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Re: Grounding Question



Original poster: Dave Lewis <hvdave-at-earthlink-dot-net> 

Hi Gary,

Nice article you wrote there.

My personal preference is to stick with the "backwards" filter
connection... except I tie the filter case ground to the 120Vac line
ground, not the RF ground as you've shown.  This way the "Y" caps aren't
getting hit with direct RF spikes since the CM inductors are providing
insertion Z.  Y caps also shunt some of the RF to the line ground rather
than letting it find its way back on the hot and neutral wires.

Also I'd add that its not a bad idea to put an extra CM inductor in
series with the EMI filter to the NST power input.  I wound mine with
about 10 turn of #12 on a high perm silicon steel torroid core.  That
futher decouples the RF ground from the line ground.

Dave Lewis




Tesla list wrote:
 >
 > Original poster: "Lau, Gary" <gary.lau-at-hp-dot-com>
 >
 > Yes, this is a confusing topic.  Basically, you want everything downstream
 > from the variac tied to RF ground.  This includes the NST case, safety
 > gaps, RC filter ground, strike rail, and secondary base.  The variac case
 > (anything that one might touch)  should be tied to mains ground, for safety.
 >
 > When the NST case is tied to RF ground, it's a good idea to use an EMI
 > filter between the mains and the NST primary, but the Line/Load connections
 > and choice of ground connections here is even more confusing.  Please see
 > what I've written on this topic on my web site at
 > http://www.laushaus-dot-com/tesla/emifilter.htm
 >
 > The strike rail must NOT form a continuous loop; there must be a small gap
 > between the two ends.  Otherwise this will act as a shorted turn on a
 > transformer and cause much power to be wasted.
 >
 > Gary Lau
 > MA, USA
 >
 > Original poster: "EMMETT SECREST" <secrest2032-at-msn-dot-com>
 >
 > Hello All,
 > I am confused on the proper grounding for my first TC.  If someone would be
 > so kind as to clear it up for me I would appreciate the help. I know the
 > secondary RF ground should be a separate ground. Where I am confused is the
 > ground for the safety gap on the Terry Filter.
 > 1.Does the Safety gap ground tie in with the secondary RF ground?
 >
 > 2.Also I have a ground to the NST from the 120VAC supply. Should this
 > ground also attach to the Safety Gap ground or should the supply ground
 > stop at the NST housing.
 >
 > I apoligize for asking what is I'm sure a very basic question of such a
 > learned group of people. But if you don't ask you don't learn.
 >
 > I considered not even running a ground to the NST from the supply AC and
 > attaching the NSTchassis, RF,strike rail and Safety Gap grounds all
 > together. MY thinking was that that would protect everything in case of a
 > primary strike from the secondary.
 >
 > 3. Does it matter if the strike rail is a continuos piece of copper tubing?
 > I spliced the ends together to add better support to the copper tubing.
 >
 > Thanks in advance to all who reply
 >
 > Emmett Secrest