View Full Version : while working between grounds?
reppy007
02-13-2012, 01:27 PM
Any good ideas for crews that are working between grounds..............here in this area they sometimes tape those traffic flags on the primary where grounds are installed.......cant help but notice them.........and has anyone ever worked between grounds......and have somebody else make the circuit or wire hot?
bren guzzi
02-13-2012, 01:38 PM
99 % of the time we work between grounds. Only once in 30 years did someone "try"an switch the line back in. . We were fifished working and left a set on. Just tripped the fuses. ..the enginer and foreman ( sent for re training).
Pootnaigle
02-13-2012, 01:57 PM
Ummmmm This un will boggle yer mind. During a major storm a crew held a clearance on a downed section of the trunk feeder. They released the clearance n Dispatch sent me to a set of underhung disconnects to close them. I knew nothing about where they had been working only that it was my job to close the switch that had been opened to isolate for them. I took the switching order from the dispatcher and closed 2 of the 3 blades in and while moving the stick to the last blade the world blew up right in front of my eyes. And took out the entire feeder . I opened the other 2 back up and dispatch contacted the crew that had held the clearaance , re energized the feeder and the crew found an additional set of grounds that they had either forgotten or someone decided to put on in excess of their clearance and never told anyone about. The second time around all went well. But the puzzling thing was 2 of those blades were completely closed while grounds were still installed and it took a while after closing the 2nd to even see the fault. I wudda thunk it shudda been immediate n to this day dunno why it wuznt.
reppy007
02-13-2012, 02:43 PM
Ummmmm This un will boggle yer mind. During a major storm a crew held a clearance on a downed section of the trunk feeder. They released the clearance n Dispatch sent me to a set of underhung disconnects to close them. I knew nothing about where they had been working only that it was my job to close the switch that had been opened to isolate for them. I took the switching order from the dispatcher and closed 2 of the 3 blades in and while moving the stick to the last blade the world blew up right in front of my eyes. And took out the entire feeder . I opened the other 2 back up and dispatch contacted the crew that had held the clearaance , re energized the feeder and the crew found an additional set of grounds that they had either forgotten or someone decided to put on in excess of their clearance and never told anyone about. The second time around all went well. But the puzzling thing was 2 of those blades were completely closed while grounds were still installed and it took a while after closing the 2nd to even see the fault. I wudda thunk it shudda been immediate n to this day dunno why it wuznt.
Dang Poot,,,,,thats what I was thinking while reading your post.......I would bet money on the circuit locking out immediately...........Ive never heard of that happening quite like that.
bren guzzi
02-13-2012, 03:23 PM
This is a brief idea of how we work. Firstly 90% of our lines are back feedable. So we put air then there break switches at certain points of our lines. If there is 40 or 50 span with no spurs ( T offs) ,then no switches. If we are working on a section of line we isolate a section.well an engineer isolates it ,through control. He then issues us a permit for that section of line under his supervision we put a set of earths (grounds) on called CME,s. Then we will place additional earths on. WE MUST BE in sight of an earth..... We put our additionals on the back of the permit as a reminder "the section might be out for weeks. SO we then take our earths off. And sign our permits off to the engineer. He then supervises the CME removals. Rings control and then switches the line back in.
SIMPLE.... :).
reppy007
02-13-2012, 03:31 PM
There was a day long ago when I was I believe a 2nd or 3rde sixth month apprentice........we were working on a lateral only one or two spands away from the take off pole..............line fuses must have been down aways from us..................forgot actually what we were doing but the lineman had 2 or 3 pairs of web-jacks/nylon hoist on the #2 primary.......isolating it from the energized portion............had grounds on the de-energized side.............well it was a pretty day when all of a sudden a small rain shower came in,,,,,,,,,,,,,,yes it burned down the pea-vine guess the jacks were a little dirty.........but they looked clean.
reppy007
02-14-2012, 02:55 AM
Poot.....lets back up a little..............I doubt that you were the one that finally removed those grounds that you were talking about....................but just in case...........wonder what kind of shape they were in after heating them up...............I bet there were no marks on them.
Pootnaigle
02-14-2012, 07:49 AM
dunno I never did see em. I wuz patrollin that section after it all blowed up lookin but dispatch sent me back to the switch n sed the crew had found another set of grounds. I bleve it was a contract crew with a birddog. Lotta alley stuff.
dooghi
02-14-2012, 10:29 AM
Hey Poot do you think that maybe the OCR that was protecting that piece of line had a ground fault on it? So when you closed the first two switches it just thought it seen load, till the imbalance got to the right threshold to open it?
Pootnaigle
02-14-2012, 10:42 AM
Ummmmmm I just dont know. But to me if it was grounded that shudda been a solid fault on the first phase I closed and when I closed the second phaze that shudda been a direct crossphase It gave me time to lower the stick a tad and move under the third phase before going south and i have never understood why.
reppy007
02-14-2012, 11:19 AM
Ummmmmm I just dont know. But to me if it was grounded that shudda been a solid fault on the first phase I closed and when I closed the second phaze that shudda been a direct crossphase It gave me time to lower the stick a tad and move under the third phase before going south and i have never understood why.
Makes me wonder too..............maybe something wrong with the ocb's at the sub.......relays.....settings.................I GIVE UP..............
rob8210
02-16-2012, 09:31 PM
How far from the station was it Poot?
Pootnaigle
02-16-2012, 09:46 PM
Ummmmmmmm the switches wernt far at all maybe a mile dunno for sure where the fault wuz.
rob8210
02-16-2012, 09:56 PM
I have seen where primary was down on cement sidewalks, burning away , only a few spans outside a station. The relays in the station were set high enough that they did not recognize the fault. Do you suppose that could be the case ?
Pootnaigle
02-16-2012, 10:02 PM
Ummmmmmm I really dont think so. The breaker operated jus fine on the original fault, and it seems to me a crossphase condition would always trip one no mater what the setting
rob8210
02-16-2012, 10:07 PM
Good point, my only other idea was maybe the grounds were in very poor condition and didn't present a good fault for the breaker to see
Pootnaigle
02-16-2012, 10:14 PM
I honestly dunno n likely never will....... The point I wanted to make was that its dern sure possible Kause I have witnesed it,,,,,
rob8210
02-16-2012, 10:17 PM
One thing I have found in this kind of work, if you can dream up something, you'll probably see something even stranger.
rob8210
02-16-2012, 10:19 PM
Nice chatting with ya Poot, keep up the good work!!!
tramp67
02-16-2012, 10:27 PM
I was working in Beaumont Texas on cleanup after Hurricane Rita, got sent out to a call of primary on the ground. The utility crews were busy checking out another feeder, trying to find out why the station breaker had locked it out. I was patrolling the feeder they sent me on, and found the fire department on scene working on a grass fire from one of the phases laying on the ground (7200/12,470). I decided to patrol the rest of the feeder, found the same phase burned to the ground in three more places until I found a single phase tap wrapped around the neutral. The cutout for the tap was on the other side of the highway from the feeder, and apparently a truck hauling hurricane debris snagged the single phase and tore it down, one end wrapping itself around the mainline neutral. The primary kept burning down towards the sub, there was a set of 200T's protecting the line that finally blew about 6 spans from the sub. Turns out that when the sub was built, the control wiring for the circuit I was on had gotten crossed with the circuit the utility trouble crew was working on. When the breaker saw the fault current, the messed up control wiring tripped the wrong breaker! Kinda opened up a can of worms for the substation electricians.
Working on another utility's property in Kansas, we were getting one shot on a feeder every day for about three weeks, the engineer gave us the recloser number and wrote up the switching orders. One day, another crew knocked two phases together, and burned the line to the ground, it wouldn't trip the recloser. Kept burning for about a half hour until the dispatcher realized they kept putting the non-reclose on the wrong circuit.
Poot, maybe your line got knocked out with the first ground, and a dispatcher screwed up and re-energized your circuit. That's the only thing that seems to make sense from what you described. I'm sure it's happened more than once!
Pootnaigle
02-16-2012, 10:47 PM
Ummmmm I dont think so Course ya jus never know what a dispatcher mite do. The voltage was 13.2/7620 AND had a hospital ahead of the switch that was opened to isolate. It was late late at night or early early inna mornin and I wished I had been able to ride the thing completely out and see where those grounds were but we were soooooo busy i didnt have time. This too happened in Beaumont Texas.
But speaking of trash haulers we had a major problem with them guys stackin crap up so high they tore down everything they passed under. They tore down a lot of wire and caused a lot of extra work and outages once we had some power to deliver
reppy007
02-17-2012, 05:20 AM
Back in the 80s.........around 1985 when I was an apprentice........we had a job to do behind a line-fuse.....forgot exactly what we were doing.............but the lineman were about to work on the primary............the foreman was talking about putting a work tag or 1 shot on the circuit.........the lineman thought he was nuts............but if my memory is correct,we eventually did get a work tag behind that line fuse..............that was the only time Ive seen that done.
Pootnaigle
02-17-2012, 07:03 AM
Ummmmmmm I bleve that has become SOP nowadays. The theory is that the breaker will trip before the fuse clears?
rob8210
02-17-2012, 07:16 AM
Most utilities here require you to have a holdoff even behind a line fuse. The way it was explained to me is , when the breaker operates the first time it is to give a fuse a chance to blow clearing a problem, the second time is last chance , and the third time is out and stay out. Of course we have to trust the fellas setting up the protection circuits to do it right and sometimes done right means the relays are set too high to see a small fault. I realize you didn't get a look at them grounds , Poot, but that is why I suggested they may have made a very poor ground and took so long to let go. I had it happen on a storm once , after clearing a tree, putting the line back on, the bird dog and our sub foreman went on down the line , we had the truck all packed up when ssssst, the line fuse blew ( it took a good 5 minutes) , just after that the bird dog came racing yelling for us to open it up. Too late was all I could say. There was another spot about a half a mile down the line where it was all on the ground and the primary and neutral was all wrapped together.
Lineman North Florida
02-17-2012, 07:50 AM
We don't traditionally get the reclosures off when working behind fuses unless there are special circumstances, we went to K fuses quite a few years ago because we were getting breaker operations on virtually every feeder because of the KS fuses we used were slow to blow and with all the digital stuff having to be reset weekly everybody complained, nowadays we have very few breaker operations from the squirrels that used to make everyone complain. I'm not saying it's a bad idea to get the reclosures off the breaker at the sub as it is another form of protection to keep it from coming back on you in case of a mishap. How many of you have been told that the automatic reclosures are not for your protection, they are for the equipment and system protection.:rolleyes:
HIVOLTS
02-17-2012, 08:13 AM
One explanation: the clearance was behind a set of hook switches and while the work was progressing the breaker at the sub had it's R switch closed as normal. When you closed the first switch the breaker did trip imediatley and you never knew it. If the breaker has an old electromechanical recloser they can be slow to respond giving you enough time to get the second blade closed and move on before the breaker reclosed. The second shot on the breaker is always a time overcurrent as the instantaneous protection is blocked so tripping would be a little bit slower.
Pootnaigle
02-17-2012, 08:26 AM
Ummmmm I understand what you are saying but ummmm member this happened very late at night and I would have noticed the trip when the lights around me went out. Honestly that is a plausable explanation but I dont think thats what happened.
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