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Re: [TCML] Best Spark Gap for NSTs?



The answer is not simple or direct.  There are advantages and
disadvantages for sync or non-sync.  


Did you happen to try
feeding the motor with 140V from a step up type variac?
Often this will keep it in sync.  If you created flats on
the rotor that are at least 1/4 the width of the full rotor diameter,
that is enough metal to remove.  Some small motors
are very wimpy and don't work well such as small
shaded pole fan motors.  And of course you should
have 4 flats on your motor.  


Yes the preferred break rate has a lot to do with it.
Sync operation is most beneficial at low break rate
of 120 bps.  However it's absolutely necessary to
use a large enough capacitor to take advantage of
this.  Back in the "day", a lot of people were installing
a sync gap onto their TC and getting worse results
because they were using a small capacitor with
a static gap previously.  They left the small 
capacitor in place and therefore saw a reduction
in spark length when they installed the sync rotary
gap.  


For anything over 120 bps, sync doesn't really
help, you might as well use non-sync or a static
gap.  Gary Lau posted some information about
the best capacitor sizes for sync or non-sync, etc,
in the past and I guess this is at his website.  Also
JavaTC might give some information about the
best capacitor values for sync or non-sync, for
NST powered coils.


120 bps sparks will not be quite as bright as
higher breakrate sparks.  Also they tend not
to create the kind of long tendrils that can
form at higher breakrates.  Certain coils
tend to show these long thick tendril
type sparks.


John  



-----Original Message-----
From: Daniel Kunkel <dankunkel@xxxxxxxxx>
To: Tesla list <tesla@xxxxxxxxxx>
Sent: Sun, Feb 25, 2018 9:45 am
Subject: [TCML] Best Spark Gap for NSTs?

I modified a 1725 rpm motor to run in salient pole operation years ago. It
will seek and then lock into phase and then break out again. I think I
recall reading that if you don't remove enough rotor material it will seek.
If you remove too much it will over heat.

So before to I take this back to machining, is it even worth it? What is
the best gap for NSTs? Is SRSG is the answer what is the preferred break
rate?

~Dan
To synch or not to synch
Kansas City area
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