Re: [TCML] Terry Filter, Saftey Gap Distance?

[<ConorPerry@xxxxxxxxxxx>]

Thank you for your info.  I'm curious how you came up with your 11/64" 
(0.172") gap distance?  How you mention the atmospheric effects I wonder if 
it's more from empirical data than by calculations.  Are you setting the 
gaps just larger than they will fire without the primary?

When I initially calculated for mine I used the 3,000,000 Volts/Meter as the 
dielectric of air (
76,200 Volts/Inch).  My 12/100 NST with a Variac is guessed to have an 
output of 14kV.  So I set my gaps just above that voltage at around 8kV per 
side, which is a distance of 0.11".

Then I run your numbers with the same math, but with a 15kV NST on a Variac 
to make 17.5kV.  Your gap of 0.172 calculates to 13kV per side, and 26kV 
total.

So am I set too conservative, or are you too high?  Do your safety gaps ever 
fire?  Maybe my assumption of using the 3,000,000 V/m is unfounded (since 
that's "standard air" at 1atm.)

CP8071

----- Original Message ----- 
From: "Lau, Gary" <Gary.Lau@xxxxxx>
To: "Tesla Coil Mailing List" <tesla@xxxxxxxxxx>
Sent: Saturday, June 14, 2008 10:19 AM
Subject: RE: [TCML] Terry Filter, Saftey Gap Distance?


With my 15/60 NST operating from a 140V Variac, each of the two gaps measure 
11/64".  But please understand that your setting is likely to be different. 
The shape and diameter of the electrodes, and local altitude, maybe even air 
pressure, will all affect the setting.  Safety gaps should me built so they 
are easy to set the gap distances.

To Nicholas asking about safety gap electrodes, many including myself use 
brass drawer knobs.  You can use 3 of them, although I happened to have a 
brass cylinder that looked nice for the middle electrode - see bottom of 
http://www.laushaus.com/tesla/protection.htm

Regards, Gary Lau
MA,. USA

-----Original Message-----
From: tesla-bounces@xxxxxxxxxx [mailto:tesla-bounces@xxxxxxxxxx] On Behalf 
Of ConorPerry@xxxxxxxxxxx
Sent: Friday, June 13, 2008 6:12 PM
To: tesla@xxxxxxxxxx
Subject: [TCML] Terry Filter, Saftey Gap Distance?

As I've increased power my safety gaps on the Terry filter have started 
firing, sometimes very often.  I've seen the original schematic and several 
peoples builds, but never seen any distance shown for what the gaps should 
be.  I'd guess that they'd change depending on the transformer voltage, but 
what gaps for the standard NST voltages?

CP8071
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