Re: Overheating MOT - dual 833A VTTC

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

Original poster: "by way of Terry Fritz <teslalist-at-qwest-dot-net>" <dhmccauley-at-spacecatlighting-dot-com>



Thanks John.
Yes, I did conclude that this evening by removing the MOT and placing it far
away.  The MOT only gets smoking hot after long periods of run time (more
than 3 minutes) and when running at 100% input voltage and very high duty
cycles - high PRF's using the stacatto controller.  Power levels at this
condition i was measuring to be 3kW + + + + No wonder that thing was getting
smoking hot.
This evening i got my VTTC to consistently hit the 28" mark.  I was really
pscyched.  This was at 80% input voltage.  Any additional increase in input
voltage caused the swordlike appearance of the streamers to decrease and
therefore decreasing overall length.  BTW, I'm currently using (5) MO
capacitors for a total of about 4uF.  I'll be posting pictures later this
evening once I download them off my camera.

Dan



 > >I'm having some problems regarding my MOT (microwave oven transformer)
 > >overheating with my dual 833A.  The size of the MOT is about 5" x 5" x 5"
so
 > >its a fairly large transformer, and actually its heats up considerably
even
 > >during lighter loading.  Do you think maybe proximity is a problem?  The
 > >transformer is approximately 12" away from primary and underneath by
about
 > >6" inches on a separate level.
 >
 >
 > Dan,
 >
 > If you have at least 12" spacing between the MOT and the primary,
 > that's plenty of distance and the primary should not cause MOT RF
 > heating.  Most likely it's the current draw that's heating the MOT.
 > My 24" spark VTTC draws 2400 watts, and the amount of MOT heating
 > is acceptable.  I like to keep the run times somewhat limited to
 > prevent MOT overheating.  I use only two MO caps, so that may be
 > helping to reduce the current draw.  An MOT is somewhat marginal
 > in this application but I selected it for compactness, low weight,
 > availability, cost, etc.
 >
 > John
 >
 >
 >
 >
 >