Detecting leaking current with a torch - GIF

[ToolTalkBot]

Detecting leaking current with a torch.




Previously:

Closing a high voltage disconnect - GIF
Cutting a high-voltage power line - video
Engaging high voltage disconnectors - GIF
High voltage fuse removal tool - photo
Installing high-voltage cable spacers - GIF
Laying high voltage underground cable - GIF

[nova_robotics]

I've seen this before and still don't understand it. If the flame triggers an arc, would that not be incredibly dangerous for the person holding the torch?

[imohtep56]

I've seen this before and still don't understand it. If the flame triggers an arc, would that not be incredibly dangerous for the person holding the torch?

There are at least 3 people in that area so they are not powered up. Most likely have an extremely low current (in the milliAmps) high voltage supply feeding the circuits.
Remember, Tesla demonstrated that it's current that kills, not voltage...

[nova_robotics]

There are at least 3 people in that area so they are not powered up. Most likely have an extremely low current (in the milliAmps) high voltage supply feeding the circuits.
Remember, Tesla demonstrated that it's current that kills, not voltage...

The amps not volts debate is an old wives tale and bordering on just plain wrong. It's kinda right, but it's mostly wrong. It's like saying it's the width, not the length that gives you the square footage of a house. That and combined with the capacitance of that massive system and I don't even think it's possible to limit the amps. Something else has to be going on.

What does damage is the total energy delivered to your body, same with x-rays, or heat, or a punch from a boxer. The energy delivered to tissue measured in Joules is the problem. When they jumpstart somebody's heart with those AEDs (automated external defibrillator), or in medical shows before they yell "CLEAR!" it's always measured in Joules not amps. So for electricity that means volts multiplied by amps integrated over time. And unless you're a walking superconductor you can't have amps without volts. So saying it's only the amps doesn't really mean anything.

But even then if you have a current limited power supply, lets say 100 kV with a series resistor limiting current to a few nanoamps. On the surface that would not be a problem. But given the enormous size of that equipment, particularly those spherical conductors, the capacitance will be quite large. So even with the power supply disconnected the capacitance will be able to discharge quite a large number of amps. So you have both volts and amps for a large amount of delivered energy regardless of the power supply.

The energy stored in a capacitor is E = 1/2 C * v^2, where C is the capacitance and v is voltage. 10 Joules of delivered energy will knock you on your butt and ruin your week, but in some cases can be fatal. The breakdown of air isn't linear, but in general can be (badly) approximated to 30 kV/cm. If they're more than a few inches from those conductors it can be safe to say they're in the 100s of kilovolt range. Lets say 100kV, which is probably unrealistically low for what they're doing. If we need 10 Joules that means we need a measly nanoFarad of capacitance in that system to be able to store 10 Joules at that voltage. It is highly likely that there is far more capacitance in that system than a nanofarad.

[nova_robotics]

Okay so I just looked it up. The flame doesn't detect voltage or cause a discharge. The high voltage causes air currents, which can be seen when the flame dances around. It's just a bad way of seeing air currents.

[tlnixon]

Kind of reminds me of the movie "GhostBusters!" LOL!

[BuffaloJohn]

I've seen this before and still don't understand it. If the flame triggers an arc, would that not be incredibly dangerous for the person holding the torch?

So much to unpack - here goes.

This facility looks like a High Voltage facility. The building is a big space, there are lots of insulating paths and lots of insulators. I did an image search and this indeed is what I thought, though it is more. The image below is from


"Converter that transforms alternating current into direct current at Radisson substation"

which you can read about on:

Extra-High-Voltage Transmission | 735 kV | Hydro-Qu?bec
Quebec Hydro has 735kV power transmission lines. On that page they state that one of those lines is equal to four 315kV lines, which they call out as reducing the number of towers required. Why is that? Ohm's law. The power lost on the transmission line is I*I*R (square of the current) Power transmitted is V*I, so if you double the voltage and keep the current the same, you have the same lost power.

Another image that was found was from
https://www.electric-test.com/news/1...-60688515.html
which talks about a 1100kV Converter Transformer Valve ...

That is a testing facility and looks very similar to the video, could be the same place (look at the walls, both the exterior on left and interior on right).

These folks test high voltage stuff.

As for the torches, this is a little suspect to me. The facility is powered on and the purpose of the torch would be to identify voltage fields. The lit torch emits hot gas and burning byproducts - however, the torches don't hold a blue flame which is indicative of spillage of fuel so that it is not evenly mixed with air before burning.

Burning (combustion) requires three things - fuel, oxygen, and heat. If you control the three, you can make an optimal combustion - which in the case of the torch would be the hottest flame, which is blue. If you don't mix the fuel and air, burning still requires enough air for the chemical reaction of burning to occur. Letting the air come from the around the hot expelled fuel means that the fuel and air will mix less optimally and the flame will be yellow and sooty (incomplete combustion of hydrocabons can mean that some of the carbon is NOT turned into CO2 but just C).

Combustion is therefore classified as exothermic combustion or endothermic combustion. There is a difference between the reaction and the combustion style. While all combustion is an exothermic reaction, endothermic combustion requires that something be added outside of the reaction for the reaction to occur and continue - in this case the outside air is needed to sustain the reaction. For some, that is clear as mud, but think of it as the flame color - blue is exo, yellow is endo. There are plenty of examples of both exo and endo - a campfire is an endothermic combustion, for example (bonus points to you if you use that in your next campfire conversation).

If you watch the two guys, thay are shaking the torch, so they get yellow flames. That to me says that their torches are expelling extra fuel or (the guy on the right) it isn't adjusted right and is too "rich". Anyone who has used an oxy acetyeine torch has had to adjust the mixture to get the proper flame. Too "rich" and you get a yellow very sooty flame (acetylene is C2H2 so if you don't burn efficiently, you get lots of C), not enough fuel and the flame extends to far out and won't stay lit.

Is it a useful test? Maybe not so much, but it makes an internet video that people who don't know what is going on will think is something else.

High voltage fields like to ionize atoms, so walking about inside the high voltage chamber with a source of conductive gases, means that the high voltages present will find a path to ionize the contaminants and make a flash (burning off the unused fuel and soot).

I think they are doing it for show. It is NOT testing for gas leaks, that would be incredibly stupid. Enough leaking fuel mixed with the air of the building would be a catastrophic explosive danger - witness the various yt videos of the folks who pour gasoline on a fire and then light it after a bit - boom...

[gutofabbro]

Hello everyone!

Sorry to disapoint you all. But this test has nothing to do with current ou voltage.
It works to find gas leaking from the cooling system.
Normally they use the Sulfur hexafluoride, that is a great cooling and isolant gas.
These kind of chamber uses this gas to cool down the whole system, in a closed circuit.
As the SF6 is a non-combustible gas the flames will extinguish, if there was a leak in the chamber.
There are some gas detectors to do it, but this old way is cheaper.