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1450 lbs of HV capacitors - gloves and boots?

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Patrick

Mon Feb 10 2014, 11:46PM

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

well if you do find lineman's gloves, i think they top out at 31 or 35 kv, you always where normal work gloves, like canvas heavy duty gloves.

so first, check the lineman's gloves each time before use, there yellow on the inside black on the outside. you puff them up with air, then check if the black outside shows any yellow, if so ... no go.

second, put the lineman's gloves on your hands.

third, put the canvas gloves on over the linemans gloves.

finally, the lineman's gloves are only meant to stop electricity, not nails or piercing or chaffing. The lineman's glove never touches anything but the inside of another glove.

doctor electrons

Fri Feb 14 2014, 03:17AM

Registered Member #2390 Joined: Sat Sept 26 2009, 02:04PM
Location: Milwaukee Wisconsin
Posts: 381

Id just like to add a few things here. I have done work on a few things along the order of what you are speaking of. Mainly
for caterpillar global mining. Without revealing any trade secrets i can attest to extremely large capacitor banks. Now, number one, without any
possible questions, doubts, or another terms any reasonable person would like to attach. The banks SHOULD be discharged before even approaching them,
the requirement when i worked on them was 12 feet. Now a little bit about the gloves, regarding which i had to attend safety meetings every morning before performing any work and was thoroughly informed on their value. The voltage rating on high voltage ( or arc flash, lineman, any name you would like to apply) are voltage rated not by the thickness of the insulating material. The voltage rating is given by the distance the voltage can "jump" and strike you in
the arm. It is also determined by the type of insulating material and its ability to withstand the voltages in question. As others have stated the only purpose for the outer, aka liners, is to protect the electrically insulating portion of the glove from puncture and cuts. And i need not remind anyone they require an inflation test before any work is performed, especially at the stated voltages. You do have a serious concern in front of you when dealing with devices like this. Lets all keep in mind fully insulated tools as well. I realize that we all love this stuff and appreciate its hazards but if there is any real moral of the story here its this. BE SAFE! One mistake when you're dealing with this level of energy is one too many! With proper knowledge and proper respect, tools, and lets reiterate again PROPER SAFETY EQUIPMENT ( aka ppe ) things like this are very safe. Lets remember theres plenty of bigger power out there!! As a hobbyist with the same passions as everyone else here, please don't consider this any type of lecture. I must admit i am a bit jealous of your "score" but i only put this out there to remind and not glorify any and all dangers associated. That being said.... AWESOME!!! ;) In addition to the gloves i was never required to wear boots other than plastic rather than steel toe. In addition i had to wear full arm and shoulder insulation as well as insulating protection for the chest and frontal thigh area. All of which is available on the web, the company who manufactured the gear i wear goes by the name salisbury, not to be confused with the steak ;)

GammaRay

Fri Feb 14 2014, 08:06AM

Registered Member #5323 Joined: Fri Jun 15 2012, 02:14PM
Location:
Posts: 104

I sincerely appreciate all the good advise. In the interest of safety, I am thinking about building a 'switch board' that is hard wired to each of the caps - located several feet away from the cap bank. The switch board would allow me to switch each of the 10 caps in and out of service without me actually having to physically get too close to these monsters. I am referring to manual type HV switches that I'd close and open by use of a long insulated pole. However, the exact type of HV switches to use are a mystery to me. I've googled HV switches, but not really finding switches designed to handle this type power. 1) Does this forum think the switch board idea is any good? 2) Can anyone point me in the right direction to sourcing the type of HV switches needed for the switch board idea? Thanks in advance.

Dr. Slack

Fri Feb 14 2014, 09:28AM

Registered Member #72 Joined: Thu Feb 09 2006, 08:29AM
Location: UK St. Albans
Posts: 1659

As you've found already, coming by HV switches is not trivial, and they are not trivial bits of equipment. Consider the current they have to carry, erosion if operated live, insulation flashover creepage distance to maintain, and we haven't even connected them to the caps yet by suitable wire. In short, forget switchgear. You're just building two projects, when you could be building one.

Now, if you want to add gizmos that will improve your safety, without causing more trouble than they're worth, consider a permanently attached shorting method on each capacitor, that you can operate remotely with your chicken stick, and that you can clearly, positively, see whether or not it is indeed shorting. I would advise something *really* simple, like an unpainted steel chain or a bare flexible cable terminated in a few links of chain, fixed to the case and ground terminal. To use, pick up the free end with a neo magnet or a hook on the end of your chicken stick, and drape it over the HT terminal. You don't get nearer to your caps than the length of your chicken stick until you can see all of them in place. I suspect if you try to design anything more 'real switch' looking, you will just be designing in failure modes and uncertainty.

radiotech

Mon Feb 17 2014, 09:00PM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

Are you a company or a person ? A company will have a safety program which assigns
responsibility for for compliance to electrical safety laws to supervisors licensed accordingly.

Forget the gloves. If anyone can get close to live circuits and they need insulation, the
task will have to be detailed.

I worked on and around subs up 230 kV. If a boss ever saw me do anything
wrong safety related.....consequences...

Gloves need a testing program and a test date marked on the glove. A lineman's stick
can be . used to operate switches , reset fuse drops, and to hold a high voltage tester.

Grainger has some info here. Class 4 are for 40 kV AC.

That is a nice lot of capacitors. operate them in a grounded cage.

GammaRay

Tue Feb 18 2014, 11:26PM

Registered Member #5323 Joined: Fri Jun 15 2012, 02:14PM
Location:
Posts: 104

These gloves

are available from Grainger rated at 26.5kV AC, the highest rating I can find so far. However, I am working with DC - I don't see any DC rating on their spec sheet. Anybody know what these gloves rated at 26.5kV AC would be rated for DC handling? (Would it be 26.5kV x 2 for DC use?)

Bored Chemist

Wed Feb 19 2014, 07:45PM

Registered Member #193 Joined: Fri Feb 17 2006, 07:04AM
Location: sheffield
Posts: 1022

If I have done the arithmetic correctly (Please feel free to check) then that bank stores roughly 30 times the energy delivered by an AK47 bullet

And you think gloves/ boots are going to help?
What are you planning to do with them? Write your name in them to make it easy to identify the corpse?

Mads Barnkob

Wed Feb 19 2014, 08:04PM

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

Bored Chemist wrote ...

If I have done the arithmetic correctly (Please feel free to check) then that bank stores roughly 30 times the energy delivered by an AK47 bullet

And you think gloves/ boots are going to help?
What are you planning to do with them? Write your name in them to make it easy to identify the corpse?

In physics, the kinetic energy of an object is the energy which it possesses due to its motion.

There is no reason to make this more dramatic than it really is, here are some other examples of electric energy

4000 Joule could lit up a 60W light bulb for 66 seconds, using a low energy 11W bulb it could be lit for 6 minutes.

4000 Joule is just enough for cooking 50 gram of water, to bring it from 20 degree Celsius to 100 degree Celsius.

Sure, such a capacitor at that voltage will blow your hand off and possibly leave you burned, but that is hopefully what we discussing how it can never happen.

There is in my opinion no reason to use high voltage gloves or boots, because as others also say, you should never operate these components with potential on and it can provide false figures of safety that you can suddenly just touch anything.

Go for the manual crowbar switches, chain for short circuiting and a bar to bolt on after than, install a volt meter across each cap, a LED and a incandescent lamp, have enough different methods of measurement so that 2 out of 3 can fail and you still have a warning about a capacitor being hot.

I dug into history of the high voltage forums to find a few of the threads with big discharge capacitors:

and

teravolt

Wed Feb 19 2014, 11:11PM

Registered Member #195 Joined: Fri Feb 17 2006, 08:27PM
Location: Berkeley, ca.
Posts: 1111

Using rubber ware is nice but can lead you into a faults sense of security. A protective area, crowbars, interlocks and a trust worthy HV meter is the way to go. We work on marxes and cap banks hear at work and we had a guy that was nearly electrocuted and sent to the hospital in January because he assumed there was no stored energy and forgot to check it out with a mete. When messing with those systems your biggest enemy is complacency and human error. That being also being said what are you going to do with them

Patrick

Thu Feb 20 2014, 12:23AM

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

[quote]
When messing with those systems your biggest enemy is complacency and human error.

yep! and the linemans gloves wouldnt do much if you tripped and fell across a conductor. In any case, would a neon lamp with resistor be suffcient to warn of HV ? perhaps he could make a portable device and pot it in epoxy, in a nice practical and easy to use form factor.

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