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What to Do After Finding Hot Connectors on Overhead Power Lines (2017) [video]
- camtarn 8y agoThis video shows an aerial line crew (lineworker and pilot in a helicopter) bypassing a high-resistance splice in a 220kV overhead power line, attaching a large bolt-on shunt while the line is still live. The lineworker sits on a platform on the outside of the helicopter while doing the work, in an incredible demonstration of precision helicopter hovering.
- laumars 8y agoI've been having a stressful week (thus far) at work and this video really puts things into perspective.
- mchahn 8y agoThat lineman deserves a raise, no matter what he makes. He falls in the category of workers who are lowered into nuclear reactors to cleans things up.
- sevensor 8y agoI saw a crew like this at work once. No idea what they were working on, but they were doing it to lines that crossed over the highway I was driving on. I was moving at highway speed, so my mind didn't really have a chance to boggle until I was already past. Those helicopter pilots must have a very steady hand.
- ableal 8y ago> very steady hand I don't know the first thing about helicopters, but the negative feedback circuits that keep things steady in many applications, from power supply voltages to Segways, could help with that. It's a very simple basic concept that has been around for many decades, even before analog electronics, never mind digital devices: https://en.wikipedia.org/wiki/Negative_feedback https://en.wikipedia.org/wiki/Negative_feedback (I repeat I do not know if they are available in helicopters. It may well be the pilot doing it by hand the hard way.)
- rzzzt 8y agoSearch-and-rescue helicopters are the most likely to have that capability: https://en.wikipedia.org/wiki/AgustaWestland_AW139#Design https://en.wikipedia.org/wiki/AgustaWestland_AW139#Design https://en.wikipedia.org/wiki/Eurocopter_HH-65_Dolphin#Design https://en.wikipedia.org/wiki/Eurocopter_HH-65_Dolphin#Desig...
- halbritt 8y agoComputerized stability control systems exist, are quite prevalent, and have a thriving open source community. Check out: https://github.com/betaflight/betaflight/wiki https://github.com/betaflight/betaflight/wiki Granted, it's for hobby scale drones, but the same principles apply.
- dfox 8y agoThe physics involved in multi-rotor drones (or even counter rotating dual rotor toy-level RC helicopters) is significantly different from single rotor+stabilizer helicopters in that there is at least in theory point where the thing is dynamically stable.
- bri3d 8y agoFor what it's worth many toy RC helis exist with collective pitch tail rotor setups and full feedback stabilization - it started with tailrotor yaw hold automation and now they can stabilize in all axes. Check out something like Blade mCPx
- gjhan 8y agoThe dynamics, which are not just the rigid body dynamics plus the aerodynamics of the vehicle but also include many structural modes of the rotorhead and blades, are not scale invariant. An RC helicopter is proportionally stiffer in certain degrees of freedom by an order of magnitude (in rotor angular velocity and thrust:weight ratio e.g.), and so can ignore dynamical factors that dominate the control and structural sizing for manned helicopters.
- pdkl95 8y ago> Those helicopter pilots must have a very steady hand. Piloting a helicopter in general requires an incredibly steady hand on unintuitive controls that interact with each other in ways that are difficult to predict[1]. Being able to do that with high precision, a disturbingly small margin of error, and fatal consequences for almost any error is basically a superpower. [1] SmarterEveryDay has an interesting video[2] about learning to hover a helicopter, which apparently requires trying to hover (badly) until the brain learns how to abstract away all of the complexity. [2] https://www.youtube.com/watch?v=eXR1olg_I0w https://www.youtube.com/watch?v=eXR1olg_I0w
- lisper 8y agoIt is hard to overstate how difficult it is to hover a helicopter this precisely for this long. Helicopters are dynamically unstable. If you take your hands off the controls, they start to flip over almost immediately and become unrecoverable within 2-3 seconds. The best analogy I've heard: imagine trying to stand on a basketball. Now imagine trying to stand on a basketball without flailing your arms around. Now imagine trying to do that for half an hour while someone's life depends on you not screwing up even for a single second.
- chrischen 8y agoThey can’t do computer based stabilization?
- lisper 8y agoAuto-hover technology does exist, but it's not common. Also the pilot has to be able to do it manually in case the autopilot fails, and so most pilots will elect to do it manually at least some of the time just to stay in practice.
- dogma1138 8y agoIsn’t AFCS with hold position capability pretty much standard these days?
- lisper 8y agoNo. https://www.reddit.com/r/flying/comments/998c8b/helicopter_pilots_how_common_is_afcs_nowadays/e4lrcay/ https://www.reddit.com/r/flying/comments/998c8b/helicopter_p...
- tinus_hn 8y agoPerhaps the smart thing would be to practice in situations where an error does not cause someone else to get electrocuted.
- tkahnoski 8y agoA year or two back they recently did maintenance on a majority of the high voltage towers in the greenway behind my house. They sent out flyers to all the residents a few days ahead. This video shows once splice. I can't imagine the crew (or crews) that were working the miles of lines behind our house doing this for multiple days in a row.
- londons_explore 8y agoThis kind of splice repair should be rare. It only needs doing when the original splice was badly done.
- liareye 8y ago230kv
- trumped 8y agoI just watched it... this feels like deja-vu...
- docker_up 8y agoI have to admit, it was a fascinating video. The precision of the helicopter pilot is amazing. Just one wrong move though and both are dead. Surely there's a less risky way of doing this? How did the lineworker and helicopter not get electrocuted? Is it because they attached themselves to the transmission line, similar to how a squirrel doesn't get electrocuted? Or were the lines taken down or something (I find that hard to believe but maybe). At those levels, if they were at the same voltage as the lines, isn't there still a risk of arcing to another line?
- dreamcompiler 8y agoYes, most definitely. They still have to be careful about that. I expect it's an easy thing to avoid unless you're working on an inside conductor.
- sevensor 8y agoThe whole thing is a conductor. Those lines are insulated only by air. Edit: Misreading on my part. Parent meant "a line closer to the tower" not "a conductor within the line."
- titanomachy 8y agoPretty sure by "inside conductor" he means one of the lines closer to the tower. In the video I think he's working on the outermost conductor, i.e. the one furthest from the tower.
- sevensor 8y agoAh, good point. Grandparent is correct. Carry on!
- tzs 8y agoFor conductors that the helicopter cannot safely hover close enough to for the line worker to work on from the helicopter, they sling load the worker below the helicopter, lower him down to the conductor he needs to work on, and he attaches himself to the conductor and detaches from the helicopter, and the helicopter moves away from the lines. When the work is done, the above is reversed to extract the worker. There's a segment showing this in "Modern Marvels" episode S11E45, "Wiring America" starting at 23:44 [1]. I've also seen a documentary somewhere [2] that was similar but more focused specifically on line work. That had a clip showing a worker being lowered to a particularly difficult to reach conductor. There were at least 3 horizontal layers of conductors, with at least 3 parallel conductors in each layers, and the one needing work was in the middle horizontally and had at last 2 layers above it. For that one, they had several dry wooden poles connected end to end to form a kind of chain. They put this together in a dry area, then had a crew carry the pole chain outside careful to not let it touch the ground, so it would not get wet from the morning dew on the ground. One end was attached to the helicopter, which slowly started lifting it, with the crew that was holding it making sure to not release segments until they were sure they would not swing into the ground on the way up. Finally, the line worker was attached to the last segment. From then on, it was similar to the segment from Modern Marvels. They used the dry wooden pole chain because there was no way to reach the work conductor without whatever was suspending the worker simultaneously touch two of the above conductors, so it was imperative that this not short out things. I believe they used a pole chain rather than some non-conducting rope because a rope can get tangled in things or wrap around things. The pole chain consists of rigid segments, which are not going to get wrapped around anything. [1] https://youtu.be/vuRNs50VMJ0?t=23m44s https://youtu.be/vuRNs50VMJ0?t=23m44s [2] Probably on the History Channel or Discovery Channel.
- trestletech 8y agoCame for the video, stayed for the comments.
- dmritard96 8y agoSometimes I wonder why I have convinced myself that a desk job is the way to go. Then I remember that thats 220kV haha
- code_duck 8y agoI’ve learned that massive injury is actually less scary than mild or moderate injury because your body is overwhelmed, and you don’t really feel anything.
- freeone3000 8y agoYes, being dead does hurt less than a papercut.
- CNJ7654 8y ago"It is better to live one day as a lion than 100 years as a sheep."
- code_duck 8y agoI do not appreciate the useless dismissive statement. I’m talking about something intense I’ve experienced personally, and you are being rude.
- gambiting 8y agoJust because you are talking about it doesn't mean it automatically commands compassion or respect, and I am not saying this to be rude.
- jms703 8y agoWhat caused the line to overheat in the first place, requiring a splice?
- LeonM 8y agoUsually (internal) damage, caused by wind, rain, ice, etc. Could also be a manufacturing flaw. The damaged section will have a higher electrical resistance than what it was designed for, and as a result that section will dissipate more energy (heat). The splice/patch effectively increases the cross sectional area, which will lower the resistance, which will lower the dissipated energy, which will lower the heat.
- rtkwe 8y agoThe new splice also simply offers a lower resistance path full stop so most of the electricity will flow through the new splice instead of the damaged splice.
- kragen 8y agoI couldn't help but burst out laughing when the voiceover dude explained, "The pilot and the lineman are both doing an outstanding job despite very high wind conditions." Who on earth decides that very high wind conditions are a good time to hover your helicopter connected to a 230,000-volt power line? Couldn't they postpone the job for a day or two until the winds die down? The arc when the helicopter finally disconnects from the power line is pretty astounding. To the lineman, it's all in a day's work, I guess.
- markbnj 8y agoPossibly not? The high resistance splices are producing heat and at some point I believe they fail, which could affect the whole grid.
- londons_explore 8y agoWhen they get to 220C they are going to fail pretty quick. At those kinds of temperatures, oxidation is much faster, and you'll get heating and cooling stresses causing micro fractures as the load on the line goes up and down. As the resistance increases even a little, the temperature will increase more, making the above effects even worse.
- Declanomous 8y agoIt kind of looks like they are in a plains state somewhere. Having lived in the midwest nearly all my life, I can say with confidence that you are going to spend a lot of time waiting if you are waiting for a calm day. They probably just make sure the wind isn't gusting too much.
- neuralRiot 8y agoAlso probably the calm winds come when it's 5°F outside.
- qdcarnicelli 8y agoIt's actually eastern Pennsylvania, the helicopter has a Pennsylvania Power and Light (PPL) logo on it. If you look carefully in the background you can see the Delaware Water Gap in the mountains. Nevertheless, it's the same for the weather, Fall/Winter is gonna be windy enough you can't wait around for it.
- fcbrooklyn 8y agoThere was a video a few years ago that explained how this works: https://www.youtube.com/watch?v=r_1T2_l43Xo https://www.youtube.com/watch?v=r_1T2_l43Xo
- AWildC182 8y agoFor those who are interested, the helicopter is an MD-500. They're well known for being very stable and have pretty good control feel through mechanical-only linkages. As such, they're fairly popular for this kind of precision work. Another big application is aerial tree trimming: https://www.youtube.com/watch?v=OXcIqR01_d0 https://www.youtube.com/watch?v=OXcIqR01_d0
- peterwwillis 8y agoHere's an article on the pilots/flying: https://www.verticalmag.com/features/highvaluecargo/ https://www.verticalmag.com/features/highvaluecargo/
- mkagenius 8y agoAs an inventor how does one convince oneself to allow overhead wires carrying life threatening currents or any other such inventions. There exists so many inventions I would never pursue even if it occurred to me first, yet they exist and make our lives better.
- mikestew 8y agoI suppose someone figured that, after a point, the only question is how far your red mist will be spread should you have contact with a line. I mean, I'll put money on the fact that you're sitting in a room right now with nearly-exposed electrical contacts that can kill you. I guess it's not a great leap from there to "go ahead and hang them overhead, and try to make sure they won't fall down". OTOH, the only thing I've ever seen take down high tension towers was an ice storm so bad, they collapsed under the weight.
- rtkwe 8y agoYeah overhead on a strong tower is probably the best place for them. Underground they're way more likely to get hit accidentally and if the shielding failed it'd be impossible to tell where the danger was from the surface without specialized equipment.
- nomadiccoder 8y agounderground is more resilient to damage but harder to do maintenance and actually much more expensive at the distribution level
- rtkwe 8y agoIt would also increase the cost a lot due to the digging and actually requiring insulation that will hold up where the overhead lines are bare aluminum insulated by air.
- msisk6 8y agoExactly. It's mostly cost that keeps underground transmission lines limited to very specific situations. I forget the exact figure, but underground transmission is something like 20x the cost of above ground.
- floatrock 8y agoIn the overhead camera views, you can see about half a roll of duct tape on the lineman's helmet to hold the go-pro on, eg https://youtu.be/piQpLL5nD18?t=1m47s https://youtu.be/piQpLL5nD18?t=1m47s Although looking closer, it looks like it's the flexistrap type mount put over a smooth helmet, so makes sense. Point is, kludges are everywhere!
- jaggederest 8y agoA) That's electrical tape, I believe, and all the more appropriately so. B) you can also see someone holding the other camera on the ground, as well, which is interesting to see.
- hindsightbias 8y agoMultiple passes on 20 bolts on each side? Does it really have to be that complicated?
- NullPrefix 8y agoYou need multiple passes, because while doing the first pass, contact is still being made on an angle. Tie all the nuts at least once, then you won't have an angle and will be able to tighten better. Same like you should do on your car wheel. First put them all ass much as you can without force, then apply force. In a star bolt pattern.
- insomniacity 8y agoI suspect the other element is that if the line fails completely in the middle, the new splice is now structurally critical to holding the line up - so you need it to be as good, or better, than the original manufactured line.
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- scrumper 8y agoThis is excellent. I don't understand why there's an arc at the end when the lineman disconnects and pulls away the safety rod. That's there to keep the helicopter at the same potential as the transmission line, right? So why's there a potential difference when the safety rod is withdrawn?
- tlb 8y agoIt's a low-current arc. The circuit is completed by the capacitance between the helicopter and the ground. Assuming a spherical helicopter 1M in radius, the capacitance to ground is >>> 4 * pi * 8.8e-12 1.1058406140636071e-10 The current, at 220 kV and 60 Hz can be calculated >>> 60 * 2 * pi * 220e3 * 1.1058406140636071e-10 0.009171625977844317 or 9 milliamps. Enough to feel a good tingle. The power in the arc is >>> 220e3 * 0.009171625977844317 2017.7577151257497 or 2 kilowatts, so you can see the arc in daylight.
- scrumper 8y agoThank you for this.
- kragen 8y agoThank you! I wanted to calculate this, so I'm glad you did.
- tedsanders 8y agoFYI, and not that it matters, I think your current is off by a factor of 2/pi. There's no 2*pi in the current formula because the 60 Hz is the full frequency not the angular frequency. And there's an extra factor of 4 because in each full cycle sine wave there are four 220 kV steps: 0-220, 220-0, 0-(-220), (-200)-0. (and all of this of course assumes that the metal helicopter has low enough resistance to charge up to the full voltage)
- tlb 8y agoThe current through a capacitor is I = ωC, where ω is in radians per second (ie, 2𝜋 60 Hz). I think 220 kV is the RMS voltage, so you get RMS current from the formula above. Peak voltage would be √2 * 220 kV. Indeed, both the capacitor and the arc are in series, so actual current and power is somewhat less. As the arc grows longer, there should be an optimum length where you get 1/√2 of the maximum power.
- paavoova 8y agoThis got me interested into what it takes to become lineman. For Canada, it's: - extended driver's license requirements - some high school requirements (graduate, math and sciences) - physically fit year-round - pre-apprenticeship program - 3 year apprenticeship program, $30 pay - standard trade rate is $40 You probably get good benefits and disability securities, and overtime pay. But it means working in dangerous, frequently laborious, conditions, working away from home all over the province/country, and working frequent overtime. Makes me scratch my head when the people holding the infrastructure together get compensated so little.
- jacquesm 8y ago> Makes me scratch my head when the people holding the infrastructure together get compensated so little. Because they are very far away from where value is captured. That's a seriously annoying part of the way capitalism as we know it works: you only get paid a substantial fraction of the value created if you are near the point of value capture. That's why sales people tend to earn well.
- anonu 8y agoDon't you measure electrical resistance between two points? How is the guy measuring resistance on the line at a particular point?
- xvf22 8y agoVoltage drop?
- shaftway 8y agoIf you look closely at the rod there's a separate wire sticking out the side about 10 cms. It probably measures impedance over that 10 cm space. You can definitely see him use it to measure impedance between the line and the clamp, but the first one is hard to see because it's behind the clamp. The second is far easier.
- modells 8y agoThere's some great videos of installing spacers on multi-100kV live lines and of the Bond villian tree-trimmers.
- jcims 8y agoReminds me of one of my favorite youtube videos of all time https://www.youtube.com/watch?v=oBJyyEAw-6g https://www.youtube.com/watch?v=oBJyyEAw-6g I sincerely hope it's the actual lineman talking and that he takes a job in voice work when he retires.
- mkoryak 8y agohow much do those guys make?
- elorant 8y agoCouldn't we use something like that on wildfires for chopping down trees quickly?
- tgtweak 8y agoLike a big chain? If you're referring to the helicopter,I believe they already have helicopter mounted saw blades for trimming trees, in particular, for transmission line corridors. See here: https://youtu.be/Pla06PO6Odk https://youtu.be/Pla06PO6Odk
- BooneJS 8y agoI had the pleasure of watching something like this a couple of weeks ago on I90 in southern Minnesota. I came upon what looked like a helicopter entangled in the transmission lines, but after slowing down and opening the window, it was obvious the pilot was skillfully hovering there on purpose. It was impressive to see!
- ur-whale 8y agoWhat what happens at 2:57 in the vid. Did you spot the large spark?
- kiallmacinnes 8y agoI missed that, but it's also not all that surprising. The first thing they do is attach the platform to the cable. They use the "wand thing" first, so that their hands are away from the inevitable sparks, and allow the platform he's sitting on to equalise (voltage wise) with the wire. In other words, he's sitting on a platform thats 10k or more volts! Once equalised, a hook is attached - this is also conductive. Once the job is done, the wand thing comes back out - the hook is detached, without sparks as their is an alternative path for the electricity through the wand, and then the wand is slowly removed. Linemen are nuts!