# Re: Fwd: RE: [TCML] Rotory STATIC Gap

```Hi Scot,

```
I built a rotary once comprised of small electrodes (3/16"D) protruding out about 1.5". The electrodes were screwed into one side of the disc. The disc was metal. The problem I had is that when the voltage went high enough, the arc would travel down the electrode and across the wheel to the other electrode (or attempt to). This was "drawing the arc" mechanically from one electrode towards the next. When I realized what was occurring, I decided to use an insulated disc (no copper ring) and let the arc pass through the electrode placing my stationary electrodes on each side of the disc rather than on the same side. I think my problem was mainly that quenching was poor. I suspect quenching is also part of your problem here, but not sure.
```
```
Are you able to arc the distance if the rotary is not spinning and the rotary electrodes are positioned equal distance away from the stationary electrodes? Giving that a quick test may help determine if you are truly arcing the distance or if your drawing the arc across.
```
```
When running, it may quench before it reaches the next electrode in which case may appear like a static gap. I think if this is the case, the next electrode may not fire and then the following electrode has a very high voltage which conducts, this time drawing the arc all the way to the next electrode. And then we start over again. Sort of a very erratic running situation at that point.
```
Throwing some food for thought out there.
Take care,
Bart

bamacoiler@xxxxxxxxx wrote:
```
I think he means that when he goes past 75-80% on the variac the voltage finds a better path to conduct and acts as a static gap instead of taking the path that he designed.
```
Scott,
```
If your only using stationary electrodes on one side why have the copper ring?
```Garry Neeley
---------- Forwarded message ----------
From: "Lau, Gary" <Gary.Lau@xxxxxx>
Date: Oct 23, 2008 2:51pm
Subject: RE: [TCML] Rotory STATIC Gap
To: Tesla Coil Mailing List <tesla@xxxxxxxxxx>

```
```Hi Scot,

```
If you're seeing the spark gap jump anything remotely like 2.2 inches,
your coil components (cap and NST?) are not long for this world. That length indicates that the cap is charging to a MUCH too high voltage. Any rotary gap, sync or not, needs to have a properly spaced static gap in parallel with it, so that it fires before the voltage gets out of hand and things start going poof.
```

```
I'm having trouble visualizing your setup, so it would help a huge amount
```if you could post some photos.
```
```

```
Also, please be consistent in the use of the word "static". Your RSG has
rotating electrodes, and it has stationary electrodes. When you say that it has static electrodes, or operating in static mode, I'm not sure what you're referring to.
```

Regards, Gary Lau

MA, USA

> -----Original Message-----

> From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On

> Behalf Of bunnykiller

> Sent: Thursday, October 23, 2008 2:09 PM

> To: Tesla Coil Mailing List

> Subject: [TCML] Rotory STATIC Gap

>

> Hey All....

>

> I was looking at my spark gap ( SRSG) and noticed that the timing must

> have been off or the primary circuit voltage had jumped up quite a bit

> and started arcing before the electrodes were in position. The gap is

> designed with 4 flying electrodes and 2 static, since I couldnt place

```
> the statics on each sides of the disc, I had to put them on one side of
```

```
> the disc ( away from the motor). To achieve conduction, I had to place a
```

> copper ring around the periphery of the disc to conduct from one

```
> electrode to the next. (This was done to keep the stationary electrodes
```

> from arcing to the motor.)

>

> This configuration allowed the primary circuit to charge to voltages (

> well as far as the distance from the stationary gap distance was from

```
> the copper ring ( 2.2" total gap width)) which would then jump the 2.2"
```

> length to conduct. As the electrodes would proceed into the stationary

> region, it would ( im supposing now) lower the gap voltage for

> conduction and eventually quench.

>

```
> So in effect, the gap was firing in "static" mode and then finished off
```

> in rotory mode. Guess I need to get rid of the copper ring to have a

> true SRSG.... ;)

>

> At lower input voltages to the piggie, the gap works fine ( as its

```
> supposed to) but once past 75-80% on the variac, the "static" mode
```appears.
```
```

>

> Need to design a better SRSG that can fend off 40KV+ and not attack my

> motor....

>

> Scot D

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