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Safety and hazards of voltages

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Andy

Mon Apr 08 2013, 03:02AM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
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Posts: 874

Hi, What would be the hazards of 100kv,200kv,300kv,400kv.....How would I setup the lab to minmise this.

Thanks

Houdini0118

Mon Apr 08 2013, 04:05AM

Registered Member #8558 Joined: Thu Dec 06 2012, 11:38PM
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Posts: 57

Death and explosions come to mind.

Andy

Mon Apr 08 2013, 05:22AM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
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What materials for the work bench. For light fixture do I need to keep the arc length *2 away.
I've reached 100kv And i'm still alive :(, but wood has surface arcs

Sigurthr

Mon Apr 08 2013, 07:41AM

Registered Member #4463 Joined: Wed Apr 18 2012, 08:08AM
Location: MI's Upper Peninsula
Posts: 597

Wood becomes conductive as frequency increases, so if your HV is also HF you need to switch to something other than wood for insulation. Delrin, PVC, acryllic, porcelain, glass, and polypropylene are all excellent insulators at higher frequencies.

The general rule of thumb is for every 1mm you need 1kV to break down the air in between two rounded surfaces. Sharp surfaces have higher charge densities and require lower voltages to break down across the same distance.

So for a HV lab you need adequate and ample grounding, adequate and ample insulators, and adequate and ample space between you, anyone else, and anything sensitive and the source of the HV. Safety power disconnects and bleeder resistors across any capacitive element are not optional.

The most important aspect is maintaining absolute rigidity of safety precautions and standards. Never touch ANYTHING without checking over and over again that all power is off and everything is discharged.

Antonio

Mon Apr 08 2013, 02:11PM

Registered Member #834 Joined: Tue Jun 12 2007, 10:57PM
Location: Brazil
Posts: 644

Voltage is not dangerous. Energy is. You can safely play with a 200 kV Van de Graaff generator, but if you draw a spark from a 10 kV power line you die. Note that most of the 100's of kV devices mentioned in the Internet, including this forum, don't actually go above 25 kV, that is easy to "contain" without much care. At 50 kV you have corona everywhere, and all the installation must have rounded corners and ends, and long insulators. At 100 kV these precautions must be more than doubled. Use at least 1 cm of radius for each 30 kV for spheres and rounded ends. Less can be used for straight connections. Basic safety measures are, obviously, never touch a high-voltage low-impedance device while it is working, and specially never touch it with both hands. For insulation, never use wood, paper, or similar materials (although they may work if saturated with a good insulator as paraffin or other waxes).

Patrick

Mon Apr 08 2013, 05:31PM

Registered Member #2431 Joined: Tue Oct 13 2009, 09:47PM
Location: Chico, CA. USA
Posts: 5639

Houdini0118 wrote ...

Death and explosions come to mind.

Yes, I too imagine these "issues"

First, and above all, Distance is the best defense against any human safety and health threat. (if a nuclear weapon goes off on the moon, no big deal. If a hand grenade is thrown into a locked phone booth, your screwed.)

then, and much less effective, there is armor, shielding and insulation.

finally, theres a bunch of fiber optic and other safety features that can be implemented.

HV Enthusiast

Mon Apr 08 2013, 05:51PM

Registered Member #15 Joined: Thu Feb 02 2006, 01:11PM
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What type of experiments would you be conducting at those voltages?

Andy

Mon Apr 08 2013, 06:36PM

Registered Member #4266 Joined: Fri Dec 16 2011, 03:15AM
Location:
Posts: 874

Note that most of the 100's of kV devices mentioned in the Internet, including this forum, don't actually go above 25 kV, that is easy to "contain" without much care. At 50 kV you have corona everywhere, and all the installation must have rounded corners and ends, and long insulators. At 100 kV these precautions must be more than doubled. Use at least 1 cm of radius for each 30 kV for spheres and rounded ends.

How would you go about stopping corona from the wires that interconnect things

What type of experiments would you be conducting at those voltages?

Trying to experiment with arcs and plasma. Was planning on making a voltage doubler with 20 stages with 15Kv input to get a longer distance at the moment its only 4cm.

Wood becomes conductive as frequency increases, so if your HV is also HF you need to switch to something other than wood for insulation. Delrin, PVC, acryllic, porcelain, glass, and polypropylene are all excellent insulators at higher frequencies.

If I had a Faraday cage around the doubler and arc, with it grounded with its own line to outside and be in a different room, by the sounds of it should be ok. I've got a wood work bench need to find some of those materials to coat it with.

Proud Mary

Tue Apr 09 2013, 08:10PM

Registered Member #543 Joined: Tue Feb 20 2007, 04:26PM
Location: UK
Posts: 4992

Take this as a Golden Rule: if you must make adjustments to a live circuit of anything more than 100 V or so - for example, when setting up RF circuits using thermionic valves - you must always keep one hand in your pocket at all times, so you cannot get an across-the-body shock - which is the most lethal kind.

Arcs and plasmas can be produced with a few kV and less. No need for hundreds of kV at all to do very interesting experiments along these lines.

Mads Barnkob

Tue Apr 09 2013, 08:31PM

Registered Member #1403 Joined: Tue Mar 18 2008, 06:05PM
Location: Denmark, Odense C
Posts: 1968

Cleaned thread of all unnecessary noise.
For those that like to play grammar police, stick to facebook.
Keep on topic.

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