
What to Do After Finding Hot Connectors on Overhead Power Lines (2017) [video] - camtarn
https://www.youtube.com/watch?v=piQpLL5nD18
======
camtarn
This 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.

~~~
lisper
It 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.

~~~
dreamcompiler
Okay I've actually flown helicopters, and it's not that hard. Harder than
fixed-wing, but much easier than standing on a basketball.

~~~
lovemenot
If I read your parent correctly, you need to compare standing on a basketball,
not with _flying_ a helicopter, but with precision hovering one.

~~~
dreamcompiler
Fair enough. Hovering is definitely harder than forward motion, because among
other things the tail boom acts as a weathervane during forward motion. But
hovering is still easier than standing on a basketball. I've done the former,
and I can't imagine even trying to do the latter.

~~~
foxyv
Are you rated for the Basketball? How many hours have you logged on the
basketball? /s

~~~
tylerl
I got my "single basketball on grass" rating a couple of years ago, and have
been meaning to schedule a checkride for my "single basketball on hardcourt"
endorsement for a long time, but honestly I don't know when I'd ever use it.

------
AWildC182
For 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)

------
kragen
I 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.

~~~
Declanomous
It 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.

~~~
qdcarnicelli
It'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.

------
scrumper
This 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
It'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.

~~~
p1necone
I chuckled at "Assuming a spherical helicopter".

~~~
deelowe
This is how you know the parent is an engineer.

~~~
function_seven
Nah, physicist. If parent was an engineer, he's just reference the row and
column from some table of helicopter capacitances. ("See p.34, table 7 for the
MD-500. The one in the video is a 530, but close enough")

~~~
deelowe
Good point.

------
docker_up
I 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
Yes, 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
The 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
Pretty 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
Ah, good point. Grandparent is correct. Carry on!

------
peterwwillis
Here's an article on the pilots/flying:
[https://www.verticalmag.com/features/highvaluecargo/](https://www.verticalmag.com/features/highvaluecargo/)

------
mkagenius
As 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
I 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
Yeah 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
underground is more resilient to damage but harder to do maintenance and
actually much more expensive at the distribution level

~~~
rtkwe
It 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.

------
jms703
What caused the line to overheat in the first place, requiring a splice?

~~~
LeonM
Usually (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
The 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.

------
fcbrooklyn
There 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)

------
jcims
Reminds 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.

------
paavoova
This 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
> 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.

------
floatrock
In 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
A) 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.

------
anonu
Don't you measure electrical resistance between two points? How is the guy
measuring resistance on the line at a particular point?

~~~
shaftway
If 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.

------
BooneJS
I 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!

------
dmritard96
Sometimes 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
I’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
Yes, being dead does hurt less than a papercut.

~~~
code_duck
I do not appreciate the useless dismissive statement. I’m talking about
something intense I’ve experienced personally, and you are being rude.

~~~
gambiting
Just because you are talking about it doesn't mean it automatically commands
compassion or respect, and I am not saying this to be rude.

------
modells
There's some great videos of installing spacers on multi-100kV live lines and
of the Bond villian tree-trimmers.

------
elorant
Couldn't we use something like that on wildfires for chopping down trees
quickly?

~~~
tgtweak
Like 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)

------
ur-whale
What what happens at 2:57 in the vid. Did you spot the large spark?

~~~
kiallmacinnes
I 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!

------
mkoryak
how much do those guys make?

------
trestletech
Came for the video, stayed for the comments.

------
hindsightbias
Multiple passes on 20 bolts on each side? Does it really have to be that
complicated?

~~~
NullPrefix
You 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
I 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.

