Re: Rotor SG

["Bert Hickman" <bert.hickman-at-xxxxxxxxxx> (by way of Terry Fritz <twftesla-at-xxxxxxxxxx>)]

Josh,

Similar to a welding arc, the main spark gap generates significant
amounts of short and long-wave ultraviolet (UV) radiation. This tends to
degrade most plastics, causing broken bonds and crosslinking. Plastics
that are intended for outdoor use contain additives which help them
better resist the effects of UV. UV damage can usually be seen as a
yellowing of the plastic, embrittlement, and cracking. This is very
often seen when PVC pipe is used to house static spark gaps, and can
ultimately result in a dark brown surface layer and significant
reduction in mechanical strength. Similar results can be seen with
Polypropylene and Polyethylene, resulting in significant reduction of
flexibility and embrittlement. Greg Leyh observed similar effects on the
Glass Epoxy structural members and insulator supports in the huge rotary
spark gap used in his 130 KVA system, Electrum: 
http://www.lod-dot-org/electrum.html
 
Polycarbonate (Lexan) also undergoes yellowing under UV radiation, but
in this case the UV reactions appear to be more cosmetic than
structural.  Lexan is an ideal material for rotary containment, since it
will continue to provide operator protection from rotary failures even
if it may yellow a bit from the spark gap's UV flux.   

Good luck in your studies!

-- Bert --
-- 
Bert Hickman
Stoneridge Engineering
Email:    bert.hickman-at-aquila-dot-net
Web Site: http://www.teslamania-dot-com

Tesla list wrote:
> 
> Original poster: "Josh" <t_coil-at-hotmail-dot-com>
> 
> I was curious if anyone who has build an enclosed Rotor SG (or any spark gap
> for that matter) has had any problem with the gases produced or UV light
> turning your acrylic or lexan enclosures yellow?
> 
> I am working on a synchronizer for a Rotary SG powered by an ATMEL AT90S2343
> eight pin microprocessor.  And I want to get all the information I can about
> enclosure types.
> 
> Any help will be useful.  When I am finished I may even post the source code
> for the chip and a layout of the design so that any one may utilize the power
> of synching your RSG.  I may also sell preprogrammed chips for 5 to 10 bucks,
> just enough to cover the price of the chip and shipping.  I'm not in this for
> the money, I find it a very fascinating hobby and learning experience.
> 
> I am new to this list but not to HV.  I am 19 years old and studying at
> Washington University in St. Louis, MO.  I am majoring in Electrical
> Engineering, obviously.
> 
> Once again any help would be appreciated, I will remember it in the future!
> 
> Happy Coiling,
> Josh