Re: [TCML] Are safety gaps necessary?

[mddeming@xxxxxxx]

Hi David,

Safety gap firing every 5-10 seconds does not necessarily mean?it is set too narrow. More likely it indicates? need for tuning adjustment. I would keep the strike rail until you can afford to pay for a couple of OH S**** episodes and then experiment without it.

Matt D.


-----Original Message-----
From: David Nelson <davidnelson11@xxxxxxxxxxx>
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>
Sent: Wed, 18 Jun 2008 11:36 pm
Subject: Re: [TCML] Are safety gaps necessary?


Gary, Bart, all.?
?
Given the advice of this list, I have set my safety gap (on a static spark gap system) and when the coil is running I get occasional firing of the safety gap, about 5 or 10 per minute. I was thinking this is all good and it does give me a certain peace of mind. Now given this latest discussion I am starting to think that I should be opening my safety gap out more. BTW I have a strike rail which does get hit occasionaly and it seems that the primary is very inlikely to be hit with the strike rail in place.?
?
Dave Nelson?
----- Original Message ----- From: "Lau, Gary" <Gary.Lau@xxxxxx>?
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>?
Sent: Wednesday, June 18, 2008 10:05 PM?
Subject: [TCML] Are safety gaps necessary??
?
I changed the Subj: line to reflect the topic...?
?
Way to stir the mud, Bart! It's good to make us examine our practices.?
?
I thought about your post quite a bit. Yes, it does seem hard to justify a separate static safety gap that is in parallel with the main static gap. I think we've had to do some hand waving and wiggling when we describe to newbies the procedure for separately setting the main and safety gaps. And I fully agree that a static gap is extremely unlikely to fail in the way that an RSG might. So I was about to join the heresy and agree that safety gaps appear to be redundant and unnecessary with a static gap.?
?
I slept on it and it dawned on me this morning. What happens when a streamer strikes the primary? If one exists, the 3-terminal safety gap fires, channeling the streamer's energy safely to RF ground. If one didn't have a 3-terminal safety gap, the only path for that streamer energy is through the NST. I think the NST would be happy that the 3-terminal gap exists!?
?
So I stand by the advice to use a 3-terminal safety gap.?
?
Regards, Gary Lau?
MA, USA?
?
> -----Original Message-----?
> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On?
> Behalf Of bartb?
> Sent: Tuesday, June 17, 2008 8:53 PM?
> To: Tesla Coil Mailing List?
> Subject: Re: [TCML] Chokes and Terry filters?
>?
> I think all of us are preaching proper gap spacing via NST and gap?
> setting (workbench approach) which eliminates the various electrodes?
> chosen. Another aspect to consider is that DC typically runs at about?
> 1.3 x Cres for his cap size. So he is taking advantage of some resonant?
> charging as far as bps is concerned. The static gap still clamps the?
> voltage regardless and I agree is the main problem with NST failures.?
>?
> If I were to weigh in on the filter discussion, I would say the chokes?
> are unnecessary with a filter. However, I have even pushed my gap?
> setting wide enough to kill an NST even with a Terry filter installed.?
> This is when I realized the safety gap was useless due to my gap setting?
> and sort of what drives me to stress the margin between safety and main?
> gap needs to be large enough to allow the safety gap to work, otherwise,?
> it's just a waste of labor and electrodes.?
>?
> I do push my transformers with what I can get away with. If it fails,?
> I'll just fix it or replace it. There are probably a few like me out?
> there on that subject. With that in mind, I've even been thinking about?
> doing away with the safety gap (my static gap coils only). The reason is?
> I have little margin and it's an annoyance when set correctly and?
> useless when it's not an annoyance.?
>?
> The fact is, the probability of a decently built static gap failing is?
> slim to none. So, what's the point of the safety gap in that type of > system??
>?
> Take care,?
> Bart?
>?
> Lau, Gary wrote:?
> > Indeed. I think the reason that DC has been successful in not killing > > NST's is his?
> conservative approach to keeping static gap width small. That, more than > using?
> any kind of filter, is the key to long NST life, and that's what we should > be?
> preaching. But human nature being what it is, the desire to increase > performance?
> has us opening the gaps to the max, and that's where Terry filters become > useful.?
> >?
> > Regards, Gary Lau?
> > MA, USA?
?
?
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