DI>
>>
>>
>> and pictures of the guts here:
>>
>> http://imgur.com/a/0jgxR
>>
>>
>>
>> I'd like to get some constructive criticism and advice on getting this
>> running better. This trips my 20amp breaker after about 10-15 seconds of
>> running, so I figure about 2.2-2.6kw? I'm currently getting 36" streamers,
>> which I feel are somewhat weak. They are purple, and not very bright.
>> Specs:
>>
>> Large old powerstat variac salvaged from power equipment. Not sure on
>> exact specs, but I assume it should handle 30+amps with ease. Wired for
>> approx 150v boost.
>>
>> Dual MOT's (pulled from 1200w commercial MWs), currently unballasted.
>> 130uf of PFC caps behind them.
>> 180nf MMC cap built with 10 strings of 8x 942c20p15k-f's. 1m bleed
>> resistors installed.
>> SRSG is a 5" acrylic disc attached to a 1800rpm sync motor. 4 flying
>> electrodes for 120bps. Electrodes are 1/8" thoriated tungsten. Phase is
>> adjusted by twisting the motor in its mounts.
>> Primary is 3/8 copper tubing, slightly conical. Currently tuned at about
>> 2.25" turns
>> Secondary is 5.25" x 24" 22awg magnet wire with a couple of coats of poly.
>> Topload is a spun aluminum 4.5"x18" toroid.
>> All high current busses are 4awg stranded copper with large soldered lugs.
>>
>> The next improvement I plan is to upgrade to 1/4" tungsten electrodes.
>> The stationary electrodes currently glow red hot after about 5 seconds of
>> running, so I added a fan.
>> I'd love to get some bright long white snakes like I've seen from similar
>> size coils. Please advise!
>>
>> Thanks!
>> JJ
>>
>> P.S. There is normally a safety gap installed, It just wasn't in place
>> when I took those pictures.
>> ______________________________**_________________
>> Tesla mailing list
>> Tesla@xxxxxxxxxx
>> http://www.pupman.com/mailman/**listinfo/tesla<http://www.pupman.com/mailman/listinfo/tesla>
>>
>
> ______________________________**_________________
> Tesla mailing list
> Tesla@xxxxxxxxxx
> http://www.pupman.com/mailman/**listinfo/tesla<http://www.pupman.com/mailman/listinfo/tesla>
>
--
Dave Sharpe, TCBOR/HEAS
Chesterfield, VA USA
Sharpe's Axiom of Murphy's Law
"Physics trumps opinion!"
_______________________________________________
Tesla mailing list
Tesla@xxxxxxxxxx
http://www.pupman.com/mailman/listinfo/tesla