When I built my pole pig powered coil I also built a SRSG designed for 240 BPS at 60 Hz. I also built one of the electronic variable phase controllers based on a large variac and capacitors which you can read about elsewhere. The phase controller allows the phase to be varied electrically from 0 to almost 90 degrees confirmed through testing. My motor has 2 flats ground on the armature for synchronous operation. Using my oscilloscope and an LED sensor, I carefully aligned the SRSG to fire at phase angles of 0, 90, 180, and 225 degrees without the use of the electronic phase controller. My intention was to then use the variable phase controller to experiment with different firing phase angles off of nominal.
I then operated the coil without the phase controller and noted the spark length and characteristic. I then used the phase controller to adjust the phase angle. To my surprise, the phase angle made no discernible difference in the spark length or characteristic. I tried offsets of 0 to almost 90 degrees. My only conclusion is that the phase angle makes little difference at 240 BPS at 60 Hz at least at the 4.8 KVA power level that I am currently using. This makes me think that the easier-to-build ARSG might be a better choice at the 240 BPS rate for high power coils.
Steve
----- Original Message -----
From: "phil" <pip@xxxxxxxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Tuesday, July 10, 2018 3:57:10 AM
Subject: Re: [TCML] SRSG 200bps or 100bps choice
Do you why that would be the case? Ive never built a rotary gap coil and
would like to know more :)
Thanks!
Matt
On Sun, Jul 8, 2018, 4:22 PM <pip@xxxxxxxxxxx> wrote
Do you why that would be the case? Ive never built a rotary gap coil and
would like to know more :)
Thanks!
Matt
------------------------------------------------------------------
Matt.
My observations were based on just that - observations. We, that is
myself and another UK coiler, have ran both SRSG and ARSG coils, as well
as statics and each tends to display different streamer characteristics,
although it's mainly the rotary coils where this is noticeable.
A very good explanation on RSG and static gaps and the pros and cons is
at Richie Burnett's excellent web site, as my own brain cells have lost
their edge lately on the more technical aspects.
Richie's site is at www.richieburnett.co.uk/ and there is info on my
own site http://www.hvtesla.com. Also try the archives on here.
Basically once you've decided on either a static or rotary (RSG) gap,
then if you choose rotary you then have two flavours: SRSG or ARSG. The
latter Asynchronous rotary is quick and easy to build, while a
Synchronous rotary is more efficient at lower bps rates, but also a lot
more work to achieve, needing motor modification and careful control of
the phase using some form of phase control, and also care is needed with
the MMC size**. Probably only worth it if you want to squeeze every last
bit of performance out of a coil.
An SRSG at 100/120 bps (50 or 60Hz) can be particularly challenging as
you can then run into some very high resonant voltages if you get the
phase wrong. This is now thought to behind the damage at my other recent
posting:
https://www.pupman.com/listarchives/2018/Jul/msg00019.php ; entitled "Bad
strike to a 12 inch traditional coil (somewhat
terminal)"<https://www.pupman.com/listarchives/2018/Jul/msg00019.php>
To sum up:
Static: - Easy to build, generally suited up to 6 or 7kW (yes I know
others have ran twice that)
Rotary ARSG:- Easy to build, handles power better than a static with
theoretically no upper level for hobby coiling.
Rotary SRSG:- Lot more work involved, most efficient up to 300bps
(particularly at 200/240 bps) if pursuing 100% power, harder to run,
handles power as ARSG above.
People often try SRSG but don't get success because MMC size and phase
are critical. (See "resonant charging" on Richie's site)
I've left out 'triggered gaps' another thing that used to interest me,
but never got around to trying.
Good luck experimenting.
** Note: MMC resonance is affected by both mains frequency AND the bps
rate if using synchronous. Richie calls it resonant charging and has an
old TCML post reproduced here with the graphs he refers to (now dead links):
http://www.hvtesla.com/richie.html
Phil
On 09/07/18 15:27, Matthew Sweeney wrote:
> Do you why that would be the case? Ive never built a rotary gap coil and
> would like to know more :)
>
> Thanks!
>
> Matt
>
> On Sun, Jul 8, 2018, 4:22 PM <pip@xxxxxxxxxxx> wrote:
>
>> If you have wondered on how each perform, especially in their streamer
>> behaviour, have a look here:
>>
>> https://youtu.be/Sm8SoFmnlLM
>>
>> There is a general feeling that 200bps will give marginally longer
>> strikes, while 100bps is better for ground strikes.
>>
>> Phil T
>> _______________________________________________
>> Tesla mailing list
>> Tesla@xxxxxxxxxxxxxxxxxx
>> https://www.pupman.com/mailman/listinfo/tesla
>>
> _______________________________________________
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> Tesla@xxxxxxxxxxxxxxxxxx
> https://www.pupman.com/mailman/listinfo/tesla
--
Regards Phil www.hvtesla.com
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