Re: blowing fuses: troubles with a new system

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

Original poster: "Crow Leader by way of Terry Fritz <teslalist-at-qwest-dot-net>" <tesla-at-lists.symmetric-dot-net>

----- Original Message -----
From: "Tesla list" <tesla-at-pupman-dot-com>
To: <tesla-at-pupman-dot-com>
Sent: Thursday, June 26, 2003 10:18 PM
Subject: blowing fuses: troubles with a new system


 > Original poster: "Steven Ward by way of Terry Fritz <teslalist-at-qwest-dot-net>"
<srward16-at-hotmail-dot-com>
 >
 > HI everyone,
 >
 > its been awhile since ive built a spark gap coil (ive been doing VTTC and
 > SSTC work), so i put a new one together.  But im having problems in that
 > the coil appears to have terrible power factor!  Here are the specs:
 >
 > 15/120NST (was a France 15/60, but i removed shunts (left 12 leaves in
each
 > packet for a rough estimate of 120ma))
 >
 > 238uf of PFC (its too small, maybe my problem???)

238uF -at- 120 volts and 60Hz = an impedance of 11.15 Ohms, or 10.75A of
reactive current. That sounds like half of what your fuse is even rated. Is
your power factor really this bad, or is it saturating? Have you tried to
measure it, or looked at it on a scope? How did your transformer behave
before you modified it?

If it was really as easy as removing shunts and getting more power, France
would have done this at the factory and saved a bundle by making half size
transformers with the same power rating.

KEN

 > .045uf MMC (also a bit too small for the system)
 >
 > 120BPS sync gap
 >
 > 7.5" ID 23"OD flat primary, 14 turns 1/4" tube, tapped at 11.
 >
 > 6.3"OD x 24" winding of 24awg magnet wire for a secondary
 >
 > 4.5"x30" toroid.
 >
 > So far, ive been using the phase controller that John Freau has on his
site
 > (variable inductance and an extra capacitor with a small sync motor).  The
 > SRSG is similar to a Terry Blake setup, it uses a 7" tungsten rod with 4
 > electrodes spaced around it.  Would be similar to an 8" SRSG disc.
 >
 > Ok, so when i test with power, i can get up to about 50% input on the
 > variac, then the 20A fuse blows!  The coil puts out 3-4 feet of sparks at
 > that point.  Ive noticed that, as i turn up the power, i need to reset the
 > phase controller (lower the inductance) to keep the coil happy (otherwise
 > the safety fires, and the coil looses the synchronous tone).  Though, im
 > sure the motor is still spinning sync, since its fine at a lower
 > level.  Ok, so i get to about 50% and adjust the RSG for maximum output
 > (which is JUST before it starts to flash on the safety gap) and
 > watch.  Then the fuse blows.  It seems that, when i turn up the power
 > without adusting the phase controller, the SRSG pulses or surges, but i
 > dont know why.  Though John Freau told me this is common ( the need to
 > reset the phasing at higher powers).  I notice that if i adjust the
phasing
 > in the other direction, the sparks get shorter, and there is a wide area
of
 > settings that will work fine (and this does not seem to blow the fuse),
but
 > the spark output is MUCH weaker :o(  So does anyone have some advice for
me
 > besides get a bigger fuse??  (by the way, its it ever ok to put a 30A fuse
 > inplace of a 20 ;) ).
 > Im actually going to hire my uncle (electrician) to wire me my own power
 > box off of the mains with a 240V and high current 120V line, but that wont
 > be for a while.  So i need answers now!
 >
 > here are my thoughts on a possible solution. 1) put all of the shunts back
 > into the NST and run it at 60ma (though im sure the setup will pull much
 > more power out of it).  Im not sure how effective it would be with a
.045uf
 > cap.  I could run .030 uf i guess, but i want big sparks!  2) add more
PFC?
 > I think i really need like 450uf or something like that for this amount of
 > power. 3) whatever anyone else could suggest!!
 >
 > Thank you all in advance.
 >
 > Steve Ward.
 >
 >
 >