Greater than 7.2kv URD

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Greater than 7.2kv URD

Post  rcdallas on Tue Feb 14, 2012 2:10 am

As far as 7200/12470 underground goes that's all I've played with. Every now and then I'll hear some people talking about wait to your first experience with 14.4/24.9 or 19.9/34.5 underground.

What is it that you run into that is more of a problem/hazard/things you really need to watch out for with on greater voltages? Will a slightly dirty well insert give you more hell when going home with it? Feel/hear the tickler drain wire pretty good?

There's gotta be something that more unforgiving when working higher voltages in underground besides bigger elbows and wire, etc.

More of a pain to fault locate with?

Anyone?



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Re: Greater than 7.2kv URD

Post  MI-Lineman on Tue Feb 14, 2012 7:24 pm

GROUNDS!! I've seen new 14.4 cabinets fail (polly insulators flash over) cuz they (the cabinet) were changed at one time but not the ground rods!! You know how the rods eventually corrode away to nothing more than a spear about a foot in the ground! You may never notice this on our 4.8 cabinets! I try to tell guys if ya got the cabinet off DRIVE NEW RODS!! It's only your life depending on those ground rods at a later time during an outage while you're leather gloving!!

Dirt and weeds, see a lot of dirty cabinets and weeds that have flashed over!!

Me, I would never touch the outside of a 14.4 cabinet after some of the sh!t I've seen!

As for the conductor itself I can't think of any abnormal or unusual conditions do to the higher voltages?

Wish Cowboy would sign up! He'd have a few I bet!
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Re: Greater than 7.2kv URD

Post  lamartin.cvec on Tue Feb 14, 2012 11:13 pm

rcdallas wrote:As far as 7200/12470 underground goes that's all I've played with. Every now and then I'll hear some people talking about wait to your first experience with 14.4/24.9 or 19.9/34.5 underground.

What is it that you run into that is more of a problem/hazard/things you really need to watch out for with on greater voltages? Will a slightly dirty well insert give you more hell when going home with it? Feel/hear the tickler drain wire pretty good?

There's gotta be something that more unforgiving when working higher voltages in underground besides bigger elbows and wire, etc.

More of a pain to fault locate with?

Anyone?



Flash over. Usually due to Partial Vacuum. It seems that the early generations of Bushing inserts were made as straight plugs and the probes in earlier generations were solid (no porcelain tip for "load break". these 2 factors would come into play with several flash over events. Eventually lineman would start figuring things out and manufacturing would work around these things. Most inserts now are ribbed (its valentines day) for her pleasure--this allows for the displacement of the partial vacuum that would cause flash over and eventually (again valentines day) porcelain tips where added for load break.

I hate switch in some of our 3phase ug pots that our DV it seems that most of them are smaller is size and structure and when equipped with the larger 25kv hard ware allow for less switching room. Not really a problem but a pain in the but when it's cut over from 12.4 to 24.9.

Another problem is that some company's still switch UG early morning or late evenings when the businesses they serve or not operating. That ok if your using an actual SF6 switch but doing it in a padmount with elbows can again cause flash over-- you should NOT switch under any kind of condition with high humity/dew/rain with elbows.

Lastly most of our 7.2 is plug and play elbow stuff we have a few bolt on switches. When you get into our 25 kv stuff, well then your talking about 200 amp elbow that are plug and play as well as 300 amp 4/0 and 600 amp 500mcm elbows. The latter 2 are bolt on stlye. If you don't have your system set up in a net work or "loop feed" there gonna be some big outages in order to switch.

with bolt on elbows you have to switch "Dead" It's the nature of the beast and 500 ain't real friendly on the end of a shotgun stick.

I have some more input on this but I'd rather not thing of UG right now... kids are in bed time to go see momma!

Work Safely,

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Re: Greater than 7.2kv URD

Post  MI-Lineman on Wed Feb 15, 2012 12:17 am

Oh yeah, good one Martin I almost forgot the whole "loadbreak" issue but most of ours is corrected now or at least we know not to switch nonloadbreaks!
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Re: Greater than 7.2kv URD

Post  Highplains Drifter on Wed Feb 15, 2012 12:48 am

The insulation is some what thicker with high voltages, some utilities that experience below zero temptatures will remove up to 12 foot of the jacket to make handling the cables some what easier during switching.
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Re: Greater than 7.2kv URD

Post  rcdallas on Wed Feb 15, 2012 1:24 am

MI-Lineman wrote:GROUNDS!! I've seen new 14.4 cabinets fail (polly insulators flash over) cuz they (the cabinet) were changed at one time but not the ground rods!! You know how the rods eventually corrode away to nothing more than a spear about a foot in the ground! You may never notice this on our 4.8 cabinets! I try to tell guys if ya got the cabinet off DRIVE NEW RODS!! It's only your life depending on those ground rods at a later time during an outage while you're leather gloving!!

Dirt and weeds, see a lot of dirty cabinets and weeds that have flashed over!!

Me, I would never touch the outside of a 14.4 cabinet after some of the sh!t I've seen!

As for the conductor itself I can't think of any abnormal or unusual conditions do to the higher voltages?

Wish Cowboy would sign up! He'd have a few I bet!

The soil conditions must be pretty acidic over there in the great north...where I came up driving a ground rod was pretty much useless; sand! Where I'm at now there is a ton of salt in the soil eating direct bury alive.

I'm glad you mentioned it; now I'm just going to have to be more aware of it now that you mentioned it.

This is more problematic on 14.4 and above as far as ground rods or you just saying?

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Re: Greater than 7.2kv URD

Post  rcdallas on Wed Feb 15, 2012 1:34 am

lamartin.cvec wrote:
Flash over. Usually due to Partial Vacuum. It seems that the early generations of Bushing inserts were made as straight plugs and the probes in earlier generations were solid (no porcelain tip for "load break". these 2 factors would come into play with several flash over events. Eventually lineman would start figuring things out and manufacturing would work around these things. Most inserts now are ribbed (its valentines day) for her pleasure--this allows for the displacement of the partial vacuum that would cause flash over and eventually (again valentines day) porcelain tips where added for load break.

I hate switch in some of our 3phase ug pots that our DV it seems that most of them are smaller is size and structure and when equipped with the larger 25kv hard ware allow for less switching room. Not really a problem but a pain in the but when it's cut over from 12.4 to 24.9.

Another problem is that some company's still switch UG early morning or late evenings when the businesses they serve or not operating. That ok if your using an actual SF6 switch but doing it in a padmount with elbows can again cause flash over-- you should NOT switch under any kind of condition with high humity/dew/rain with elbows.

Lastly most of our 7.2 is plug and play elbow stuff we have a few bolt on switches. When you get into our 25 kv stuff, well then your talking about 200 amp elbow that are plug and play as well as 300 amp 4/0 and 600 amp 500mcm elbows. The latter 2 are bolt on stlye. If you don't have your system set up in a net work or "loop feed" there gonna be some big outages in order to switch.

with bolt on elbows you have to switch "Dead" It's the nature of the beast and 500 ain't real friendly on the end of a shotgun stick.


So one of the big problems is just the bigger wire size not being as agile; I've seen that not to long ago where some 1000mcm was pulled in direct from the sub to feed an industrial customer 7200 but using 25kv cable. I had move some elbows and it's not to giving in flexibility.

So it's going to have more of a tendency to track and stuff; in other words no time to diddle daddle go home with it, period.

It's funny you mentioned switching in the rain and stuff it was just a few months ago where I had to switch in a padmount during the rain and when I opened the lid nobody plugged the insert; I was livid. All I could think is man the conditions are right.

What are your thoughts on putting the tickler wire around the insert and the bushing well? I was brought up to always put one there. Now I wonder how much it could hit the fan on some 25kv if it didn't have it.

Yeah I hear you on the bolt on, that's definitely not anything you do hot. We have that in around the mall and downtown stuff, t-bodies, etc.

When you get time; NEED INPUT. geek

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Re: Greater than 7.2kv URD

Post  rcdallas on Wed Feb 15, 2012 1:37 am

Highplains Drifter wrote:The insulation is some what thicker with high voltages, some utilities that experience below zero temptatures will remove up to 12 foot of the jacket to make handling the cables some what easier during switching.

12' ?!?! I haven't made up a splice in sub zero weather and I don't even want to think about it. Last elbow I made up it was probably around 35 degrees and I didn't like stripping the semi-con then Angry Smiley

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Re: Greater than 7.2kv URD

Post  lamartin.cvec on Wed Feb 15, 2012 9:00 pm

So one of the big problems is just the bigger wire size not being as agile; I've seen that not to long ago where some 1000mcm was pulled in direct from the sub to feed an industrial customer 7200 but using 25kv cable. I had move some elbows and it's not to giving in flexibility.

So it's going to have more of a tendency to track and stuff; in other words no time to diddle daddle go home with it, period.

It's funny you mentioned switching in the rain and stuff it was just a few months ago where I had to switch in a padmount during the rain and when I opened the lid nobody plugged the insert; I was livid. All I could think is man the conditions are right.

What are your thoughts on putting the tickler wire around the insert and the bushing well? I was brought up to always put one there. Now I wonder how much it could hit the fan on some 25kv if it didn't have it.

Yeah I hear you on the bolt on, that's definitely not anything you do hot. We have that in around the mall and downtown stuff, t-bodies, etc.

When you get time; NEED INPUT. geek [/quote]

Absolutely add the static/bleeder wire to the inserts, elbows , and arresters. At higher voltages they will break down as they build up induction and it snaps over to the can trying to bleed it's self off. Also be aware of the drip cup for the bayonet fuse--DO NOT let the tx oil drip on the inserts--oil and inserts do not play well together the oil will cause the inserts to rupture and break down.

T-bodies are not allowed here and with good reason:they are junk. If you need a tbody then you really need a junction/switching point or the route of the line needs to be redesigned.

As for the million? sounds like you need to cut over some line to 24.9/14.4 drop some amps and lower some wire size. Gotta love engineering.

Work safely,

L.A.Martin
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Re: Greater than 7.2kv URD

Post  MI-Lineman on Wed Feb 15, 2012 11:24 pm

rcdallas wrote:
MI-Lineman wrote:GROUNDS!! I've seen new 14.4 cabinets fail (polly insulators flash over) cuz they (the cabinet) were changed at one time but not the ground rods!! You know how the rods eventually corrode away to nothing more than a spear about a foot in the ground! You may never notice this on our 4.8 cabinets! I try to tell guys if ya got the cabinet off DRIVE NEW RODS!! It's only your life depending on those ground rods at a later time during an outage while you're leather gloving!!

Dirt and weeds, see a lot of dirty cabinets and weeds that have flashed over!!

Me, I would never touch the outside of a 14.4 cabinet after some of the sh!t I've seen!

As for the conductor itself I can't think of any abnormal or unusual conditions do to the higher voltages?

Wish Cowboy would sign up! He'd have a few I bet!

The soil conditions must be pretty acidic over there in the great north...where I came up driving a ground rod was pretty much useless; sand! Where I'm at now there is a ton of salt in the soil eating direct bury alive.

I'm glad you mentioned it; now I'm just going to have to be more aware of it now that you mentioned it.

This is more problematic on 14.4 and above as far as ground rods or you just saying?

In some areas the ground can be pretty acidic! As for being problematic on 14.4 it's just somethin you'll see more on 14.4 than 4.8? That 14's always searching for a way home! Arrow
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Re: Greater than 7.2kv URD

Post  lewy on Sun May 06, 2012 10:01 pm

lamartin.cvec wrote:So one of the big problems is just the bigger wire size not being as agile; I've seen that not to long ago where some 1000mcm was pulled in direct from the sub to feed an industrial customer 7200 but using 25kv cable. I had move some elbows and it's not to giving in flexibility.

So it's going to have more of a tendency to track and stuff; in other words no time to diddle daddle go home with it, period.

It's funny you mentioned switching in the rain and stuff it was just a few months ago where I had to switch in a padmount during the rain and when I opened the lid nobody plugged the insert; I was livid. All I could think is man the conditions are right.

What are your thoughts on putting the tickler wire around the insert and the bushing well? I was brought up to always put one there. Now I wonder how much it could hit the fan on some 25kv if it didn't have it.

Yeah I hear you on the bolt on, that's definitely not anything you do hot. We have that in around the mall and downtown stuff, t-bodies, etc.

When you get time; NEED INPUT. geek

Absolutely add the static/bleeder wire to the inserts, elbows , and arresters. At higher voltages they will break down as they build up induction and it snaps over to the can trying to bleed it's self off. Also be aware of the drip cup for the bayonet fuse--DO NOT let the tx oil drip on the inserts--oil and inserts do not play well together the oil will cause the inserts to rupture and break down.

T-bodies are not allowed here and with good reason:they are junk. If you need a tbody then you really need a junction/switching point or the route of the line needs to be redesigned.

As for the million? sounds like you need to cut over some line to 24.9/14.4 drop some amps and lower some wire size. Gotta love engineering.

Work safely,

L.A.Martin
Journeyman Div III
CVEC[/quote]
You say T-bodies are junk. We use them all the time on our main feeders (27.6/16 kv) with Vista switches, then distribute on a loop to the individual transformers some times within the same switch gear & sometimes between switchgears. We never have to pull the T-bodies live. The only other option to T-bodies that I am aware of is PMH switch gear that in my opinion are no where as good as a Vista switch though cheaper. I personally like the Vista switch. I am curious what you use on your main line U.G. feeders if you can't use T-bodies & why you think they are junk?

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Re: Greater than 7.2kv URD

Post  hotwiretamer on Sun May 06, 2012 11:47 pm

We use T-bodies in our PMH's, and also have used them in vaults, and pull cabinets. Only on out feeders. I believe Safety Line makes a hotstick "kit" for unbolting, and grounding t-bodies!

SDG&E uses them. I don't think I would try it!

However, what is wrong with T-bodies?
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Re: Greater than 7.2kv URD

Post  rcdallas on Mon May 07, 2012 5:23 pm

Two things:

1)I'm only familiar with the PMH switchgears; what's the difference between a Vista and a S&C PMH?

2)Did not know there was a kit specifically designed for grounding T-bodies...will have to look into that.

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Re: Greater than 7.2kv URD

Post  lewy on Mon May 07, 2012 5:41 pm

rcdallas™ wrote:Two things:

1)I'm only familiar with the PMH switchgears; what's the difference between a Vista and a S&C PMH?

2)Did not know there was a kit specifically designed for grounding T-bodies...will have to look into that.
PMH switch gear everything is exposed, with a Vista switch it uses T-bodies & the terminations are on one side of the gear & the operating side is on the opposite side. We have the tool that you would use to install or remove T-bodies live, not dropping load, but with the Vista switch you have a visual open as well as a ground position, but we install an elbow ground on the end of the T-bodie without removing it from the gear when using it for isolation. I am only aware of the 2 basic ways of using sectionalizers either with T-bodies or exposed terminations in PMH switchgear, that is why I am curious what Mr Martin uses if they don't use T-bodies because I defiantly prefer Vista switches over PMH switchgear.

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Re: Greater than 7.2kv URD

Post  CanadianLineman on Mon May 07, 2012 5:48 pm

I have never removed T-bodies live but thinking about it it should be a simple task. I don't understand the issues with 14.4 or even 19K to ground using proper LB elbows. I guess I don't live in an area where a lot of salt is used.
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Re: Greater than 7.2kv URD

Post  lewy on Mon May 07, 2012 6:44 pm

CanadianLineman wrote:I have never removed T-bodies live but thinking about it it should be a simple task. I don't understand the issues with 14.4 or even 19K to ground using proper LB elbows. I guess I don't live in an area where a lot of salt is used.
Removing or installing live becomes more difficult when you get into the larger wire sizes, you have to set the T-bodies properly before screwing them in place. The issue with pulling live elbows at the higher voltages has nothing to do with salt it has to due with temperature, around 0 they will flash over because of the partial vacuum, that is why they go to vented inserts.

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Re: Greater than 7.2kv URD

Post  lamartin.cvec on Sun May 20, 2012 11:03 am

Sorry for the confusion, I was referring to underground Direct burial "t body" splices--not "t body" elbows or back to backs or piggy backs or what ever else they may be called. As with most things in our trade there are probably 40 different names for the same thing.

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Re: Greater than 7.2kv URD

Post  MI-Lineman on Sun May 20, 2012 1:08 pm

lamartin.cvec wrote:Sorry for the confusion, I was referring to underground Direct burial "t body" splices--not "t body" elbows or back to backs or piggy backs or what ever else they may be called. As with most things in our trade there are probably 40 different names for the same thing.

work safely,

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We have a few T-bodies in some of our areas and I was on one once with a co-worker tryin to locate it? I think a lot of ours came from trailer parks who sold us there urd systems that they owned individually? I can't imagine a power co. would be stupid enough to purchase them and use them on their systems? In-fact who the hell would come up with that? They never thought of locating it some day? Rolling Eyes

Good to see ya Martin! Hows the weather over there?? sunny
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