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ghostdog
03-06-2008, 07:55 AM
We all know that induction exists, But at our utility we have never really measured how much voltage gets induced onto a line. Recently we had 5 arresters blow on a line that is only 2 spans of overhead 3 phase wire. Feed from a riser and dead-ending at a 3 phase delta bank. We blew 4 arresters in about 1 hour. We ended up de-energizing the B phase and C phase line (leaving A hot). We then decided to check the B and C phase for voltage to see it A phase was tracking onto the ground and shorting the arresters. When we checked there was 2000V on B phase and 1500V on C phase. It was a sunny day with no humidity. Through other testing we found this to be seperate from the arresters blowing and it was simply induction. We were taken back by the amount of voltage that was being induced... So please remember it is not dead until it is grounded.

loodvig
03-06-2008, 09:25 AM
A couple of questions. First what is the primary voltage? Second was the delta bank cleared from the phases when you killed the two phases? Or was the bank back feeding?

wtdoor67
03-06-2008, 10:17 AM
the same thing I do. Your problem here sounds like Ferroresonance. Having a delta bank on the dead end is a giveaway.

I have worked on plenty of underbuild lines where induction is always present but it has no effect on the normal operation of the underbuild line. When the underbuild line is de-energized the induced voltage will show up when you test it with a volt meter but it is a fluctuating voltage. It will hurt a lineman and has killed hands but evidently it is unusable for electrical purposes.

I remember a single phase line that underbuilt a 138 Kv line. We killed out the single phase but you could still get a reading on the transformer that was hooked to the single phase. It would peg the volt meter and then go to zero, repeatedly.

Need some good engineer to explain it I guess. Maybe ask Swamp gas. He's pretty technical. Heh.

ghostdog
03-06-2008, 05:04 PM
The primary voltage is 8kV. The delta bank was open when the B and C phase voltage was measured. This is not a underbuild line it is a tangent 3 phase line. We are checking into the Ferroresonence (for the arrester blows) with our local Ferro Guru.

lewy
03-06-2008, 05:25 PM
If the line was not an underbuild was it under or adjacent to a high tension line? induction had to come from somewhere.
What size of arrester were you using we use 6 kv on our 8.3/4.8 kv lines.
I personally have never experienced or heard of the guys around here experiencing ferroresonance , but I understand it is on the higher voltages (our highest distribution voltage is 27.6/16 kv),

PA BEN
03-06-2008, 09:45 PM
Sounds like back feed. Wouldn't induction bleed off through the meter?

wtdoor67
03-06-2008, 10:06 PM
one phase energized along side two phases that are de-energized then yes there will be induction on the two de-energized phases. This doesn't explain the blowing of the arresters.

You would have to give us a step by step explanation of the events I guess. Have you ruled out a bad lot of arresters?

Wrong voltage arresters?

loodvig
03-07-2008, 10:09 AM
2000v on B phase is alot. And like Ben said why didn't it bleed off through the meter? Where are the LA's mounted on the cans or up on the arms? I don't know why I ask that just wanna know I guess.

ghostdog
03-07-2008, 10:24 AM
The line induction was from A phase being erergized while B and C were de-energized. This is a completely seperate issue from the aresters blowing. I just thought I would remind everyone that induction is real and it does happen. The arrester blows we believe were from the way that the lineman who was working the outage closed the feed to the delta bank. Everytime he would close the riser to pick up the delta bank he left the Delta bank cutouts closed.... This becomes a problem when A and B phases are hot because you are back feeding the C phase transformer and the arresters with about 4600V. So when he closed in C phase at the riser the arresters both saw about 12500V. They are 10kV arresters. The Engineers seem to agree with our theroy. We have replaced the arresters and had them close the riser first then the bank and it has been fine ever since.

lewy
03-07-2008, 03:48 PM
If you have induction on your line the only way to control it is to ground the line just by testing will not drain it, only the the grounds will & once you remove the grounds it will be back. That is part of the reason our province brought in a new rule that when you are working on a line it will either be grounded or energized no more working on isolated primary.

wtdoor67
03-07-2008, 06:51 PM
The line induction was from A phase being erergized while B and C were de-energized. This is a completely seperate issue from the aresters blowing. I just thought I would remind everyone that induction is real and it does happen. The arrester blows we believe were from the way that the lineman who was working the outage closed the feed to the delta bank. Everytime he would close the riser to pick up the delta bank he left the Delta bank cutouts closed.... This becomes a problem when A and B phases are hot because you are back feeding the C phase transformer and the arresters with about 4600V. So when he closed in C phase at the riser the arresters both saw about 12500V. They are 10kV arresters. The Engineers seem to agree with our theroy. We have replaced the arresters and had them close the riser first then the bank and it has been fine ever since.

After you described the sequence of events, yes it was ferroresonance.

Induction is always there on any ungrounded line that is insulated. If it doesn't pick it up from other nearby energized lines it may even pick it up from the wind blowing. Especially if there's a little dust in the air. We used to sorta ignore it if you had on thick leather gloves but now and then you would have to ground it to keep it from eating on you.

Dorchester
03-10-2008, 10:59 AM
Sounds like back feed. Wouldn't induction bleed off through the meter?

Not if it's a digital meter.
Digital meters are incapable of breaking down capacitively coupled voltages.

lewy
03-10-2008, 11:17 AM
Induction if present will not be bled off by any kind of meter.
The meter just shows that it is there the only way to control induction is with grounds

old lineman
03-10-2008, 08:30 PM
After you described the sequence of events, yes it was ferroresonance.

Induction is always there on any ungrounded line that is insulated. If it doesn't pick it up from other nearby energized lines it may even pick it up from the wind blowing. Especially if there's a little dust in the air. We used to sorta ignore it if you had on thick leather gloves but now and then you would have to ground it to keep it from eating on you.

Water flowing under the conductors can also cause induction.
I am surprised that you promoted thick leather gloves as a guard against induction.
Induction is an electrical charge. Rubber gloves are a barrier against a worker having current flow through the body.
Human beings cannot tolerate current flow of any magnitude.
When did leather become a barrier against electricity.
Perfectly dry, uncontaminated, unblemished leather will afford an unpredictable level of protection.
Any one of the aforementioned that becomes comprimised will allow current to flow. Induction is deadly. Wear rubber gloves within leather covers or ground it.
Don't be foolish.
The Old Lineman

lewy
03-10-2008, 08:43 PM
Water flowing under the conductors can also cause induction.
I am surprised that you promoted thick leather gloves as a guard against induction.
Induction is an electrical charge. Rubber gloves are a barrier against a worker having current flow through the body.
Human beings cannot tolerate current flow of any magnitude.
When did leather become a barrier against electricity.
Perfectly dry, uncontaminated, unblemished leather will afford an unpredictable level of protection.
Any one of the aforementioned that becomes comprimised will allow current to flow. Induction is deadly. Wear rubber gloves within leather covers or ground it.
Don't be foolish.
The Old Lineman

Thats why in Ontario you would have to ground the line
If the line is not energized it has to be grounded before we can work on it, no more working on isolated lines

old lineman
03-11-2008, 05:36 PM
Thats why in Ontario you would have to ground the line
If the line is not energized it has to be grounded before we can work on it, no more working on isolated lines


Amen!
The Old Lineman

wtdoor67
03-11-2008, 06:07 PM
[QUOTE=old lineman;41347]Water flowing under the conductors can also cause induction.
I am surprised that you promoted thick leather gloves as a guard against induction.
Induction is an electrical charge. Rubber gloves are a barrier against a worker having current flow through the body.
Human beings cannot tolerate current flow of any magnitude.
When did leather become a barrier against electricity.
Perfectly dry, uncontaminated, unblemished leather will afford an unpredictable level of protection.
Any one of the aforementioned that becomes comprimised will allow current to flow. Induction is deadly. Wear rubber gloves within leather covers or ground it.
Don't be foolish.
The Old Lineman[/QUOTE


on the property of an IOU whose safety regulations stated that voltage of 300 volts phase to phase and lower could be worked with "dry leather gloves with no holes in them". Everybody did it that way and nobody suffered any ill effects. I admit that is no longer their rule.

Worked on a 345 job once where periodically the clippers would complain of induction at times. Their solution. Add more grounds. It was already grounded but it seemed the farther you got down the line clipping and the farther from the grounds it would start eating on you.

old lineman
03-12-2008, 09:17 PM
[QUOTE=old lineman;41347]Water flowing under the conductors can also cause induction.
I am surprised that you promoted thick leather gloves as a guard against induction.
Induction is an electrical charge. Rubber gloves are a barrier against a worker having current flow through the body.
Human beings cannot tolerate current flow of any magnitude.
When did leather become a barrier against electricity.
Perfectly dry, uncontaminated, unblemished leather will afford an unpredictable level of protection.
Any one of the aforementioned that becomes comprimised will allow current to flow. Induction is deadly. Wear rubber gloves within leather covers or ground it.
Don't be foolish.
The Old Lineman[/QUOTE


on the property of an IOU whose safety regulations stated that voltage of 300 volts phase to phase and lower could be worked with "dry leather gloves with no holes in them". Everybody did it that way and nobody suffered any ill effects. I admit that is no longer their rule.

Worked on a 345 job once where periodically the clippers would complain of induction at times. Their solution. Add more grounds. It was already grounded but it seemed the farther you got down the line clipping and the farther from the grounds it would start eating on you.

First a couple of questions.
Do your rubber gloves have to be laboratory test at given intervals and to certain voltage levels by a certified lab?
ASTM sets the standard.
Have you ever heard the term 'personal grounds'?
Personal gives the impression that they are yours. They can't be yours if they are away from your work site. If you are working in an area of induction they should be with you.
The farther they are away from you the more difference in potential there will be. Induction flucuates wildy from one second to another, therefore, your grounds must be robust and in top condition to ensure the lowest possible resistence to current flow.
If there is more than one work crew they all have to install their own personal grounds.
Don't forget about the maximum protection that equipotential grounding affords.
Leather gloves are never dielectrically tested, therefore, CANNOT be used as a personal barrier against electrical current.
Also don't forget 120 volts kills. It's the current and there is enough in a 120 volt circuit.
Your employer cannot force you to take that risk and if you do and something goes they will point every finger at you.
If they don't they are really out of step with current safety philosophy.
The Old Lineman

wtdoor67
03-12-2008, 10:38 PM
safety man. Right?

The incidents referred to happened in 1971.

Actually it's not the 120 volts, it's the amps,right? I think I read once that under the right conditions, 1 milliamp can kill you.

I don't remember equipotential being around then. This was in the days of bracket grounding and everyone just added grounds.

Nothing like a lineman who gets into the safety department. All of a sudden he is most self righteous and never violated a rule when he was a hand. I can honestly say I never worked with anyone for any length of time who did not violate a safety rule.

The latest take I was given on EPZ was that it was voodoo science. The AEP gurus haven't made up their mind after about 5 yrs. Some are running with it though.

Some safety rules should never be broken, but others, who knows?

Meat
03-12-2008, 11:14 PM
Wtdoor I usually enjoy reading your posts and have even learned a thing or two but this one puzzles me.EPZ is voodoo science? A theory maybe but a "theory" has an abundance of evidence to support it in most cases.Like the Old Lineman said the current safety philosophy supports this type of grounding and our state requires it.I understand your comments about breaking a rule now and then( airmailing a pole top)but this ones a little more serious in my opinion. It's easier not to EPZ ground but safer? I'm not convinced.Meat.

wtdoor67
03-12-2008, 11:20 PM
Labs and AEP in Columbus, Ohio. I don't think there is a safe way to ground.

johnbellamy
03-12-2008, 11:30 PM
I understand if on the pole if you E.P.G , pole bracket below your feet, you are in the E.P. zone.

My questions are if you are in a bucket,at a differnt potential, how do you E.P.G?

My next question is working mid span, How do you E.P.G.

An example, on a 115kv line, Removing a tree, and then repairiing the wire, either the wire is together, or broken in to. Mid span, between two H structures.

No big words please, Thanks.

wtdoor67
03-13-2008, 08:22 AM
.let me say I am retired. About a year now. I am so relieved and was mighty sick of some of the people I worked with, but there were some jewels and I admit I miss some of the work but it's so nice not to have to show up anymore.

I do not remember the details for all situations for EPZ grounding. I only remember the single pole setup with a man on the pole.

The first grounding I was exposed to was bracket grounding, which I suppose most are familiar with. This was done under the old belief that "electricity takes the path of least resistance." Since it was simple everyone seemed to do it.

In 1973, I was exposed to the one that Swampgas mentioned. The AB Chance guy came around and set up the little mock line and closed the switch and the little guy on the pole lit up with bracket grounding. Then he moved the grounds to the pole the lineman was on and he no longer lit up. This demonstrated that point of contact grounding put you at the same potential as the line and therefore you were like a bird on a wire. I never saw anybody consistently use this method.

I then worked at an entity that was fond of ground switches on their transmission lines and always closed in ground switches on both ends and then bracket grounded while working on the cleared lines.

Eventually I was exposed to EPZ grounding with AEP. This was considered the primo way to ground for about 5 or 6 months and then they released the information that Dolan or Nolan Labs in Columbus,Ohio had tested the EPZ method extensively and declared that it was not a valid way to ground since your hooks digging into the pole placed you at a different potential as the grounds therefore placing you at hazard. They then instructed us to EPZ ground the line but wear your hi volt rubber gloves. There was talk about driving something such as a pole step into the heart of the pole and then that would suffice. To my knowledge as of today they still haven't come up with a valid surefire way to ground.

I became cynical about the whole subject and wearing rubber gloves and being exposed to voltage perhaps higher than your glove rating just seemed like BS to me.

However I have never heard of an incident such as a higher voltage or whatever making contact with a grounded line and killing or injuring anyone. I just think that grounding and assuming you are safe is probably not so. I think there is not a valid way to protect against all possibilities. Probably a 100% way to protect a lineman would be so much trouble that no utility co. is going to do it.

There will be safety people chime in probably and insist they have all the answers. I don't believe them.

johnbellamy
03-13-2008, 10:22 AM
I understand that voltage will take all paths to ground but the better the path the easier the flow, I don't buy what they are selling either.


At camp Rilea, second year we had a training yard for hot sticking, secondary voltage, on primary wires with all hardware bonded to the neut, with liitle wires, fused litely so if you made contact, or energized anything you shouldn't you would know as well as everybody else.

One demonstration that I did was they had me E.P.G off the pole then go in the zone grab to phases then energize the line, the fuses blew, and I felt nothing, but this was secondary voltage.

But the practicality that Making a EPZ when working damaged lines does not seem to pratical to me.

This whole driving a ground rod and making another path seems more dangerous for the people working the ground because of the differnce of potental, or step potental.

I have seen the video's, and simulations, but the only time I have got my dick knocked in the dirt, was getting between things with any difference of potental,

Thanks. Can you help me out on the not grounding the case of a transformer one? I stll don't get that onr either. Nice to have you on the board, sounds like you have done your homework.

wtdoor67
03-13-2008, 11:11 AM
have been intrigued by the not grounding of the case of the pots. I understand that it is a small portion of Calif. that follows this practice. I don't know what co. it is, but I think it is a utility co. Maybe somebody will reveal it.

99% of house voltage pots come from the factory with a ground strap on them and of course practically all 277/480 pots come with a strap on the ground lug also. If the neutral service wire is connected to the X2 and also the system neutral then in a roundabout way the case of the pot is grounded. However on perhaps a delta or unigrounded system it might be that the case of the pot could be ungrounded except for the ground rod on the customer's end.

I can see no reason for not grounding the case of the pot. It is just another little safety factor that increases your safety. It is my understanding that even on a 2 bushing primary pot that should the primary winding become in contact with the inside case of the pot that it could cause the case to become energized.

Some will say that it would blow the fuse on the pot. I have seen many pots incorrectly fused and also on a delta connected pot probably only one fuse will blow. I wouldn't want to touch with my bare hand or leather glove the case of an ungrounded pot with one fuse blown. Then they will say you should have your rubber gloves on. Under some conditions of trouble, on a dark and stormy night I'm confident that people will follow all rules.

Like a trouble man I talked to once. He said the good thing about working alone was that he had some pretty good screwups, but nobody knew of them but himself.

lewy
03-13-2008, 04:38 PM
We use EPG & I like it for small jobs I find it easier.
We use Hubbards on all of our poles as well as a band that has to go around the pole when we are grounding.
We all know that it is the current that kills & if every thing is at the same potential not necessarily 0 potential we will have no current flow
As far as EPG out of a bucket if you are mid span you are allready in an EPZ Because of the insulation of the boom & all the phase are tied together when you are near the pole as long as you follow EPG you would be fine
If you are using an RBD it would have to be grounded

johnbellamy
03-13-2008, 08:26 PM
We use EPG & I like it for small jobs I find it easier.
We use Hubbards on all of our poles as well as a band that has to go around the pole when we are grounding.
We all know that it is the current that kills & if every thing is at the same potential not necessarily 0 potential we will have no current flow
As far as EPG out of a bucket if you are mid span you are allready in an EPZ Because of the insulation of the boom & all the phase are tied together when you are near the pole as long as you follow EPG you would be fine
If you are using an RBD it would have to be grounded

So you don't need to single point ground because you are Isolated, just tie all of your wires togther.

lewy
03-13-2008, 08:36 PM
So you don't need to single point ground because you are Isolated, just tie all of your wires togther.

& grounded only if you were working mid span

BULLogna
03-13-2008, 08:50 PM
when working from a bucket, single point grounding is the way. you don't need a ep zone. One thing i always found interesting with all grounding is: if you are the second crew on the same circuit but in a different location and the first crew has already grounded there job site. that second set of grounds can be very exciting to install. I guess cause your completing an induced circuit from ground through wire and back to ground. so its a bad idea to install grounds by hand. Yet i still see it done?


_____________________________________
"thats where the trouble is" Slim & Red

barehander
03-13-2008, 09:46 PM
I understand if on the pole if you E.P.G , pole bracket below your feet, you are in the E.P. zone.

1. My questions are if you are in a bucket,at a differnt potential, how do you E.P.G?

2. My next question is working mid span, How do you E.P.G.

3. An example, on a 115kv line, Removing a tree, and then repairiing the wire, either the wire is together, or broken in to. Mid span, between two H structures.

No big words please, Thanks.

First off, good to see you back getting involved Mr. Bellamy.
And this was discussed awhile ago, here......
http://www.powerlineman.com/lforum/showthread.php?t=2886
where I put my 2 cents in about the broken cond. part of question 3.....
#1....if your bucket is tested for rubber gloving at the voltage you are working, you would, (as we call it epz,) still epg with pole band in case of incidental contact with an arm or the pole or other things on the pole. You wouldn't be a different potential cause you would be insulated and isolated in your bucket.
#2....Same principle as question 1, but let's say you are using a boom truck with a basket attached. You would ground midspan and ground the vehicle to the ground rod, placing you at the same potential. In our Subs, that's how they do work with manlifts and boom trucks, putting everything onto the ground grid.
#3.....Our buckets are tested @ 54kv and if you don't know by now, I do Transmission. We did this just 2 wks ago. Because of a car-pole awhile ago, the crew that did the repairs at night did not sag the cond. high enough above an inerset 12kv pole. We went mid-span, EPZ'd, grounded our truck, and went to work. And before we cut the wire to splice, jumpered across it, keeping everything the same potential....wa-la..job done...

old lineman
03-13-2008, 10:18 PM
when working from a bucket, single point grounding is the way. you don't need a ep zone. One thing i always found interesting with all grounding is: if you are the second crew on the same circuit but in a different location and the first crew has already grounded there job site. that second set of grounds can be very exciting to install. I guess cause your completing an induced circuit from ground through wire and back to ground. so its a bad idea to install grounds by hand. Yet i still see it done?


_____________________________________
"thats where the trouble is" Slim & Red

When working from a pole on a grounded conductor that unexpectedly becomes energized there will be a momentary potential rise. The worker will become a parallel path to another potential. That current flow can be lethal.
You should understand that.
An EPZ will energize the pole below the workers feet. Since the potential is the same because of the cable leading to the pole will energize the pole at the same potential as the conductor there will be no current flow.
NO POTENTIAL DIFFERNCE NO CURRENT FLOW. The worker remains safe.
Almost everyone understands this.
Now to your comment where a worker is working from a bucket.
You say an EPZ is unnecessary. I say hold on a minute.
Visualize this, the same situation occurs as mentioned and the conductor becomes momentarily energized. The worker in the bucket just happens to have his shoulder up against the structure at that instant. The bucket is nullified and he is virtually the same as the lineman on the pole.
EPZ is required in this case as well. Think about it!
Seeing grounds put on by hands is crazy. That's what grip-alls are for.
Surely these guys know better.
The Old Lineman

Meat
03-13-2008, 10:30 PM
Old lineman is batting a thousand in this thread.At least IMHO.Good job!Meat.

johnbellamy
03-13-2008, 11:27 PM
First off, good to see you back getting involved Mr. Bellamy.
And this was discussed awhile ago, here......
http://www.powerlineman.com/lforum/showthread.php?t=2886
where I put my 2 cents in about the broken cond. part of question 3.....
#1....if your bucket is tested for rubber gloving at the voltage you are working, you would, (as we call it epz,) still epg with pole band in case of incidental contact with an arm or the pole or other things on the pole. You wouldn't be a different potential cause you would be insulated and isolated in your bucket.
#2....Same principle as question 1, but let's say you are using a boom truck with a basket attached. You would ground midspan and ground the vehicle to the ground rod, placing you at the same potential. In our Subs, that's how they do work with manlifts and boom trucks, putting everything onto the ground grid.
#3.....Our buckets are tested @ 54kv and if you don't know by now, I do Transmission. We did this just 2 wks ago. Because of a car-pole awhile ago, the crew that did the repairs at night did not sag the cond. high enough above an inerset 12kv pole. We went mid-span, EPZ'd, grounded our truck, and went to work. And before we cut the wire to splice, jumpered across it, keeping everything the same potential....wa-la..job done...

So I don't glove anything over 5kv, (un less, sometimes, I not going to tell you I have'nt.) Transmission I have worked hot, 69kv,115kv,and 230kv, nothing higher.

We have alot of tree damage on 115, and 69kv, what I have done on a isolated piece of a 115kv loop, is close the ground switch on one end, (if available)at the site, identify and test the short the three wires out, then do my repairs, allways macking any broken connductor and never cutting the wire to splice without doing the same, I never ware rubber gloves, just leathers and have never had a problem for the last 11 years.

When working 115kv switch maintance, we would mack the switch out, drop the jumpers, and then adjust and repair the switch, when on the pole the bite was not as bad when touching the hardware, than when you would touch it out of a insulated bucket, I also could ware no gloves, just slam on the hardware with my barehand, but I had to keep that hand on at all times, If the guy in the bucket would touch me we would get slammed, like I have stated before the difference of potental allways gets me, Just like working underbuild on 115 it is hotter than hell to work, any suggestion to lessen the bite?

barehander
03-14-2008, 10:08 AM
So I don't glove anything over 5kv, (un less, sometimes, I not going to tell you I have'nt.) Transmission I have worked hot, 69kv,115kv,and 230kv, nothing higher.

#1...We have alot of tree damage on 115, and 69kv, what I have done on a isolated piece of a 115kv loop, is close the ground switch on one end, (if available)at the site, identify and test the short the three wires out, then do my repairs, allways macking any broken connductor and never cutting the wire to splice without doing the same, I never ware rubber gloves, just leathers and have never had a problem for the last 11 years.

#2...When working 115kv switch maintance, we would mack the switch out, drop the jumpers, and then adjust and repair the switch, when on the pole the bite was not as bad when touching the hardware, than when you would touch it out of a insulated bucket, I also could ware no gloves, just slam on the hardware with my barehand, but I had to keep that hand on at all times, If the guy in the bucket would touch me we would get slammed, like I have stated before the difference of potental allways gets me, Just like working underbuild on 115 it is hotter than hell to work, any suggestion to lessen the bite?

First of all, grounding is the most mis-understood tool that a lineman has. All you have to do is read this thread & the link I posted here to see all the ways people do it. OldLineman & a few others understand about placing everything at the same potential. There is step and touch potentials, the introduction of foreign grounds at a location, such as phone messenger, cable TV, guy wires, etc. Most Lineman do not know what the fault duties of the lines they work on. They do not understand about grounding for the fault duties of the Transmission lines that cross over the lines they are working on, just in case the Transmission drops onto their line. Most Lineman do not know, for example, that if you have a line coming out of a Sub. that has a fault duty of 35,000amps, how many miles of line does it take before the fault duty falls below 15,000amps.
I have the answers for your questions, but, and I'm not picking on you, I just want everyone to know how much danger is present in what you say you do.
Before I answer, I have a question about #2. This is strictly about Transmission. Why do you think the hardware on that switch is so hot? Do you have any rules that talk about working on hardware of Transmission? Have you ever tested an insulator for leakage?

BigClive
03-14-2008, 01:17 PM
It's not just current capacity of a ground bond either. The resistance of the connection itself is important. If you consider an instantaneous short circuit current of 1000A then a 1 ohm resistance in a bond will result in a potential difference during the short of 1kV. It's most likely the resistance would be in the connection itself as opposed to the wire. A chewed up, oxidised, dirty connector that's just casually clipped onto an equally weather beaten and oxidised line could potentially have enough insulating crud present to allow an induction potential of fatal levels to remain present on a cable.

lewy
03-14-2008, 04:28 PM
So I don't glove anything over 5kv, (un less, sometimes, I not going to tell you I have'nt.) Transmission I have worked hot, 69kv,115kv,and 230kv, nothing higher.

We have alot of tree damage on 115, and 69kv, what I have done on a isolated piece of a 115kv loop, is close the ground switch on one end, (if available)at the site, identify and test the short the three wires out, then do my repairs, allways macking any broken connductor and never cutting the wire to splice without doing the same, I never ware rubber gloves, just leathers and have never had a problem for the last 11 years.

When working 115kv switch maintance, we would mack the switch out, drop the jumpers, and then adjust and repair the switch, when on the pole the bite was not as bad when touching the hardware, than when you would touch it out of a insulated bucket, I also could ware no gloves, just slam on the hardware with my barehand, but I had to keep that hand on at all times, If the guy in the bucket would touch me we would get slammed, like I have stated before the difference of potental allways gets me, Just like working underbuild on 115 it is hotter than hell to work, any suggestion to lessen the bite?

There have been times when working on a properly grounded line below a high tension line when on the pole & I would feel nothing , but the man in the bucket would be getting lifters every time he would touch the grounded line & vice versa, the only reason I can come up with is the induction is charging you & you are discharging every time you touch the line.
We just wear our gloves if it is bad , you could try your barehand grids & bond on first(seems like a lot of work), something I have never tryed .

BigClive
03-14-2008, 04:52 PM
That sounds like an instance where one of the high resistance grounding straps used in electronics would help. It's an elasticated or velcro pad that goes round the wrist and is then connected to a ground point via a resistor for safety. It's purpose is to drain away any static charge on your body.

Unfortunately where linework is involved I don't think I'd recommend attaching yourself to even a dead line in case it was accidentally energised.

lewy
03-14-2008, 05:32 PM
That sounds like an instance where one of the high resistance grounding straps used in electronics would help. It's an elasticated or velcro pad that goes round the wrist and is then connected to a ground point via a resistor for safety. It's purpose is to drain away any static charge on your body.

Unfortunately where linework is involved I don't think I'd recommend attaching yourself to even a dead line in case it was accidentally energised. If you were bonded on & the line became energized you would be at the same potential , it is the same principal as barehanding.
It is something that no one does when working on grounded lines (as far as I know) it was just a thought on how to deal with getting lifters out of a bucket when working on a grounded line, when you are dealing with induction

BigClive
03-14-2008, 05:59 PM
True enough, but you would be referenced to the line at all times even in instances when you might not have been touching it directly, like when you used the controls on the bucket.

lewy
03-14-2008, 06:56 PM
Thats the idea, for everything to be at the same potential the entire head of the boom, when you are actually barehanding everything is bonded together at the top of the boom( conrtols & both buckets)

johnbellamy
03-14-2008, 08:11 PM
[/B]First of all, grounding is the most mis-understood tool that a lineman has. All you have to do is read this thread & the link I posted here to see all the ways people do it. OldLineman & a few others understand about placing everything at the same potential. There is step and touch potentials, the introduction of foreign grounds at a location, such as phone messenger, cable TV, guy wires, etc. Most Lineman do not know what the fault duties of the lines they work on. They do not understand about grounding for the fault duties of the Transmission lines that cross over the lines they are working on, just in case the Transmission drops onto their line. Most Lineman do not know, for example, that if you have a line coming out of a Sub. that has a fault duty of 35,000amps, how many miles of line does it take before the fault duty falls below 15,000amps.
I have the answers for your questions, but, and I'm not picking on you, I just want everyone to know how much danger is present in what you say you do.
Before I answer, I have a question about #2. This is strictly about Transmission. Why do you think the hardware on that switch is so hot? Do you have any rules that talk about working on hardware of Transmission? Have you ever tested an insulator for leakage?

If I can learn, or at least have a better understanding of what is going on. I am here to learn.

The fact of the matter is I don't know why the hardware of a switch is so hot, I have never tested an transmission insulator for leakage, I think it is from the electro magnetic field that causes this charge when you get in the zone, also the windier it is the worst it is.

I have not had the training or have not done any barehanding on transmission voltages. As far as grounding with a pole bracket, I don't know many that do this that I have worked with, I am just being honest.

Thanks.

barehander
03-14-2008, 10:55 PM
If you were bonded on & the line became energized you would be at the same potential , it is the same principal as barehanding.
It is something that no one does when working on grounded lines (as far as I know) it was just a thought on how to deal with getting lifters out of a bucket when working on a grounded line, when you are dealing with induction

Well, I and my crew do that. An example is where my office is, in a Sub with 7 500kv lines into it. Our job was to remove the old wave traps and CT's, and close the jumpers on these double deadends cause they were reconfiguring the Sub. There are bus ties everywhere and everything around us was hot. 2 of my guys were up in the bucket working and all you could hear was ouch, ouch ( the cleaned up version). anytime they touched the wire, a tool, the bucket controls, or each other, they were getting the crap knocked out of them. By lunch they were worn out. They decided to go get their barehand jackets and gloves. We have a metal hanger bracket on the outside of our bucket to hang stuff, grunt bags, etc. The jacket has 2 straps with bond-on clamps and they both put 1 clamp on that, 1 guy put his other on the control handle, and the other guy clamped to the wire......they were now at the same potential with each other, the wire, the controls. that's how we work those projects now, even though it's grounded.......

For all of you, this what induction looks like.......
1251

barehander
03-15-2008, 12:04 AM
If I can learn, or at least have a better understanding of what is going on. I am here to learn.

The fact of the matter is I don't know why the hardware of a switch is so hot, I have never tested an transmission insulator for leakage, I think it is from the electro magnetic field that causes this charge when you get in the zone, also the windier it is the worst it is.

I have not had the training or have not done any barehanding on transmission voltages. As far as grounding with a pole bracket, I don't know many that do this that I have worked with, I am just being honest.

Thanks.

I'm getting ready to go to the central coast of Ca. for the weekend (best wine in the world) and I wanted to ask this question of you and others that might answer your question.
Lets say you have a 115kv switch and you needed to Phase across it for some reason and all you had was a 12kv phasing set.
How would you do it?

johnbellamy
03-15-2008, 12:43 AM
I'm getting ready to go to the central coast of Ca. for the weekend (best wine in the world) and I wanted to ask this question of you and others that might answer your question.
Lets say you have a 115kv switch and you needed to Phase across it for some reason and all you had was a 12kv phasing set.
How would you do it?

So I wouldn't. Also if the switch is closed, It would be in phase.

What kind of equipment would you use?

lewy
03-15-2008, 07:13 AM
Thanks barehander I knew it would work, where I work we do not work anything over 44 & when we barehand it we do not need (have) the suits we just put the grids in the buckets, but we have never used them when dealing with induction on grounded lines

barehander
03-15-2008, 11:14 AM
Quote:
Originally Posted by barehander http://www.powerlineman.com/lforum/images/buttons/viewpost.gif (http://www.powerlineman.com/lforum/showthread.php?p=41576#post41576)
I'm getting ready to go to the central coast of Ca. for the weekend (best wine in the world) and I wanted to ask this question of you and others that might answer your question.
Lets say you have a 115kv switch and you needed to Phase across it for some reason and all you had was a 12kv phasing set.
How would you do it?

So I wouldn't. Also if the switch is closed, It would be in phase.

What kind of equipment would you use?

Well, this is part of the answer about touching the hardware on a 115kv switch and why it knocks the crap out if you. There can be induction involved, but a lot of it could be voltage creep. With the switch open, place your phasing set on the first bell of the switch. You probably might get a reading, if not, go to the second bell, and so on. I would hazard a guess that 1 or 2 bells would do the trick......
Where I work we cannot touch the hardware of any Transmission pole without testing and grounding it because of the voltage creepage & induction. You really have no idea how much is on that steel.

For phasing Transmission, we use a wireless phasing set, having no cord is wonderful......

johnbellamy
03-15-2008, 12:15 PM
Quote:
Originally Posted by barehander http://www.powerlineman.com/lforum/images/buttons/viewpost.gif (http://www.powerlineman.com/lforum/showthread.php?p=41576#post41576)
I'm getting ready to go to the central coast of Ca. for the weekend (best wine in the world) and I wanted to ask this question of you and others that might answer your question.
Lets say you have a 115kv switch and you needed to Phase across it for some reason and all you had was a 12kv phasing set.
How would you do it?

So I wouldn't. Also if the switch is closed, It would be in phase.

What kind of equipment would you use?

Well, this is part of the answer about touching the hardware on a 115kv switch and why it knocks the crap out if you. There can be induction involved, but a lot of it could be voltage creep. With the switch open, place your phasing set on the first bell of the switch. You probably might get a reading, if not, go to the second bell, and so on. I would hazard a guess that 1 or 2 bells would do the trick......
Where I work we cannot touch the hardware of any Transmission pole without testing and grounding it because of the voltage creepage & induction. You really have no idea how much is on that steel.

For phasing Transmission, we use a wireless phasing set, having no cord is wonderful......


Thanks, A simple way to test, with a piece of equipment most crews have avaliable.

The induction picture, I have done that with my bare fingers, the switchs hardware is tied to a pole ground, other than the switch contact arms of course, so as long as I slam on hard to the hardware out of a insulated bucket , because you cannot creep up on it slow, I feel nothing, Is that because I am at the same potental as the grounded hardware of the switch?

People have said use your rubber gloves, but when you put them on, you get ate up , feels like needles jumpin back and forth between the rubbers and you bare skin.

Another one that gets me is the driving a ground rod to bond equipment, such as cranes, and digger derrick trucks, when replacing poles, and hanging arms, seems like it makes a dangerous situation for people working the ground. It is also hard to drive ground rod into rock, and earth,ground, sometimes is not a good ground source, so that difference of potential of the ground and the equipment seems even more hazzardous.

I also have another question, for you or anyone that might reads this thread.

Has anyone ever heard of a fataliity or injury that was a result of a grounded line becoming energized by a different source, such as transmission, or another primary source?

barehander
03-15-2008, 12:20 PM
Quote:
Originally Posted by johnbellamy http://www.powerlineman.com/lforum/images/buttons/viewpost.gif (http://www.powerlineman.com/lforum/showthread.php?p=41520#post41520)
So I don't glove anything over 5kv, (un less, sometimes, I not going to tell you I have'nt.) Transmission I have worked hot, 69kv,115kv,and 230kv, nothing higher.

#1...We have alot of tree damage on 115, and 69kv, what I have done on a isolated piece of a 115kv loop, is close the ground switch on one end, (if available)at the site, identify and test the short the three wires out, then do my repairs, allways macking any broken connductor and never cutting the wire to splice without doing the same, I never ware rubber gloves, just leathers and have never had a problem for the last 11 years.



First of all, grounding is the most mis-understood tool that a lineman has. All you have to do is read this thread & the link I posted here to see all the ways people do it. OldLineman & a few others understand about placing everything at the same potential. There is step and touch potentials, the introduction of foreign grounds at a location, such as phone messenger, cable TV, guy wires, etc. Most Lineman do not know what the fault duties of the lines they work on. They do not understand about grounding for the fault duties of the Transmission lines that cross over the lines they are working on, just in case the Transmission drops onto their line. Most Lineman do not know, for example, that if you have a line coming out of a Sub. that has a fault duty of 35,000amps, how many miles of line does it take before the fault duty falls below 15,000amps.
I have the answers for your questions, but, and I'm not picking on you, I just want everyone to know how much danger is present in what you say you do.

First off, here are some of our rules.....
Grounds will be visible to at least one member of the crew at all times...
Before grounding, the cond. will be cleaned to remove oxidation and grease will be applied.
You will short the cond. first, then apply the ground.

Where I work, all of the ground switches have been removed due to human error problems and maintenance issues. Remember that it's just a blade that goes into a catch, that may be very corroded. Could have a lot of resistance......

Here's the scenario....
You are working on a 115kv loop, from a Sub. to an open switch. You have your ground switch closed. Lets say the section is 2 miles long. Lets also say that between you and the Sub. another 115kv line crosses under yours. Lets also say that you are in a metal basket attached to a metal boom truck. As you said, you shunt the cond. together and go to work....
At sometime during the job, a truck hits a pole somewhere between you and the Sub. breaking all 3 wires on the Sub. side of the pole, but only breaking 1 wire on your job side of the pole and it drops down into the other line.
Your station ground has been eliminated and even though only 1 wire is touching the other line, all 3 of your cond, are energized @ 115kv (because they are tied together) and because you have no ground @ your work site, and your truck is not tied to the EPZ, you have now become a human fuse.
You are DEAD!

I admit this may never happen, as you said about yourself in 11 yrs, but....

I never thought it would happen to me in my 35yrs of linework but it did just 2 mo. ago.....a set of Distribution grounds energized at 70kv in a bracket ground scheme with a set of Trans. & dist grounds attached to the same rod 2 miles away. It relayed the circuit, but it went 2 miles at the speed of lite. I'm very lucky I can still type...................

Think about this stuff....

johnbellamy
03-15-2008, 01:19 PM
Quote:
Originally Posted by johnbellamy http://www.powerlineman.com/lforum/images/buttons/viewpost.gif (http://www.powerlineman.com/lforum/showthread.php?p=41520#post41520)
So I don't glove anything over 5kv, (un less, sometimes, I not going to tell you I have'nt.) Transmission I have worked hot, 69kv,115kv,and 230kv, nothing higher.

#1...We have alot of tree damage on 115, and 69kv, what I have done on a isolated piece of a 115kv loop, is close the ground switch on one end, (if available)at the site, identify and test the short the three wires out, then do my repairs, allways macking any broken connductor and never cutting the wire to splice without doing the same, I never ware rubber gloves, just leathers and have never had a problem for the last 11 years.



First of all, grounding is the most mis-understood tool that a lineman has. All you have to do is read this thread & the link I posted here to see all the ways people do it. OldLineman & a few others understand about placing everything at the same potential. There is step and touch potentials, the introduction of foreign grounds at a location, such as phone messenger, cable TV, guy wires, etc. Most Lineman do not know what the fault duties of the lines they work on. They do not understand about grounding for the fault duties of the Transmission lines that cross over the lines they are working on, just in case the Transmission drops onto their line. Most Lineman do not know, for example, that if you have a line coming out of a Sub. that has a fault duty of 35,000amps, how many miles of line does it take before the fault duty falls below 15,000amps.
I have the answers for your questions, but, and I'm not picking on you, I just want everyone to know how much danger is present in what you say you do.

First off, here are some of our rules.....
Grounds will be visible to at least one member of the crew at all times...
Before grounding, the cond. will be cleaned to remove oxidation and grease will be applied.
You will short the cond. first, then apply the ground.

Where I work, all of the ground switches have been removed due to human error problems and maintenance issues. Remember that it's just a blade that goes into a catch, that may be very corroded. Could have a lot of resistance......

Here's the scenario....
You are working on a 115kv loop, from a Sub. to an open switch. You have your ground switch closed. Lets say the section is 2 miles long. Lets also say that between you and the Sub. another 115kv line crosses under yours. Lets also say that you are in a metal basket attached to a metal boom truck. As you said, you shunt the cond. together and go to work....
At sometime during the job, a truck hits a pole somewhere between you and the Sub. breaking all 3 wires on the Sub. side of the pole, but only breaking 1 wire on your job side of the pole and it drops down into the other line.
Your station ground has been eliminated and even though only 1 wire is touching the other line, all 3 of your cond, are energized @ 115kv (because they are tied together) and because you have no ground @ your work site, and your truck is not tied to the EPZ, you have now become a human fuse.
You are DEAD!

I admit this may never happen, as you said about yourself in 11 yrs, but....

I never thought it would happen to me in my 35yrs of linework but it did just 2 mo. ago.....a set of Distribution grounds energized at 70kv in a bracket ground scheme with a set of Trans. & dist grounds attached to the same rod 2 miles away. It relayed the circuit, but it went 2 miles at the speed of lite. I'm very lucky I can still type...................

Think about this stuff....

But I can't put every sinero of what could happen, I believe I work safe, and try to work smart and apply what I have learned to a situation that might be different, to me thats a big part of what being a journeyman is.

I have a hard time working with guys that dwell on all the things that could happen. All I can do in situation I don't really understand is maintain my work practices and clearaces, and sometimes just say "let er buck", but like I have stated before, I put my ass in the bite and nobody elses. I don't know any other way, the lights have to stay on.

I have a hard time understanding wording in books, or listening to guys who can do stuff on paper, but have no practcal work experience. I appriciate talking with experienced hands because they actually do the work, and like I have stated before, there is alot out there I have not been exposed too, 35 years is alot, I trust what you have to say because you speak from experiance, not just books. Thanks

lewy
03-15-2008, 01:38 PM
I'm getting ready to go to the central coast of Ca. for the weekend (best wine in the world) and I wanted to ask this question of you and others that might answer your question.
Lets say you have a 115kv switch and you needed to Phase across it for some reason and all you had was a 12kv phasing set.
How would you do it?Before I answer are you asking to phase check across an open switch or checking the integrity of your insulators?
By macking do you mean jumpering out? a term I have never heard before.
Your example is good reason for EPG & why all steel in the air should be grounded & at the same potential.

BigClive
03-15-2008, 01:57 PM
People have said use your rubber gloves, but when you put them on, you get ate up , feels like needles jumpin back and forth between the rubbers and you bare skin.


What actually happens there is the glove forms a dielectric barrier but current still transfers to your hand capacitively. On each half wave the current transfers back and forth and whereas without the glove it would be a single fat spark, the dielectric effect turns it into a mass of tiny sparks creating areas of corona discharge through the air in your glove. It does indeed feel like lots of tiny needles prickling your hand. This is the principle of a vintage piece of quack medical equipment called a violet ray or violet wand. It's basically a high voltage transformer (an Oudin coil to be precise) with a hollow glass electrode with a vacuum drawn in it. the name violet ray comes from the purple glow from the vacuum in the electrode. The effect is to shower lots of tiny sparks onto the surface of your skin when the electrode is brought close. It was sold as a miracle cure-all in the early days of electricity, and the claims included curing infertility, cancer and baldness.

One genuine medical effect it had was the production of ozone on the surface of your skin due to the corona discharge. This sterilised the area it was applied to.

The prickling sensation isn't bad but it would be annoying with continuous contact. The gloves would certainly smell fresh afterwards due to ozones bleaching effect!

barehander
03-15-2008, 02:36 PM
Before I answer are you asking to phase check across an open switch or checking the integrity of your insulators?
By macking do you mean jumpering out? a term I have never heard before.
Your example is good reason for EPG & why all steel in the air should be grounded & at the same potential.

Yes...
just wanted to show how much leakage there is.....

barehander
03-15-2008, 02:40 PM
But I can't put every sinero of what could happen, I believe I work safe, and try to work smart and apply what I have learned to a situation that might be different, to me thats a big part of what being a journeyman is.

I have a hard time working with guys that dwell on all the things that could happen. All I can do in situation I don't really understand is maintain my work practices and clearaces, and sometimes just say "let er buck", but like I have stated before, I put my ass in the bite and nobody elses. I don't know any other way, the lights have to stay on.

I have a hard time understanding wording in books, or listening to guys who can do stuff on paper, but have no practcal work experience. I appriciate talking with experienced hands because they actually do the work, and like I have stated before, there is alot out there I have not been exposed too, 35 years is alot, I trust what you have to say because you speak from experiance, not just books. Thanks

Why else would you ground? It happened to me, so it could happen to you.
What I was trying to say is that if you don't add that ground and just shunt, it could happen to you, and "let it buck" could be on your tombstone.........

lewy
03-15-2008, 02:55 PM
Yes...
just wanted to show how much leakage there is.....

Well I am still not sure if this is what you meant, but on glass bells if you potential check accross each insulator & get 0 you know that that particular insulator has failed, you should get something accross each insulator & the value would obviously be lower as you get closer to the structure.

Nate
03-15-2008, 03:28 PM
We all know that induction exists, But at our utility we have never really measured how much voltage gets induced onto a line. Recently we had 5 arresters blow on a line that is only 2 spans of overhead 3 phase wire. Feed from a riser and dead-ending at a 3 phase delta bank. We blew 4 arresters in about 1 hour. We ended up de-energizing the B phase and C phase line (leaving A hot). We then decided to check the B and C phase for voltage to see it A phase was tracking onto the ground and shorting the arresters. When we checked there was 2000V on B phase and 1500V on C phase. It was a sunny day with no humidity. Through other testing we found this to be seperate from the arresters blowing and it was simply induction. We were taken back by the amount of voltage that was being induced... So please remember it is not dead until it is grounded.

Just wondering how long of a run is the underground to the dip pole?

Nate
03-15-2008, 03:52 PM
If you have induction on your line the only way to control it is to ground the line just by testing will not drain it, only the the grounds will & once you remove the grounds it will be back. That is part of the reason our province brought in a new rule that when you are working on a line it will either be grounded or energized no more working on isolated primary.

We bleed off induction at my company by using a Chance phasing set the 15 or 40 kv set that has the cord between the meter side and the other end.
We do this on our 600 amp system before we unbolt T Bodies off feeder switches. First we use our capacitance tester to check deenergized then we remove the arresters then we take the Chance tester hook the pig tail on the ground the insert the bushing adapter into the bushing, the meter will read any where from 5 to 15 kv when first inserterd you can watch the needle go back down to zero, after all three phases have been bled off we then install an elbow ground and the snap ground each cable on the switch.
after that we rubber up and remove them from the switch and then install grounds to work the other end. I guess im getting at long runs of any underground always have a lot of induction on them and that my have added to your problem also.

lewy
03-15-2008, 04:29 PM
We bleed off induction at my company by using a Chance phasing set the 15 or 40 kv set that has the cord between the meter side and the other end.
We do this on our 600 amp system before we unbolt T Bodies off feeder switches. First we use our capacitance tester to check deenergized then we remove the arresters then we take the Chance tester hook the pig tail on the ground the insert the bushing adapter into the bushing, the meter will read any where from 5 to 15 kv when first inserterd you can watch the needle go back down to zero, after all three phases have been bled off we then install an elbow ground and the snap ground each cable on the switch.
after that we rubber up and remove them from the switch and then install grounds to work the other end. I guess im getting at long runs of any underground always have a lot of induction on them and that my have added to your problem also.On an isolated primary U.G. cable there will be a charge on the cable, this is different than induction & yes you can bleed it off with your tester, but you would as you said still ground the cable before doing any hands on work.

wtdoor67
03-15-2008, 06:35 PM
has become a little tangled in my opinion, but I don't mind. I like things a little jangled.

The first poster was talking about induction and mixing it up with ferroresonance. Well we got that sorted out, I think.

Then the subject became the grounding of lines and EPZ grounding and I think the jury is still pondering that subject.

Then it became the phasing of a 115 line with a 12 KV phasing set. Never got that one. Must have missed something. Thought maybe there was some kind of trick or something.

One poster (Barehander) inferred that each particular piece of line can be calculated as far as fault current and other factors that might be
determined could be made to indicate the type or method of grounding that might be determined. This would include all the different voltages that might perhaps accidently come into contact with the line you are working on etc. I am no expert but I have worked on a fair number of transmission lines with several different entities and have never encountered a plan or guide that would indicate all the different fault currents and other technical aspects that would govern what you might be exposed to on storm breaks etc. There can be of course a myriad of different transmission voltages etc. on any storm break. If this is a recurring problem I expect OSHA better get on it.

The latter postings concern underground. One person asked about the amount of URD feeding the upfeed dip that fed the overhead going to the delta connected bank. From my experience the closing of the underground dips would not cause the blowing of the arresters. The arresters blew because when the dips were closed this caused ferroresonance because the 3 pot delta bank was closed at the time. And yes anytime an insulated,ungrounded conductor sets in the open air it may pick up induction.

Also a piece of ungrounded URD wire with no grounds or load on it can sometimes act like a capacitor and it will bite your butt if you touch it with your bare hand without first grounding it.

Working once and some guys were skinning some URD that held a charge. One guy remarked. "You know that shit will hold a charge?" Damned if one of the guys standing there didn't thereupon touch it and got the crap knocked out of him. Everyone had a good laugh.

BigClive
03-15-2008, 10:09 PM
has become a little tangled in my opinion, but I don't mind. I like things a little jangled.

Then it became the phasing of a 115 line with a 12 KV phasing set. Never got that one. Must have missed something. Thought maybe there was some kind of trick or something.


I think the idea was that the tester was hooked to one side of the switch then the other lead touched to insulator bells starting as far away from the other side of the switch as possible and moving closer until leakage allowed the tester to work.

Since a 12kV tester would not have an insulation rating for even having one of it's terminals on 115kV I'm not sure I'd endorse that. The wireless phaser on the other hand sounds an excellent gadget.

wtdoor67
03-16-2008, 08:40 AM
All 12 KV testers I have used, I don't believe I would try that.

lewy
03-16-2008, 09:06 AM
A little off topic, but anytime we do maintenance on our 44kv airbrake switches 1 of the things we have to do is test the dead end insulators if they are glass bells (they are mostly polymer now) & we do this with our phasing sticks
Like I said earlier you should get a reading across each individual bell if you get 0 it means that particular bell is defective.

"little beaver"
03-16-2008, 10:56 AM
Before I answer are you asking to phase check across an open switch or checking the integrity of your insulators?
By macking do you mean jumpering out? a term I have never heard before.
Your example is good reason for EPG & why all steel in the air should be grounded & at the same potential.

"MACKING IT OUT" is one of those stupid terms that your hear once in a while in the business. How many on here know what that term derives from??

Another, is "GROUND CHAINS". A guy was talking about GROUND CHAINS a couple of weeks ago at the Hot stick testing Lab. I asked him what he met(sic)? He said he knew it didn't make sense, he just was repeating what he heard others say. I explained to him where that term comes from.

GROUND CHAINS even date me and I've been around the business 40 yrs in May. However, I know where it comes from 'cause my Dad told me about using GROUND CHAINS!

johnbellamy
03-16-2008, 12:14 PM
We use machanical jumpers, "Macks" to jumper things out, so if you think that is a "stupid term" well I don't like my terminology I use and the guys I work with use called "Stupid" that is not a vary nice word.

Orgnizdlbr
03-16-2008, 12:31 PM
We use machanical jumpers, "Macks" to jumper things out, so if you think that is a "stupid term" well I don't like my terminology I use and the guys I work with use called "Stupid" that is not a vary nice word.

The term may seem "stupid" to some, it means just what John said. It isnt a stupid term where I come from.......

"little beaver"
03-16-2008, 12:41 PM
We use machanical jumpers, "Macks" to jumper things out, so if you think that is a "stupid term" well I don't like my terminology I use and the guys I work with use called "Stupid" that is not a vary nice word.

OK John. I apologise if you think that I called you or your fellows, stupid. I didn't, I just always thought the term was 'stupid'(still do by the way). BTW: That's what 'discourages" me from posting on here is that people continually take inferance from things that are not meant that way. However, I quess that's the nature of the internet.

Well, you got in half right. Again, I asked my Dad many years ago what was meant by a 'mack' and it's comes from 'mechanical' jumper as opposed to an 'automatic' jumper. Now, has anyone on here ever seen or used an 'automatic' jumper?

I've never used one as they were already outlawed by my time in the late 60's. But, I did see one when I was an App and it was explained to us why they were no longer in use. They were made to pick up load. What would happen of course was that someone would try to break load with them. They weren't made for that and people got hurt. Also, they would think they were closed and they would still be open and there you were on 4KV with a big ball of fire in your face. So that was the end of 'automaitc jumpers'.

Orgnizdlbr
03-16-2008, 12:52 PM
Have used and still use "pickup jumpers" they're not outlawed here. The contact portion of the jumper is clear plastic so you cant mistake whether its open or not. No way shape or form are they used to break load, they are made to pickup load, not break it.......

wtdoor67
03-16-2008, 03:12 PM
You Canucks don't get offended but you need to get out of your little box. I'm sure most will agree with me on this matter. You guys forget that a large part of the world also does this type of work. You remind me of 2 county boomers. I have worked around a lot of people from a cross section of the U.S. and a few Canucks. Many of them used different terms for hardware and tools. Underslungs-Underarm Disconnects, Pots-Cans, Grips-Porkchops, Cumalongs-Hoists, Jackline-Slackblocks etc.etc. Mack is a very common term for a mechanical jumper and yes, pickup jumpers are as common as flies in the good old USA. Try to avoid that old cliche. "This is the way we've always done it."

P.S. Anyone who would try to use a pick up jumper to break load is not playing with a full deck.

And yes while I'm at it, do not use your co's term or regional term for a piece of hardware or tool. REC guys seem to think that every one knows what an A1 or an A2 is. Not everyone has worked for an REC. Use generic terminology. Single phase tengent, single phase DE, etc. etc. Also the terminology for different co's acronyms are very similar. PP&L could be Philadelphia Power and Light, Pennsylvania Power and Light or maybe even Pacific Power and Light. Savvy?

johnbellamy
03-16-2008, 03:15 PM
We have a temp. cutout, you hang it on the source with a shotgun, the bottom has a tee bracket where you hang your mack, to the load side.

We can make load or break load with a loadbust tool. It is a 2 man operation, one guy holds the other part of the tee bracket to secure it while the other opens or closes it.

A B Chance is the brand, I don't know the cost. It is a good tool and easy to use, since we are not aloud to make or break load with a hot tap anymore.

BigClive
03-16-2008, 06:45 PM
GROUND CHAINS even date me and I've been around the business 40 yrs in May. However, I know where it comes from 'cause my Dad told me about using GROUND CHAINS!

Ground chains? Surely not an actual chain? From past experiments I know that chain is a very unreliable conductor due to the sheer number of loose contacts along the length.

barehander
03-17-2008, 10:37 PM
We all know that induction exists, But at our utility we have never really measured how much voltage gets induced onto a line. Recently we had 5 arresters blow on a line that is only 2 spans of overhead 3 phase wire. Feed from a riser and dead-ending at a 3 phase delta bank. We blew 4 arresters in about 1 hour. We ended up de-energizing the B phase and C phase line (leaving A hot). We then decided to check the B and C phase for voltage to see it A phase was tracking onto the ground and shorting the arresters. When we checked there was 2000V on B phase and 1500V on C phase. It was a sunny day with no humidity. Through other testing we found this to be seperate from the arresters blowing and it was simply induction. We were taken back by the amount of voltage that was being induced... So please remember it is not dead until it is grounded.
The original post...

My company does test induction, usually after a death. Mostly after a Lineman touched an ungrounded line, and some voltages have been around 4kv in Trans. corridors.
One story that demonstrates how dangerous induction and grounding is one where a crew was working on a 3 pole 70kv double deadend structure with guys and anchors ahead and behind. It was attached to a 230kv twr line that ran for miles before it dropped off onto wood poles. They had to change all the anchors so they installed a driven ground rod 2' form 1 of the anchors and when the groundman was in the process of repulling the guy at the anchor near the ground rod, he laid the hoist onto the ground rod to move the grip, still holding the grip, he reached down to pick up the hoist off the rod. The guy on the other side of the pole was made up (no bobs) to a new anchor on the other side. One less Lineworker today.....
The difference of potential was over 3kv.....

Quote:
wtdoor67: has become a little tangled in my opinion, but I don't mind. I like things a little jangled.

The first poster was talking about induction and mixing it up with ferroresonance. Well we got that sorted out, I think.

Then the subject became the grounding of lines and EPZ grounding and I think the jury is still pondering that subject.

Then it became the phasing of a 115 line with a 12 KV phasing set. Never got that one. Must have missed something. Thought maybe there was some kind of trick or something.

One poster (Barehander) inferred that each particular piece of line can be calculated as far as fault current and other factors that might be
determined could be made to indicate the type or method of grounding that might be determined. This would include all the different voltages that might perhaps accidently come into contact with the line you are working on etc. I am no expert but I have worked on a fair number of transmission lines with several different entities and have never encountered a plan or guide that would indicate all the different fault currents and other technical aspects that would govern what you might be exposed to on storm breaks etc. There can be of course a myriad of different transmission voltages etc. on any storm break. If this is a recurring problem I expect OSHA better get on it.

I've been around this site for a "few yrs" and things do move around in threads. I'm going to use a term from your keyboard, 2 county boomer...Ghostdog asked about induction and grounding, 1st post.
Mr Bellamy asked about getting the crap knocked out of him on 115kv hardware. Used to be able to phase Trans. by starting at the first bell and going out till you got a reading, and yes, can't do that anymore. What I was trying to point out was that it could be insulator leakage onto that arm.
Mr Bellamy also stated that he worked on line, trusting a ground switch at a sub. who knows how far away and only shunted the wires together. I was also pointing out how dangerous that was by giving an example.
I've had to defend myself many times here, so here goes.....
Where I work, I have a grounding manual that addresses every situation that can happen. From broken wire conditions, to boring to pull in underground. I have to count grounds installed, and removed, and report that to operations. I also have access to every fault duty, of every sub, of every voltage. I have charts to tell me how far away the fault duties fall below 15,000amps, or 30,000amps. I have to fill out a form that states all of the above and more. Where my yard is, (in a sub) there are fault duties over 106,000amps and if you go out & hang 2/0 grounds, and something happens, the grounds and you will be gone.
I really don't care how may counties some one has worked, if someone learns something here, it's a good thing.
I almost got killed by someone energizing my Dist. grounds @ 70kv so I've had a bad year so far...and I think I need a beer!
Sorry for the long one, but if you've never seen a brother die from stupidity, by themselves or at the hands of others.........it' a hard lesson!

barehander
03-17-2008, 10:42 PM
A little off topic, but anytime we do maintenance on our 44kv airbrake switches 1 of the things we have to do is test the dead end insulators if they are glass bells (they are mostly polymer now) & we do this with our phasing sticks
Like I said earlier you should get a reading across each individual bell if you get 0 it means that particular bell is defective.

Lewy.......this is what we use...
http://www.hdelectriccompany.com/it4.htm

Question? Why do you have to test them?

BigClive
03-18-2008, 08:37 AM
That unit's basically a "megger" (insulation tester) for insulators.

I guess the main need to test older insulators is to see if they are breaking down over time. If more and more bells progressively failed in an insulator I guess it could lead to an avalanche tracking effect that could see the whole insulator fail dramatically. If it failed physically, then it could damage the line too.

I guess that unit will also show a build up of conductive dirt on an insulator too.

lewy
03-18-2008, 03:46 PM
Lewy.......this is what we use...
http://www.hdelectriccompany.com/it4.htm

Question? Why do you have to test them?

It is 1 of the things we check when we do our 44 kv air brake switch maintenance.
like I said if you had 0 across 1 of the bells it would mean that bell is not doing its job (there should be a difference of potential across each bell) & we would replace them all with a polymer, but again most of our deadend insulators are polymer & this test only works on glass
we just use either our chance or hastings phasing sticks

wtdoor67
03-18-2008, 05:42 PM
is my last post on this thread. I will attempt to explain my comments.

My comment on 2 country boomers was directed toward the Canucks. I have always found the term Macks for Mechanical Jumpers to be very logical, and have never found anyone who didn't understand it. Grounding chains were the first type of grounding device used on de-energized lines as far as I know and the term just carried on. I have never heard it used except for very old hands.

The comments about EPZ grounding just came from working in the AEP system these last few years before I retired. It seems ever 6 months they changed their minds on grounding and when they finally settled on EPZ, then it wasn't a short time until they stated at several safety meetings that it was no longer valid simply because the potential of your hooks could not match the potential of the bracket around the pole. They finally stated that we should do EPZ and wear rubber gloves until they made a decision . As the last of my knowledge they had not made up their minds.

The phasing across phases of a 115 Kv line, with a 12 KV phasing set gave me the impression that this could be done some way in order to determine correct phasing. I think this was actually meant to determine bad insulators.

I have never experienced on routine work or on storm breaks a briefing or notification of the amount of fault current that might be encountered on a particular line. I expect PG&E has taken this on themselves as a little better safety method. I think it is a good thing that perhaps needs to be passed on.

Induction is very dangerous and I have always been surprised that more information is not given out concerning it. I worked with a guy once who was rendered unconscious when he was exposed to some on a 115 Kv line. I have seen several people zapped by it when it was most obvious that it was probably present.

As far as load pickup jumpers,I have probably never seen a crew that didn't have one. And for you Canucks. They now make a load break jumper and have for some time. Maybe y'all need to purchase some. They are rather pricey.

Stinger
03-23-2008, 11:14 AM
Hey guys, let me give you a live real sceniro we had the other day. As it was discussed by JL's, Frm, & GF's. The differnt answers were interesting. We are pulling in new wire with old wire on 115kv. It is adjacent to a hot 115. It crosses three distro line 13.8 3o and 2 7.2 kv 1o all covered and guard poles installed at their crossings. All proper grounding is in place at the puller, tensioner and distro crossings for the pull. the pull is 16000 ft 795 acsr. They run a final check of the line before the pull to ensure all masters have been taken off. Low and behold they discover two structures still clipped in that has to be done of hooks. A set of masters are installed a crew goes to it off ladders. ( wood H structures ). There are masters at both the subs and the jumpers have been cut on the first d/e out of the subs also have our masters. This line does not cross any other transmission line, just a few distro lines here and there. While the crew is unclipping they notice a sleeve in the line we are going to pull. No way to get to it because of row conditions. It is determine that the phase can be lowered safely to the ground without making any incidental contact with the three coverd and guarded disto line. We decided that we could lower the phase and cut the sleeve and put back to back socks on. We have the ladder crew remove the ground being lowered and then have them reconnect the ground when we have it at working level. Then we will put another set of master on the other H frame. Our thinking is we now have two sets of masters and we are working between visible master grounds. We then use a stick and put on a jumper so we can cut out the sleeve and put the socks on. The issue that arose was we can not do it if we do not have a grounding mat. Some say yes we can because we have the line at equal potential, other say no, because now there is step touch potential. It got to be a rahter heated discussion. I usally wear hot shoes on transmission jobs. I would have felt safe, other say they would not. Our grounding book and safety book and the NJATC book are in somewhat conflict of one another. Please give me some feed back and opinions on this. Thanks brothers.

wtdoor67
03-23-2008, 06:39 PM
Seems like you have several options covered. I would think wearing rubber gloves would suffice, if they're rated for the distribution voltages you are guarding against. On the 115 Kv, I don't know.

What is the spacing on the H fixtures on the 115 Kv? Why would you have to use ladders to put the wires in stringing dollies? All of it I ever worked on was rather narrow spacing on tangent structures.

old lineman
03-23-2008, 09:13 PM
Likely you would not have had enough potential difference to cause you much more than unpleasant pokes during the process if all went as planned.
However, you must go back to the purpose of installing grounds in the first place.
It's proof positive that your on the right circuit.
It is intended to drain off any induction that could be present and you should look back on this subject to see that the grounds for adequate reduction of induced voltage are to be at the point of work.
Grounds are always to serve another purpose, and that is to ensure rapid isolation should the circuit become inadvertently re-energized.
That's why the discussion on the fault current levels that are available.
Depending on the levels available the size of the grounding cables can be determined.
If we ground for the unexpected and rare event where the circuit becomes re-energized how well do you think you were protected standing on the ground working on grounded conductors that WILL become momentarily energized to the offending circuits voltage level.
Standing on the ground ensures that you will become a parallel path to ground.
The only way to positively protect yourself against all possible situations would be to lay down a conductive mat and connect it directly to the conductor.
The cables don't need to be large because all your trying to do is ensure that there is no potential difference between your feet and hands.
No potential difference , no possibility of an electrical shock.
The Old Lineman