I am so lost, anyone help?

[76nemo]

We had a tornado watch yesterday. It blew right by us, we were fortunate. Other counties around us got SLAMMED!!!!!!! They showed a helicopter hired by National Grid flying around with a huge "hoolhoop" test appartus slung 30' below the helicopter testing for fault conditions. What is this thing? I tried to look for pictures for you guys/gals on the net, yet to no prevail. Do any of you know what apparatus this could of been they were using to find faults? How does it work?????? I will continue to try to find pic's, but can any of you beat me to the answer on what that was? I am baffled, and that is nothing new. I am not all that familiar with utility work. The Grid guys here don't even wear full suits here, and that bothers me.
The helicopter flew over 50' above the lines. What the heck was this thing?????????????

Thanks in advance for your answers and knowledge. Always curious, always seeking knowledge. I am stumped on this one. Can someone fill me in:-?

 

[HawkEye_Pierce]

Giant coil that can pickup current?

 

[electricalperson]

maybe the helecopter was trying to find power lines that were off so the crews could fix them

 

[mivey]

Looking for bad insulators / arcing like you used to do with an AM radio?

 

[76nemo]

Still baffled,.....

Still baffled,.....

Mivey, that's very possible. I still can't find pictures, only articles. Here is a link, read the last paragraph.

http://www.wwnytv.net/index.php/2008/06/11/st-lawrence-county-resident-survey-storm-damage/

 

[76nemo]

Duhhhh, there it is. Read the last paragraph and then play John Friot's footage. The copter is the last thing shown in the footage. What the h*ll are they using???????????? How does it work? WTF is it?

 

[76nemo]

Did you all see the house torn in half? How it didn't burn is unbelievable. Maybe they lost power first,........

 

[hardworkingstiff]

Maybe it like the locator used for UG utilities? They put a tone on the conductor and if they lose the tone, go check out why?

Just a WAG.

 

[76nemo]

Maybe it like the locator used for UG utilities? They put a tone on the conductor and if they lose the tone, go check out why?

Just a WAG.

That high up above the lines,....no way. I always find things to stump me, but not like this one! I am begging for an answer. What the h*ll are they doing:-?

 

[chris kennedy]

They showed a helicopter hired by National Grid flying around with a huge "hoolhoop" test appartus slung 30' below the helicopter testing for fault conditions.

How can you say 'testing for fualt conditions'?

 

[gar]

080611-1833 EST

76nemo:

e = N df/dt

In other words the voltage induced in a coil is a function of the rate of change of the flux coupling the coil.

If a pair of wires in the transmission line are shorted together you have an excitation coil producing a magnetic field that is a function of the current flowing in the excitation coil. High current produces high flux density. Actually under normal load you have a magnetic field, but much lower intensity than from a short circuit. If this magnetic field is changing, which it is 60 times per second for a full cycle, then another coil in this field will have a voltage induced in it that is proportional to the field intensity and rate of change.

I think HawkEye_Pierce's suggestion is coirrect.

.

 

[djohns6]

If a pair of wires in the transmission line are shorted together ...

Then I believe you would have a fireball .

 

[gar]

080611-1934 EST

djohns6:

True for a dead short, but there may be faults causing abnormally high currents.

Where main lines branch at various points the fly over search may be the only easy way to search toward the fault location. In all probability these various branches may not be individually monitored for load current.

.

 

[djohns6]

080611-1934 EST

djohns6:

True for a dead short, but there may be faults causing abnormally high currents.

Where main lines branch at various points the fly over search may be the only easy way to search toward the fault location. In all probability these various branches may not be individually monitored for load current.

.

Your post raises a ton of questions with me , but so as not to appear arguementative , I'll let it go . I'm thinking about calling it a night early .

 

[KP2]

Its like a giant hot stick, or voltage pencil, or tick tester, or whatever you call them. I wonder if they can read a specific induced voltage or if it just BEEPS,

 

[cadpoint]

The Poco can usually ping down a complete circuit, they know what to expect in their complete service, with interpuption of this service, that's lost.
How else would one see a lost phase, ETC. Think of all the variables that could be involved.
Nice Thread, Gar!

 

[djohns6]

The Poco can usually ping down a complete circuit, they know what to expect in their complete service, with interpuption of this service, that's lost.
How else would one see a lost phase, ETC. Think of all the variables that could be involved.
Nice Thread, Gar!

What's " pinging down a circuit " ?

 

[gar]

080612-2059

djohns6:

I do not mind a discussion on this because I truely do not know what they are doing. I am conjecturing on a reason and what may be occuring. I was going to look at my power lines this evening with a small coil and see what I might observe, but my low range meter was not at home.

When I did some ground voltage measurements the other day I was seeing phase shift changes, harmonic changes, and of course voltage changes as various neighbors loads probably changed. Some of this could have resulted from primary line currents inducing a voltage in my voltage measurement, but I doubted this without experimental evidence.

.

 

[hardworkingstiff]

Maybe someone should just call the PoCo and ask?

 

[gar]

080613-1309 EST

Todays experiment a few minutes ago.

I used a one turn rectangular coil 12 ft x 30 ft located about 30 ft below my primary lines for my flux detector. Measured voltage with a Fluke 27 was 0.5 MV sometimes dropping to 0.4 MV. From previous posts I have from my perspective a 3 phase delta distribution system.

Same length of wire and I changed it to a loop 40 ft by 2 ft. New reading 0.1 MV. Less flux coupling in this case because of the smaller cross-sectional area, 360 sq-ft vs 80 sq-ft. The voltage ratio corresponds to this change.

Yes it is possible to get some idea of the current in the lines. Although I could have a highly balanced load and see less induced voltage than an unbalanced line of lower current. What I see with this coil is the net flux coupling to the coil.

.