Can anyone explain how to bleed the capacitance charge off of 13.8 kV wires so I can do work on the transformer? The transformer is a GE (model GEI-79025M) and we are using 600 Amp dead break connectors (3M 5815 Series). The dead break connectors have capacitive test point in the dead end plug but it is not conductive so I cannot use it to bleed the capacitance charge. I cannot use a hot stick to remove the dead break connector because they are the bolt on type. The 13.8 kV feed is an underground loop system going from one transformer to the next, with a total of 16 transformers.

Doesn't the utility usually take care of that when they open and ground the lines?
Joe

No. We are performing the function of the utility using inside wireman.

What you need is someone competent enough to do this sort of work.
Using in-experienced staff will end in disaster.
HV work is not like any other sort of electrical work, it is a totally different animal!

First,isolating the cable to the best of your ability, and companies regs.( using system maps, open isolating switches etc..) Install grounded parking stands in padmount. Using the socket adapter on your stick ( i think probably 1") untighten and remove each elbow, pushing back onto grounding stand.
If you even have ONE question as to whether or not the cable is de-energized, and no test points are available..?

SPIKE GROUND.

Better to spend time making up new elbows, then time in the burn ward.


HP

High-Potter,
Your post asks more questions than it actually answers.
Electrical Contractor.Net shall not be responsible for any advice given with respect to HV equipment and lines if something should go wrong.
Having un-qualified people working on HV gear is just asking for trouble!
Advice like this is NEVER given over the NET, you haven't even seen the installation and are going on a guys word.
You want to take that responsibility on?

Mike,

Although your advice is, as usual, superbly astute, and I know most experienced sparkies reading this thread will understand it, I know and understand that capacitance discharge can kill ya really quickly, I can only say that for the original question is to cut off and then let the capacitors self discharge for at least 12 hours before going anywhere them. The only answer is to cut the feed to all the transformers for at least 12 hours before servicing the stuff.

Dave,
I just have a problem with folks that are not conversant with HV work, as in clearances and PPE.
It only takes one hit with a HV voltage to bring you to your knees and kill you.
Be careful, is all I can say.

I have avoided this thread .... simply because HV stuff is beyond my competence.

Were I asked to work on HV gear, my answer is simple: NO. If I were told it was part of my job, I would insist on training ... and the training ought to be more than 'take this tool in there and twist the widget." Anyone who claims it's simple, any moron can do it - let them show you!

As an example, I recall the time the PoCo had to kill a transformer to a grocery store. After swinging the cover open, there was a plain steel panel, with only a simple switch handle visible. Did they just flip the handle? NO. The put on PPE, extended the hot stick, and turned the handle from 10 ft. away! One has to conclude that there were reasons for these precautions.

When it comes to HV, I don't even know how to flip a switch!

So Im confused here. Do you disagree with the method I discribed, or that advice given at all?

There are grown men on this board, who are professionals, and who post serious topics. You should either remove the "offending" original post, or open the topic up for discussion. ( And then you will get opinions from poster)
Situations like this ARE discussed over the net on a daily basis. Check out Powerlineman.com, Line-man.com. Heck even over on Mike Holt Forums.
I field questions at work regarding high voltage situations, and I answer them and offer my opinion to the best of my ability. I will do the same here.
Based on the posters specific situation, in no way did I offer "dangerous" advice. If you think I did, then I would be happy to discuss it. Email,phone...you name it.

HP

Thank you all for your input. As the regulator I have had concerns about using inside wiremen for medium voltage work and have shut them down for the last 2 years until they could show me the following:
1. Medium voltage Procedures
2. Medium voltage training program
3. Necessary tools & PPE
They came back and said they are ready to show me their program, training, PPE, and tools but when I looked at what they had, I found that they were not using grounding clusters because they said that 10 CFR 1910.269(n) did not require it if it was “impractical”. I still have them shut down and have been trying to show them that it is practical if they make minor modifications to the elbows during the next site shutdown. Installing ground clusters can be the difference between life and death and should not be eliminated because they are “impractical”. Our local utility linemen have been very helpful and knowledgeable in helping me present a practical solution. I was just using this form to see if there were other ideas out there.

Bull, MV switchgear always need to be grounded, and thier grounding clusters need to be tested and rated for the available fault current on the system they are grounding. You dont just go out and "Get trained up" on MV gear. Many companies require all work done on MV (And some LV stuff like switchgear and transformers) to be done only by a "Certified" company and "Certified" technition or testing engineer. Certified is through NETA or NICET.

Are far as the elbows, any real power system testing company will have the grounding elbows for this type of installation. Another good solution is to install the ball studs for grounding ( AB Chance or salisbury have these). There may be a better solution if I knew mor about the equipment.

In the meantime you can find a Certified" testing company in your area at www.netaworld.org

I have been around HV enough to be wary of it. It does not act like your typical 480v stuff.

It will reach out and touch you.
It will recharge the line you just shut down to nearly the same voltage it was at before you drained it.

Make sure you have the best gear available and take it slow.
Personnally, I'd hire GE or a local engineering firm with HV experience to send out a service tech.

I was goin to just read these post and be quiet,but you have some guys on here that have no idea of what they are talking about!!!
High voltage WILL NOT reach out and grab you!!!
Overhead-It can only "recharge" if there is a immediate source from which it can be "induced",hence grounding. Underground-can be induced or if left ungrounded for a long amount of time (days not hours) can build a capacitance charge.

Electricsquirrel.,

You have the right idea for correct producure to deal with MV/HV system Many pad mount most case it will have stand off point attachment however with some older one they don't have stand off so we have to make a grounding boot for it so we can able do it in safe manner..


NOTE :: to the rest of readers here please keep it civil if get out of hand with this I will or other Moderators will lock this thread.

Merci,Marc

So I take it you have never heard of MAD (Minimum Approach Distances) and Flash-over distances.

One other thing, tell that to the people that have climbed HV poles and towers without having even got close to the wires and have either been killed or very seriously burned as a result of their actions.

Electricsquirrel.,

I have see plenty arc flashover on MV / HV system and it don't take much to get them lit up.

I know Trumpy did mention " MAD " this is very important part for your safety The OSHA or other safety orgization have program for it.

Merci,Marc

MAD ,Minimum Approach Distance
2-15 kv is 2'1"
15-26 kv is 2'4"
36-46kv is 2'7"
I can go on all the way up to 500 kv.

What you don't know is MAD is how close you can get BEFORE you have take protective meassures, rubber gloves and rubber sleeves or "hot sticks".
I'm not going to start an argument here,BUT UNLESS you have ACTUALLY ever worked on high voltage under ground or overhead lines you are NOT qualified to tell me how it works!I worked distribution voltages up to 21 kv ,rubber gloved,hot stick, in a bucket truck and climbing poles.I have "BARE HANDED"(work on energized) 230 kv out of specially insulated trucks. I spent four years in school and countless hours on the job learning, I currently run a crew of 4 lineman building and repairing power lines,before that I was a JOURNEYMAN ELECTRICIAN,so I speak with some experience!Oh yeah,, I have an electrical engineering degree too.

Mr.Trumby,you must me confused ,I still firmly stand by my claim that "it" WILL NOT, jump out and grab you.A "crazed" drugged out person CAN climb a power pole and get with in an INCH of the energized conductor and NEVER get electrocuted UNLESS he TOUCH'S it.You HAVE to create a path to ground.If you haven't TOUCHED it you haven't created a path.( You could have a bad insulator,which could lead to tracking,which in that case the pole could be hot,whole different discussion)

Your claim of people getting burned from climbing HV( I've climbed plenty to do repairs) towers is partially correct,as you get closer to the energized conductor(wire)you enter a electro magnetic field,if you get partially into that field you will start to feel a charge called "INDUCTION".That comes from the HV "inducing" current onto you,if you have hold of a grounded tower leg,and enter that "FIELD" you have created a "difference" in potential,if that difference gets great enough it will start to burn you ,just like cooking in a microwave.

Like I said I'm NOT here to start any arguments,,,just get the facts right,,,,,,

Oh yeah,what happened to my post on the proper procedure to ground and bleed the cable as originally asked in this thread?

electricsquirrel,

You've already had one warning regarding your disrespectful tone. If you can't be civil, we can lock this thread or make it completely disappear if the need be.

Don't force us to do either one.

Where do you see anything disrespectful ??????

Could it be this?, maybe:

And by the way, don't use All Caps, it sounds like you are shouting, it is also rude.

I think I have something to contribute here.

I've done bench test testing of gear for a major testing lab, and one of the tests involves applying high voltages to terminals in equipment. If they're too close together, or the barriers aren't adequate, you can see the arc jump across the space from one terminal to another. Why do you think 480v gear is so much larger than 240v gear if the same amperage rating?

Likewise, I have seen the reasonably high voltage created by a car's HEI coil run along the surface of the coil wire, then jump across the 1" (or so) distance through dry air to make contact with a rubber fuel line.

There are also a number of documented PoCo accidents, where an arc jumped between substation gear when equipment, or personnel, filled the space between things. Oops.

Then there's everyone's favorite science project, the Jacob's ladder. Mine was making 3" arcs before it broke; the arcs started by jumping a 3/4" distance.

That electricity can jump distances, and that the distance is dependant upon voltage, is pretty basic science.

As for qualifications ... I'm not impressed. I never have been. An argument ought to be able to stand on it's own merits; ever great discovery was made by a nobody - Newton and Einstein were 'nobodies' when they put forth their theories. The "Greats" of their days are now largely forgotten.

ECN is fairly unique in the internet world, in that it has a great variety of professionals here. Master electricians to handymen, associated trades like engineers, linesmen, and inspectors.

And that's the key; "associated" trades, rather than any sort of system of 'rank.' I am endlessly amused at the ignorance of folks who think an engineer 'outranks' an electrician. That's a lot like expecting a 'mechanical engineer' to fix your car. Lots of luck with that!

I'll soon have the opportunity to work with some seriously high voltage. I look forward to the training. While I can make some guesses, I'm sure not going to look to a general internet forum for lessons! Discharging capacitors and grounding lines are basic skills in some areas, and if someone hasn't already been taught, I have some trouble telling them anything more than: stay away!

Squirrel, you're not the only one here with lines qualifications, nor the first to have gone through engineer school. You can 'bare hand' HV? Impressive - but can you fly the helicopter too? At least one of the posters here can. So make nice.

End of sermon.

A mad scientist answer to this problem:

The best option is to make the PoCo do it... its a dangerous operation that requires a specialized tool.

You would need a high voltage resistor (for safety, it MUST be rated for more than the expected voltage!) connected with high voltage cable to high voltage probes.

It could be built but beware, cut corners on the apparatus and DIE.

Building this is an exercise in engineering. You cant use just any HV resistor...it will be dissipating significant power and you don't want to burn it up. HV resistors cost $$$ and if it fries, it might arc over!

The whole thing would need to be potted in pure silicone for insulation.

Approximate calculations assuming a 200 watt resistor being fed 13.8kV... a 2Mohm resistor would do. (it would be well under its 200W rating at 13.8kV which is necessary considering its going to be potted)

What's scary is even if you build this thing and insulate it well AND you verify that the bank is at 0 volts....as soon as you take off this device, it may begin to partially recharge. The phenomenon is called dielectric absorption....charges in the dielectric migrate toward the plates and put some charge back on them! With a big cap, this residual charge could make you a crispy critter.

To prevent this, the caps must be shunted after discharging them.

Take all that in before tackling this. Safety issues aside; the tool could easily cost a few hundred dollars to make a safe one. HV probes, resistors and cables are expensive.