How do they fix Power Lines?

[exranger06]

Originally Posted By: csx7006
Just out of cuiosity. I have a S&C cutout that I brought off feebay. Is there a way I can put one of these for my shed?What size fuses can I get?

You mean you want to mount a cutout somewhere and use it to energize your shed? From the main panel in your house? I think you should ask a home inspector what he thinks of that (He won't like it, and for good reason.)

But, to answer your question, there are many different sizes from 15A up to 100A. There are many different fuse curves too (determines if a fuse blows quickly or slowly).

But seriously, don't do it.

 

[JimPghPA]

Originally Posted By: electrolover
They first run a the line directly to ground so they can work on it a little safer and then splice in the new line. After its done they remove the ground rods and conductors and its all good.
Im not a lineman, but I am an electrician and I see it done once. It was a point of interest for me so I payed close attention. What I found out is you cant pay me enough to be a lineman


I never worked as a lineman, but have taken the high voltage classes. To the best of my memory:

Here in Pittsburgh Pennsylvania, the linemen first get a clearance permit from "Systems". Systems is a big room with a huge map on a huge wall, and computer terminals that allow the systems operator to open the big breakers at the substation, and then when the power is off they can open sectionalizers (a smaller switch that can not interrupt the current on a live line, or handle picking up load when re-energizing a line that has no power). Systems gives a clearance to the linemen in the field. They put that clearance paperwork in their pocket.

Sectionalizers enable a small section of the grid to be disconnected instead of a larger section. Normally this allows minimizing the number of customers that are without power. In a large power outage with many lines down the sectionalizers still allow picking up lines that are repaired without applying power to sections of line that are still being worked on.

The saying is that if the lineman gets killed on the job and does not have the clearance paper in his pocket the company insurance is not going to pay on the claim.

Then after systems has given a clearance, the line-men then test the line with an insulated pole probe to check for voltage, then they apply a crowbar (a thick wire cable attached to ground and thrown over the power line, or clamped to it). If the line were hot the fireworks could be enough to hurt or kill someone when the crowbar is applied.

Only after the clearance is given from systems, and the line is probed with a long insulated voltage probe stick, is a ground (crowbar) attached.

(BTW those long probes, the insulated boom on the bucket, the insulated rubber selves the linemen wear, the insulated rubber gloves, and the leather gloves that go over the rubber gloves to protect the rubber gloves from damage, ALL have to be inspected by other people in other sections of the company on a regular schedule).

And the removal of the crowbar and telling systems the line is clear and ending the clearance permit, is also something done in a very serious and deliberate order.

 

[VNTS]

If it is down, they will patrol the line to find the fault.

They can open the upstream recloser, and tag it out, also talk to dispatch if the equipment has Scada control. They splice the conductor and repair, then re-energize either close it in manually or remotely.

Note a lot of the work is done live out of bucket truck with specially insulated gloves, good for 7200 L-G.

stuff that is interesting is when 345KV Breakers and switches are opened, quite the show.

 

[exranger06]

There are several ways to sectionalize a line. A "sectionalizer" can mean any device used to isolate part of a circuit, but usually refers to a device that's actually called a sectionalizer. These devices only isolate parts of a circuit during an event by coordinating with reclosers or breakers. They cannot break a load. My utility doesn't use them at all.

Other ways to isolate sections are fuses/cutouts, switches, and reclosers.

 

[JimPghPA]

There are automatic reclosing systems connected to the big breakers in the substation, and the sectionalizers. When a fault is detected on a line (such as a tree touching a line) the automatic reclosing system first opens the big breaker in the sub-station because the big breaker can handle interrupting the large amount of current at the high voltage. Then sectionalizers are opened. Then after a time out (usually very short for the first one, something like one cycle of the line) the automatic reclosing system closes the big breaker in the sub-station. If the fault is still on the line the big breaker is opened again, and then more sectionalizers are opened, and then a longer time out is used (something like one to fifteen seconds) and the big breaker closes again. If the fault is still on the line the big breaker opens again. If a third try is programmed into the automatic reclosing system more sectionalizers are opened and a longer time out (something like fifteen seconds to 90 seconds) is used and then the big breaker closes again. If the fault is still on the line the big breaker opens again, and is locked open. Systems is informed by a signal that the big breaker is locked open. Now a lineman must find and clear the fault (with the proper permit to work on that section), and when done the lineman notifies systems that the fault is cleared and that line is ready to be brought back up, and systems then can override the lockout of the breaker and bring that line up by closing that breaker.

So one big thing to learn from this is that if a high voltage line is down and stops dancing around and you think that is has no voltage, while it may have no voltage NOW, any time in the future some automatic system may try to bring that line back up. So NEVER approach a downed high voltage line. Only a lineman who has received proper clearance permit from systems, can safely approach a downed high voltage line. If someone else get near a downed line and an automatic system re-energizes that line to try to bring it back up, they can be killed.

 

[exranger06]

Originally Posted By: JimPghPA
There are automatic reclosing systems connected to the big breakers in the substation, and the sectionalizers. When a fault is detected on a line (such as a tree touching a line) the automatic reclosing system first opens the big breaker in the sub-station because the big breaker can handle interrupting the large amount of current at the high voltage. Then sectionalizers are opened. Then after a time out (usually very short for the first one, something like one cycle of the line) the automatic reclosing system closes the big breaker in the sub-station. If the fault is still on the line the big breaker is opened again, and then more sectionalizers are opened, and then a longer time out is used (something like one to fifteen seconds) and the big breaker closes again. If the fault is still on the line the big breaker opens again. If a third try is programmed into the automatic reclosing system more sectionalizers are opened and a longer time out (something like fifteen seconds to 90 seconds) is used and then the big breaker closes again. If the fault is still on the line the big breaker opens again, and is locked open. Systems is informed by a signal that the big breaker is locked open. Now a lineman must find and clear the fault (with the proper permit to work on that section), and when done the lineman notifies systems that the fault is cleared and that line is ready to be brought back up, and systems then can override the lockout of the breaker and bring that line up by closing that breaker.

So one big thing to learn from this is that if a high voltage line is down and stops dancing around and you think that is has no voltage, while it may have no voltage NOW, any time in the future some automatic system may try to bring that line back up. So NEVER approach a downed high voltage line. Only a lineman who has received proper clearance permit from systems, can safely approach a downed high voltage line. If someone else get near a downed line and an automatic system re-energizes that line to try to bring it back up, they can be killed.

You just described the function of a recloser. They are located on utility poles. The breaker at the station does not open and close several times like that, the recloser does.

 

[JimPghPA]

Originally Posted By: exranger06
There are several ways to sectionalize a line. A "sectionalizer" can mean any device used to isolate part of a circuit, but usually refers to a device that's actually called a sectionalizer. These devices only isolate parts of a circuit during an event by coordinating with reclosers or breakers. They cannot break a load. My utility doesn't use them at all.

Other ways to isolate sections are fuses/cutouts, switches, and reclosers.


Yes, some systems do not use the remote controlled secionalizers. One of the big things is to be aware of with manual switches, cutoffs, fuses, is if the device can or can not break or pick up a load.

Also, there are different ways to configure the lines. In Pittsburgh and many other high populated areas rings are used. With rings you can remove very small sections with sectionalizers or manually operated switches, and only drop a very small section of the grid such as one street. Ring systems generally have rings of several voltage levels. And as the distance from the center of the populated area gets further away, the voltages used on the high voltage rings are usually higher.

In the rural areas like farm land or areas where there are huge spaces between customers, rings are not cost effective, and usually branch circuits. A branch is similar to a tree limb branch. If a fault occurs and there are means to break the fault from the main line, many other customers further down the branch are still without power when the fault is broken free. And they stay without power until the fault is removed. This is why customers who live in rural areas often have longer power outages than those living in a city.

 

[csx7006]

Originally Posted By: exranger06
Originally Posted By: csx7006
Just out of cuiosity. I have a S&C cutout that I brought off feebay. Is there a way I can put one of these for my shed?What size fuses can I get?

You mean you want to mount a cutout somewhere and use it to energize your shed? From the main panel in your house? I think you should ask a home inspector what he thinks of that (He won't like it, and for good reason.)

But, to answer your question, there are many different sizes from 15A up to 100A. There are many different fuse curves too (determines if a fuse blows quickly or slowly).

But seriously, don't do it.



I want to use it for a lectric fence.

 

[JimPghPA]

Originally Posted By: exranger06
Originally Posted By: JimPghPA
There are automatic reclosing systems connected to the big breakers in the substation, and the sectionalizers. When a fault is detected on a line (such as a tree touching a line) the automatic reclosing system first opens the big breaker in the sub-station because the big breaker can handle interrupting the large amount of current at the high voltage. Then sectionalizers are opened. Then after a time out (usually very short for the first one, something like one cycle of the line) the automatic reclosing system closes the big breaker in the sub-station. If the fault is still on the line the big breaker is opened again, and then more sectionalizers are opened, and then a longer time out is used (something like one to fifteen seconds) and the big breaker closes again. If the fault is still on the line the big breaker opens again. If a third try is programmed into the automatic reclosing system more sectionalizers are opened and a longer time out (something like fifteen seconds to 90 seconds) is used and then the big breaker closes again. If the fault is still on the line the big breaker opens again, and is locked open. Systems is informed by a signal that the big breaker is locked open. Now a lineman must find and clear the fault (with the proper permit to work on that section), and when done the lineman notifies systems that the fault is cleared and that line is ready to be brought back up, and systems then can override the lockout of the breaker and bring that line up by closing that breaker.

So one big thing to learn from this is that if a high voltage line is down and stops dancing around and you think that is has no voltage, while it may have no voltage NOW, any time in the future some automatic system may try to bring that line back up. So NEVER approach a downed high voltage line. Only a lineman who has received proper clearance permit from systems, can safely approach a downed high voltage line. If someone else get near a downed line and an automatic system re-energizes that line to try to bring it back up, they can be killed.

You just described the function of a recloser. They are located on utility poles. The breaker at the station does not open and close several times like that, the recloser does.


I do not agree with this last statement.

The recloser is the device that controls the sectionalizere.

The reclosers are located in substations. Sectionalizers are located on poles.

Sectionalizers can not handle dropping a fault, or picking up a line that still has a fault on it.

The breaker in the substation handles breaking a fault, or picking up a line with a fault on it after sectionalizers have broken the circuit down to smaller sections.

 

[xxch4osxx]

Originally Posted By: VNTS
If it is down, they will patrol the line to find the fault.

They can open the upstream recloser, and tag it out, also talk to dispatch if the equipment has Scada control. They splice the conductor and repair, then re-energize either close it in manually or remotely.

Note a lot of the work is done live out of bucket truck with specially insulated gloves, good for 7200 L-G.

stuff that is interesting is when 345KV Breakers and switches are opened, quite the show.
There quite a few videos on youtube showing 345 up to 500KV switches opening. Got to love jacob's ladders!

 

[JimPghPA]

BTW, reclosers run on 130 DC from the bank of batteries in the substation.

 

[exranger06]

Originally Posted By: JimPghPA


I do not agree with this last statement.

The recloser is the device that controls the sectionalizere.

The reclosers are located in substations. Sectionalizers are located on poles.

Sectionalizers can not handle dropping a fault, or picking up a line that still has a fault on it.

The breaker in the substation handles breaking a fault, or picking up a line with a fault on it after sectionalizers have broken the circuit down to smaller sections.

You don't agree with it? It's not an opinion, it's a fact. Reclosers are located on poles. Sectionalizers are entirely OPTIONAL. Like I said, my utility (as in, the utility I work for and do engineering for every day, but what do I know, right?) doesn't even use sectionalizers, but we do have reclosers on the poles. The recloser breaks the load, closes back in to check if the fault is still there, and if the fault is still there after a few cycles, it locks out and keeps the power off until someone manually resets it at the pole.

This is a recloser:

 

[exranger06]

We use ABB reclosers like these:

And Whipp and Bourne reclosers like these:

 

[Shannow]

Originally Posted By: crw
I wonder why more lines aren't buried? When I was growing up in the Seattle suburbs (1970's) all of my neighborhood had no overhead lines where the weather could impact them. But where I live today, in Idaho, overhead lines are still all over.


As others have posted, expense is one issue.

Heat rejection is another. Underground cables have to be insulated, which on the high power stuff is typically XLPE (Cross Linked Poly Ethylene) these days, but often used to be paper/pitch/transformer oil etc. The heat from the current flowing through the conductor has to pass through the plastic insulation, PVC sheath, air gap to the conduit, and into the soil. Some have passages in the middle to allow dry nitrogen cooling etc. (A real pain when the oil runs down into a low spot and the nitrogen can't pass)

Heat from an overhead is dissipated by convection, and is material, as on a hot day, at peak the overheads can get really hot (heat is measured by how far the catenery sags as the cable lengthens).

Underground cables are easily discovered by back-hoes.

Easier to find a downed overhead than the point at which a cable failed...and it has to be repaired where the break is, regardless of how inconvenient the excavation is.

Cables running parallel can "jump" under the electromagnetic forces when they experience a short. In the power stations, the really big High Voltage/current cables are clamped down to their trays.

The magnetic field surrounding in service cables can influence the other phases, even on the same circuit, shifting power factors and phase voltages, requiring their positions to be swapped regularly (you can see the phase swapping on overheads, when they rotate the positions of the conductors), arrange the phases in a trefoil arrangement, or buy expensive 3 phase cables. (Joining kits for a 3 phase cable are massive.

The magnetic field around a cable can induce a current in a cable being worked on (but safety rules help this, but can be a trap).

 

[Shannow]

Originally Posted By: exranger06
Originally Posted By: JimPghPA


I do not agree with this last statement.

The recloser is the device that controls the sectionalizere.

The reclosers are located in substations. Sectionalizers are located on poles.

Sectionalizers can not handle dropping a fault, or picking up a line that still has a fault on it.

The breaker in the substation handles breaking a fault, or picking up a line with a fault on it after sectionalizers have broken the circuit down to smaller sections.

You don't agree with it? It's not an opinion, it's a fact. Reclosers are located on poles. Sectionalizers are entirely OPTIONAL. Like I said, my utility (as in, the utility I work for and do engineering for every day, but what do I know, right?) doesn't even use sectionalizers, but we do have reclosers on the poles. The recloser breaks the load, closes back in to check if the fault is still there, and if the fault is still there after a few cycles, it locks out and keeps the power off until someone manually resets it at the pole.

This is a recloser:

I see both arguments...

In the big stuff, there are circuit breakers, which are controlled by the protection systems to provide a reclose function.

They can be arranged to sectionalise a yard under the control of the control system.

Further sectionalisation/permanent isolation is provide by Air Breaks (oft have earth switches with them)

e.g. from right to left
Current Transformer
Circuit Breaker
Air Break Switch.

 

[The_Jeff]

Originally Posted By: JimPghPA
There are automatic reclosing systems connected to the big breakers in the substation, and the sectionalizers. When a fault is detected on a line (such as a tree touching a line) the automatic reclosing system first opens the big breaker in the sub-station because the big breaker can handle interrupting the large amount of current at the high voltage. Then sectionalizers are opened. Then after a time out (usually very short for the first one, something like one cycle of the line) the automatic reclosing system closes the big breaker in the sub-station. If the fault is still on the line the big breaker is opened again, and then more sectionalizers are opened, and then a longer time out is used (something like one to fifteen seconds) and the big breaker closes again.


I expect every system is different. At my work (TV station) our stuff is sensitive to "bumps" that my boss describes as "missing six cycles". It's enough to make the roof air conditioners "thump" but is too short to switch stuff over to UPSes. We'll find things days later not working right that reset with a proper 30 second power off/on cycle.

So is this, more or less, what you're describing? I appreciate not walking around in the dark, but dang, this flickering really stresses power supply capacitors.

 

[andyd]

You can buy a gel cell powered fence charger that is solar powered .

 

[VNTS]

A recloser is genreally on a Distribution Ciruit, can be 3 phase single phase.

The idea is, when a limb brushes or falls, the fault occurs and the device opens, it will then close back in, if the fault is still there it will open again, then close back in one final time and if the fault is still there it will trip open and stay open. Some are SCADA controlled and the info will be scene in the comm center. Others are not and customer will call in.

These devices can be oil filled equipment, vaccum bottle etc.

what you see is the off on off on lockout. Utilities also so use fused cutout,fuse blows and opens the cutout, again someone without power calls it in.