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LAN_403

LD LANGER

Sat Sept 10 2011, 07:53PM

Registered Member #3824 Joined: Sun Apr 10 2011, 08:29PM
Location: Edmonton, Alberta, Canada
Posts: 54

Hello, I am about to run my DC Tesla coil indoors in my office and I am wondering if there is any implication to leaving the secondary ground floating? I have no means for a separate RF ground, so will leaving it floating be dangerous to the power feeding the coil (ie. I have no filter and am wondering if this will destroy my office server and get me fired)?

DC Resonant coil w/ 5 MOT's in series w/ primary shorted for charging inductor, 17uF tank, 2 MOT's w/ DC cap for charging transformer, really shotty rotary.

Thanks for the time.

Dr. ISOTOP

Sat Sept 10 2011, 08:20PM

Registered Member #2919 Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652

17 MICROFARAD tank? You sure you don't mean nF?
And you'll want to ground secondary ground to something.

LD LANGER

Sat Sept 10 2011, 08:38PM

Registered Member #3824 Joined: Sun Apr 10 2011, 08:29PM
Location: Edmonton, Alberta, Canada
Posts: 54

yeah sorry 17.5 nano, my mistake! Yes, would it be appropriate to just use a steel plate? I just don't want any RF leaking back into the circuit

magnet18

Sat Sept 10 2011, 08:38PM

Registered Member #3766 Joined: Sun Mar 20 2011, 05:39AM
Location:

Posts: 624

If you don't ground the secondary it can easily break out of the bottom of the coil and strike the primary

Put an rf choke on a line and that might block most of the bad stuff, allowing you to connect it to the mains ground, but don't take my word for it.

running it outside would be a much better idea.

Herr Zapp

Sat Sept 10 2011, 09:47PM

Registered Member #480 Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644

LDL -

Is it absolutely necessary to run the coil in your office? A small "desktop" coil is less risky, but a dual-MOT powered coil has the potential to cause havoc.

Regardless, do NOT try to run that coil without "grounding" the secondary to either a solid earth ground or a large (minimum 4' X 4') counterpoise directly under the coil. A counterpoise is just a local "isolated" gound plane, of sheet-metal, heavy aluminum foil, etc.

With a coil of that input power level, I'd be really concerned about having robust filtering on your AC input line. What type of electronic equipment is in your office? I'd unplug every piece of electronic equipment within a 25' radius of the coil, and disconnect all cables connected to that equipment to reduce the chances of having RF energy from the coil couple into the equipment through the cabling.

Herr Zapp

LD LANGER

Mon Sept 12 2011, 05:30PM

Registered Member #3824 Joined: Sun Apr 10 2011, 08:29PM
Location: Edmonton, Alberta, Canada
Posts: 54

Herr Zapp wrote ...

LDL -

Is it absolutely necessary to run the coil in your office? A small "desktop" coil is less risky, but a dual-MOT powered coil has the potential to cause havoc.

Regardless, do NOT try to run that coil without "grounding" the secondary to either a solid earth ground or a large (minimum 4' X 4') counterpoise directly under the coil. A counterpoise is just a local "isolated" gound plane, of sheet-metal, heavy aluminum foil, etc.

With a coil of that input power level, I'd be really concerned about having robust filtering on your AC input line. What type of electronic equipment is in your office? I'd unplug every piece of electronic equipment within a 25' radius of the coil, and disconnect all cables connected to that equipment to reduce the chances of having RF energy from the coil couple into the equipment through the cabling.

Herr Zapp

Yes, I'm setting the coil up for display in the office, so it will be run indoors. The main office server is running off the same panel as this, so that could be an issue. The reason why I think its okay would be that as this is a DC resonant coil, I have a VERY large charging inductor that will not allow any RF current back. I will have to use a counterpoise below the coil that I will lay on a layer of bituthane to isolate it.
Should I be worried about this?

Thanks,
Daniel

Herr Zapp

Mon Sept 12 2011, 06:53PM

Registered Member #480 Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644

LDL -

"Should I be worried about this?"

Worried about the bituthane?

Or worried about taking out the server?

I think running ANY Tesla coil on the same branch circuit as an office server is risky, at best. And, injecting RF noise into the AC line may not be the most dangerous path for coupling energy into your office LAN. Aren't there 100's of feet of LAN cable spiderwebbing the office?

Do your IT people know about this? What are the consequences of crashing the server, or wiping out the RAID array?

I've only had one experience with a TC damaging nearby electronics devices, but it wasn't pretty. Many others have reported unpleasant experiences with toasted modems, televisions, stereo systems, test equipment, garage door openers, etc.

Herr Zapp

LD LANGER

Tue Sept 13 2011, 02:03AM

Registered Member #3824 Joined: Sun Apr 10 2011, 08:29PM
Location: Edmonton, Alberta, Canada
Posts: 54

Herr Zapp wrote ...

LDL -

"Should I be worried about this?"

Worried about the bituthane?

Or worried about taking out the server?

I think running ANY Tesla coil on the same branch circuit as an office server is risky, at best. And, injecting RF noise into the AC line may not be the most dangerous path for coupling energy into your office LAN. Aren't there 100's of feet of LAN cable spiderwebbing the office?

Do your IT people know about this? What are the consequences of crashing the server, or wiping out the RAID array?

I've only had one experience with a TC damaging nearby electronics devices, but it wasn't pretty. Many others have reported unpleasant experiences with toasted modems, televisions, stereo systems, test equipment, garage door openers, etc.

Herr Zapp

Well the business owner knows about it, actually he asked me to bring it in. So here's the thing, will there be any danger to the *extremely* valuable server if I were to run it outdoors one the same panel (but not same branch circuit) considering what I have previously said about the size of the charging inductor? If not, I would think installing a simple faraday cage would be a good decision, no?

Thanks,

Daniel

Herr Zapp

Tue Sept 13 2011, 02:49AM

Registered Member #480 Joined: Thu Jul 06 2006, 07:08PM
Location: North America
Posts: 644

LDL -

Why not rent a small portable generator (3-5 KW), and run the coil outside (like in a corner of the parking lot), with a dedicated ground rod? This would pose a minimal (but not absolutely non existent) risk to the server or other electronics in the office.

This way you could honestly claim to have taken "reasonable" precautions against disrupting your office LAN.

Just to help put this all into perspective, what is the typical output of your coil, expressed as streamer length?

Herr Zapp

LD LANGER

Tue Sept 13 2011, 03:07AM

Registered Member #3824 Joined: Sun Apr 10 2011, 08:29PM
Location: Edmonton, Alberta, Canada
Posts: 54

I have yet to test it, out of safety reasons for my office. It is a DC resonant charging coil powered by two MOT's in series. I have a 3uF cap in parallel to reduce ripple, 5 MOT secondaries in series, a 30kV de-qing diode, 17nF tank and a crappy rotary gap.

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