Re: types of "quenching"

Subject:  Re: types of "quenching"
  Date:   Mon, 21 Apr 1997 14:51:55 -0400 (EDT)
  From:   FutureT-at-aol-dot-com
    To:   tesla-at-pupman-dot-com

> I bought a vacuum fan from American Science Surplus.  It has an AC/DC
> motor.  The motor RPM's can be adjusted using a
> variac.  I have found by increasing the fan motor RPM's the secondary
> coil output increases also.  The secondary coil output
> increase up to a point where the Tesla Coil peaks out to maximum
> secondary coil spark output.  If the fan motor RPM is
> increased beyond this point the spark output of the secondary coil
> decreases.  Too much air flow is over quenching the spark
> gap.
>Big Snip
> Gary Weaver

Gary, All,

Glad to see you're doing these types of experiments.  There are actually
different kinds of "quenching" that occur in TC operation.  One kind
mostly with static gaps, the other kind occurs with every kind of gap,
static, rotary, etc.  

It would probably be better if two different terms were used to describe
these two quite different kinds of "quenching".  I put quenching in
because one of these quenching types is not really quenching at all in
strictest sense, but can be considered to be quenching is a looser

I'll call these type 1 quenching, and type 2 "quenching".  I'll define
type 1
quenching as "the ability of the gap to stop firing, once it starts". 
define type 2 quenching as "the ability of the gap to start firing at a
certain voltage".  Actually type 2 quenching is not quenching at all,
actually a delay in firing.  In your experiment, you are seeing first
benefits of type 1 quenching, and then later, as the spark decreases,
hindrance caused by type 2 quenching. 

In a static gap system, if the type 1 quenching ability is really poor,
spark will not be able to break easily once it starts, and will continue
fire as a "power arc", thus preventing the repetitive charging of the
 The result is that fewer cap charge/ discharge cycles will occur per
60Hz AC
half cycle, less power will be processed through the system, and the
spark will be weak.  Perhaps even if the type 1 quenching is not poor
to cause actual power arcing, it may still reduce the power output, if
quench occurs on a "late-occuring" notch, such as the 4th, or 5th

As more air is blown across the gaps, it will become harder and harder
the gaps to fire at a given voltage level, or point, along the AC sine
(this is type 2 quenching).  This will delay the firing of the gaps, and
also result in fewer gap firings per 60Hz AC half cycle, so the result
again be a shorter spark, but for a very different reason than in type 1
quenching problems.   The type 2 quenching can be considered to be a
form of
quenching if "quenching" is thought of as something that PREVENTS gap

The recent quench work I've been doing addresses only type 1 quench

Happy and "quenchy" coiling,

John Freau