Re: [TCML] Alternative RSG Motor and shielding

[Mark X2 <susax2@xxxxxxxxx>]

Had to dig into the archives, but when it comes to TC grounding,
I find this thread by Richard Quick very valuable:
http://www.pupman.com/listarchives/1995/november/msg00132.html

quote:

"You build or find a heavy ground and you ground your coil system
to it. The connections made to this RF ground are as follows:
SECONDARY COIL, SAFETY GAP, STEP UP XFRMR CORE, BYPASS CAPACITORS
(if using a center tap grnd xfrmr), SPARK GAP MOTOR HOUSINGS,
SPARK SHIELDS, AND ANY OBJECT SUBJECT TO BE STRUCK WITH DISCHARGE

I don't usually use my caps lock, but this is important. This
technique prevents RFI complaints, and will save valuable
electronic equipment in your area from destruction. It may save
you from the last shock of your life.

You ground your variac housing to your neutral wire. All other
coil controls, relay housings, control xfrmr cores, line RFI
filters (run backwards) are grounded to the variac housing. Strap
is taken from the variac housing to a well grounded water pipe.
This protects the coil operator and the control circuits from
kickback that may come down the line from the step up xfrmr.

Two 60 cycle cables are run from the variac, through reversed
line filters, out to the step up xfrmr. No ground connection is
made anywhere between the 60 cycle cabinet ground and the RF
system ground. Hot wires only are given to the primary of the
step up xfrmr, as well as any gap motors or other utility for the
coil tank circuit.

This is called the "two ground system" and it is highly recom-
mended. The idea of the two ground system is to send all of the
RF to a dedicated ground, and prevent bleedover into your house
wiring, control cabinet and/or water pipe. It also protects the
operator with two low potential grounds from the lethal possi-
bilities of a coil misfire or similar "incident"."





2013/8/29 Yurtle Turtle <yurtle_t@xxxxxxxxx>

> I have done so, and managed to kill 2 VFDs. I finally found evidence that
> my electrodes were arcing to the motor base, so that's easy to fix.
>
> Like you, I have a question on the best way to not kill my last remaining
> VFD. I've read about protecting the three phases, but don't have the specs
> handy.
>
> I'm currently only running three wires to the motor, and letting the motor
> housing float.
>
>
>
>
> ________________________________
>  From: Greg Peters <greg.j.peters@xxxxxxxxx>
> To: tesla@xxxxxxxxxx
> Sent: Wednesday, August 28, 2013 11:31 PM
> Subject: [TCML] Alternative RSG Motor and shielding
>
>
> Hi All,
>
> I am in the process of building an ARSG for my new DC coil. I have already
> had an FR4 12" disc CNC machined and will be using 10mm flying electrodes.
> It's looking good!
>
> I was originally going to use a DC or universal motor but was able to
> obtain a 1HP 3-Phase motor with a single phase to 3 phase inverter for less
> than half the price.
>
> Essentially the inverter allows me to run the 3 phase motor from a single
> phase with variable speed control from 0 to 6000RPM. It works very nicely.
>
> Anyway, I suddenly have concerns that I might have trouble getting this
> arrangement to work in the vicinity of the TC due to RFI.
>
> I was thinking that if I run the inverter in a shielded box, ground the
> motor housing, use shielded cable to the motor and an EMI filter on the
> inverter supply then I should be OK. Does anyone have any thoughts on this,
> before I go spending money on getting a coupling machined to mate the disc
> to the motor? If it's a lost cause I will just find a new type of motor,
> but I think I should be able to get it to work.
>
> If it does work, it's actually a very nice setup. The motor is industrial
> with a cast housing, big bearings, solid mounting and a thick 19mm shaft
> with keyway. The inverter allows full speed control and even reversing with
> the twist of a knob!
>
> Anyone tried using such a motor and inverter setup?
>
> Advice is appreciated!
>
> Greg.
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