Rotary gap grounding

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

Original poster: "by way of Terry Fritz <twftesla-at-qwest-dot-net>" <Esondrmn-at-aol-dot-com>


We have discussed this in the past, but I do not recall what the popular
opinion was.  For those with rotary gaps, do you ground the motor case?  If
so, to what ground?  The items that are likely to get hit with a strike from
the toroid, we usually tie to the main RF ground.  This doesn't seem like a
real good choice for the motor case ground since the RF ground is often at
least several hundred volts above actual ground.  I base this idea on the
observation that you can draw sparks off the main RF ground wire when the
coil is running.  I doubt the motor case / field winding set up was designed
with more than a few hundred volts insulation in mind.  My existing gap motor

is mounted in a wooden box and is under the coil and out of the way.  That
motor case is floating.  The new rotary I am working on will be in a more
likely area to get hit with strikes.  I planned to also build a wooden box to

enclose it and will add a metal strike shield on top if necessary - but am
still undecided as to what to do with the motor case.

Ed Sonderman