Interesting clip

[fc]

Interesting clip. http://www.glumbert.com/media/highpower

I guess you can say thank God he is not grounded.

 

[M. D.]

Thanks that was interesting to say the least.

 

[wbalsam1]

After a day of that work, I'd say "It's Miller Time!"

 

[tom baker]

The person who first thought of this type of HV work could not get anyone to let him try it.

 

[lowryder88h]

Clip

Clip

It maybe miller time for you but, I think I'll go home and change my underware, thank you very much!!! Great clip

 

[George Stolz]

That is an excellent clip.

"I say it's as as safe as crossing the street."

I'd have a different spin on that; it's as safe as crossing the street with C-4 strapped to your chest. There's no reason it should go off.

One curiousity I had - what causes the arcing between the helicopter and the line? The capacitance of the helicopter?

 

[raider1]

Great clip fc.

Makes me think I picked the right career move.

Chris

 

[benaround]

It will be the woman that will get him!!!!!!

 

[karl riley]

I would guess he is charging the helicopter (as a capacitor) to the voltage of the lines before getting in contact with it with his body. No?
Karl

 

[brantmacga]

I would guess he is charging the helicopter (as a capacitor) to the voltage of the lines before getting in contact with it with his body. No?
Karl

mmm hmmm.,,,,,,

 

[ron]

Great video. I've seen it on Cable before.
Antone know how it can be downloaded so I could keep it on my local PC for showing to my family members that don't have an internet connection?

 

[NoVA Comms Power]

... One curiousity I had - what causes the arcing between the helicopter and the line? The capacitance of the helicopter ...

My understanding is that it's caused by inductance, which creates the voltage differentials (and current) in everything near the high-tension conductor.

That's why the worker wears that conductive "Faraday suit" ... it conducts those induction-induced currents around him rather than thru him.

Apparently, those currents aren't actually life threatening ... but they are uncomfortable (remember the Van DeGraff generators in science class?)

It's the same reason why you never see birds sitting on HIGH voltage transmission lines; while "lower voltage" distro lines don't create enough of the effect to chase away the birds (or the POCO linemen who don't need to wear "Faraday suits" either).

 

[karl riley]

Nova, to continue the reasoning: the helicopter also has its faraday cage body, which protects the pilot. There is of course induced voltage with the counter-currents. But as I see it the purpose of the wire wand the guy is using is to bring the voltage of the helicopter up to equilibrium with the lines so that as he steps across there is no voltage gradient. No?

And what does hmmm mmm mean? Speak out, friend.

Karl

 

[tkb]

How do they get to the center line of the system.

The helicopter can easily get to the outer lines, but how do they get to the center line without crossing between phases?

 

[hardworkingstiff]

.... and I'm married too. (LMAO)

Great clip!

 

[mayjong]

saw it on cable (along with the whole show)
interesting thing was that the FIRST time it was ever done, nobody was sure what would happen... i mean, theory is one thing, but they weren't sure if the heli would drop from the sky (equipment short/failure). it was actually first done (i think in Africa) outside the USA , because they couldn't get clearance to do it, due to safety concerns. now it is the only way these lines are worked on.
would you have been the first to "try" it?!?!? not me!!!

 

[cowboyjwc]

I think the first time you see the arc they were actually taking it to ground with the wand until they could hook up the clamp. The second time may be because the rotor blades create static electricity and again I believe they are doing the same thing and basically discharging it.

 

[winnie]

I'm fairly sure that most of the arc is caused by the capacitive circuit formed between the line, the helicopter, and earth/other lines, combined with corona discharge current from the helicopter to the air around it, and again from there to the other lines or earth.

I estimated the capacitance of a helicopter as being equivalent to a sphere 3 meters in radius. This is larger than the body, smaller than the rotor disk, and of the wrong shape...but it should give an order of magnitude approximation. I got a value of about 330 pF. The 500KV current into a 330pF capacitance at 60Hz is about 60mA, more than enough to get your attention. That 60mA will be relatively constant current; it doesn't matter if you have 50 or 100kV to make an arc jump, or direct bonded contact with no voltage drop at all; most of the voltage drop is across the capacitor, and the capacitor is what limits the current.

I don't know how to figure corona discharge from a helicopter at 500KV

I did some looking; helicopters can charge up to very high voltages, but it looks like the current is less than 1mA even in really bad conditions. One interesting point which I came across but did not look into enough to confirm. It seems that most of the electrostatic current doesn't come from the spinning blades, but from other sources, eg. engine exhaust.

My guess: The capacitive current dominates the arc that we see. We see an arc when the circuit is made (closing the switch) and when it is broken, and at other times the same 60mA is flowing through the fat bonding cable. Just my best guess at the present time.

-Jon

 

[jaylectricity]

So the two wires this guy was shimmying along were the same phase just run in parallel? Just PM me the answer if you have it, I won't remember to check this thread.