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Re: Safety gap - setting
Original poster: "Gerry Reynolds" <gerryreynolds@xxxxxxxxxxxxx>
Hi Dennis,
Your method of setting the safety gap is correct if your variac puts
out 130V max. What kind of main spark gap are you using and how is
it set. Normally a static main gap (in parallel with the safety gap)
is set similar to the safety gap but to barely just fire at maximum
variac setting. If the main gap is set correctly, it should fire
before the safety gap does. When I use to have static gaps, I would
increase the main gap until I would occasionally have a safety gap
firing. Your main gap may be set too wide (assuming you are using a
static gap) and allowing the safety gap to fire. Also, what is the
value of your Cp and size of the NST?? Many in this group recommend
a Cp value that is around 1.5-1.6*Cres where Cres is the value of Cp
that is line resonant with the NST. If you describe your power
source, we can help with the Cres value.
I would not increase the safety gap further than what you originally
set it for. I would also recommend a gradual power up. This is just
a good practice incase something ever goes wrong. The sudden
application of power can cause initial transients that can push the
normal voltage higher until something breaks down. Instead of
opening the safety gap to allow sudden power up, try to reduce the
main gap a notch.
Gerry R.
----- Original Message ----- From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Sunday, December 03, 2006 9:54 AM
Subject: Safety gap - setting
Original poster: otmaskin5@xxxxxxx
I just finished rebuilding & resetting my safety gap, but I'm not
sure I got it right. Basically I set the gap so it just barely
wouldn't fire at full 130v variac setting. I tested the setting by
dialing the variac from 0v to 130v pretty much the way I would do it
if I were actually starting up the tesla coil.
My question is this. When I already had the variac set at 130v &
then hit the "on" switch, the safety gap would fire. This abrupt
powering up would fire the gap at settings that would not fire when
I gradually dialed up the voltage to max. To get the gap so it
wouldn't fire when I powered it up abruptly, it required a much wider setting.
Which of the 2 methods to test gap setting is correct - abrupt full
power or gradual dial up? Thx for any suggestions. Dennis Hopkinton MA