Re: 2 questions: SRSG & LTR Caps

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "marc metlicka by way of Terry Fritz <twftesla-at-qwest-dot-net>" <mystuffs-at-orwell-dot-net>

Matt,
It is a very simple situation that happens with this phase adjuster. As
i mentioned to John in the beginning, the perfect system would be a
variable cap directly connected to the shaft of the variable inductor,
the cap would begin to travel after the inductor hit it's bottom limit.
 I think you could match values by checking the power factor of the
srsg  motor at the loaded condition, this would give you the base line
were the sync motor needs to run across the board, Then Pfc. this to
make the motor look like a resistive load at half travel of the
inductor. Also the reason some only see up to 45 degrees of phase shift
is that the inductance of the hv transformer itself is "lagging" the
current.
This is were the "trial and error" for most coilers come into play. 
Then knowing the current lead that your inductor provides across it's
travel, you could set a variable cap that would be initiated from the
center inductor travel downward. This is how i gained a full 180 degree
of phase difference for the first setup i made.
If only 90 degrees of phase drift is sought, then one just has to set a
Pfc. value for the lowest setting and then use the inductor as a
"lagging" unit.
Or one could use a center travel, apparent resistive Pfc. and allow the
cap to "lead" the current to the voltage.
I hope this explains how the phase adjuster works?, the natural
inductance in our modified motors is already lagging the current, a Pfc.
cap value brings that back. With the addition of the variac as an
inductor before the motor, this gives an additional "lagging" factor up
until 90 degrees (it cannot go over 90 degrees for obvious reasons), so
with this variable inductor only, there will be a max lag of the motors
electrodes compared to "sync" line that fires the tank (+ - due to the
inductance of the tank transformer), by 90. But with an adjustable cap
taking over the system can go from 90 degrees lagging to 90 degrees
leading the line current. it is this current to voltage factor that
fires at desired alignment time for rotaries, it REALLY governs when a
static gap fires.
This adjuster has been in effect for over a year now and i have waited
for someone to anyone to exactly explain "how it works"?

Now as for me, I have seen no benefit to a full 180 degrees of phase
angle adjustment! one can only twist the knob from completely out -
right on and then right back to out. so 90 degrees to 120 degrees
adjustment will allow you to "tune in" a setup. (120 degrees is a good
factor to shoot for)

But then again,
 The sync. triggered spark gap does this better, cheaper and simpler to
build. It is always within tuning parameters and the option is always
there to raise the break rates. Hard to do with a rotary without adding
electrodes. Thus my early statements saying that rotaries are
"outdated".
Take care,
marc

Tesla list wrote:
> 
> Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>"
<Mddeming-at-aol-dot-com>
> 
> Tried firing up a SRSG with phase control tonight with dismal results. I
> suspect the components are of incompatible size. No significant change in
> phase(<5deg), even using modified strobe (per Terry) to check visually.
> 
> 1.     Salient pole motor 1/7 HP 3600 RPM
> 2.     6"  2-electrode disk
> 3.     3.5A 120 V Variac
> 4.     15uf -at-660V Cap
> 5.     47K-ohm resister across cap
> 6.     5A fuse
> While I have lots of caps and resistors, but don't have a feel for
direction or
> order of magnitude of change needed. Anyone with experience please advise.
> 
> For LTR Caps with 15 kV NSTs is the rule of thumb of 0.5nF per mA fairly
linear
> for 30-300 mA? i.e. 15nF -at-30 mA, 30 nF -at- 60 mA, etc.
> 
> Thanks,
> Matt D.
> G3-1085