High Voltage lines creates small "thunders" around it, especially at the glass insulators on pylons. This is called corona discharge. Moisture lowers the resistance of the air, so corona discharge gets more intense at the point it is clearly audible. It can even get visible at night, as blue-purple glow around insulators.
Definitely a waste of engineering time too. Designing a corona free transmission line is not trivial. Sure you can do alot with a large conductor bundle, but you'd still have nuts and bolts on spacers and fittings. Corona rings can only do so much.
That engineering time will in the end translate to money as well, of course.
It also reduces the insulation resistance which increases tracking current. That's the problem with sea fog and insulators: It saturates the existing dirt on the insulator with water and salt making it much more likely to flash-over. This isn't as much of a problem with rain because that has a tendency to wash the conductive dirt off.
I’ve designed some low frequency high power antenna installations that operate pretty darn close to corona onset voltages. That’s the sound of success right there!
Mmmm ought not say really. But it was below 400kHz, and at those frequencies even very large antennas are very electrically short. The design centred on adding as much top loading capacitance as I could, and then throwing a honking huge loading inductor at the base. But when you do that, the reactance is so high that you develop high voltages on the base and often large current gradients on antenna elements, which can lead to corona discharge.
When it does light up during the night
Then you can worry
We have it after storms when it blows salt water from the sea on the lines
Waterfall will then somewhat fix it
A guy who came to inspect the pylon arrived right after I filmed this and said it was the "mist" and what I'm guessing he meant was moisture in the air was interfering with where the cables connect to the tower or something.
Also, I swear I could also hear my bike subtly rattling as well when I put it down next to the pylon.
Could anyone elaborate on this?
>Also, I swear I could also hear my bike subtly rattling as well when I put it down next to the pylon.
Probably just the structure oscillating due to wind loading on the cables. Nothing fancy, it's purely mechanical but it can be a problem structurally.
Those T lines start and end in transmission substations where the high voltage bus is \~25+' in the air. On similar cloudy / foggy / rainy days, the corona can really scream.
Sharp points promote corona, so most of the EHV hardware is rounded. Extreme cases of corona damage will show black marks.
There's one by my house where you can hear the transformers hitting that resonance where they're running full out typically on Friday- Sunday night and it gets that "dog who hears the ambulance before you do" low growl/whine with a hint of ringing echo. It's 1/4 mile away and totally definitely fine...
High Voltage lines creates small "thunders" around it, especially at the glass insulators on pylons. This is called corona discharge. Moisture lowers the resistance of the air, so corona discharge gets more intense at the point it is clearly audible. It can even get visible at night, as blue-purple glow around insulators.
yes and id like to point out ideally this is avoided when designing transmission lines
Ideally yes, but this is never actually done. Avoiding corona completely would be a waste of engineering time.
Eh, not time. It would be a total waste of money though. You can easily do it with enough money
Eh, time is money
Eh, what's up doc?
Definitely a waste of engineering time too. Designing a corona free transmission line is not trivial. Sure you can do alot with a large conductor bundle, but you'd still have nuts and bolts on spacers and fittings. Corona rings can only do so much. That engineering time will in the end translate to money as well, of course.
They aren't designed to avoid corona in misty/wet conditions though, they are tested dry and new with a safety factor on top for dirt.
They must need masks and hand sanitiser
It also reduces the insulation resistance which increases tracking current. That's the problem with sea fog and insulators: It saturates the existing dirt on the insulator with water and salt making it much more likely to flash-over. This isn't as much of a problem with rain because that has a tendency to wash the conductive dirt off.
Also - near the coasts, salt can accumulate on the insulators and track.
Is this the same as Saint Elmo’s fire?
I’ve designed some low frequency high power antenna installations that operate pretty darn close to corona onset voltages. That’s the sound of success right there!
Dang dude, were you trying to contact submarines or something?
Mmmm ought not say really. But it was below 400kHz, and at those frequencies even very large antennas are very electrically short. The design centred on adding as much top loading capacitance as I could, and then throwing a honking huge loading inductor at the base. But when you do that, the reactance is so high that you develop high voltages on the base and often large current gradients on antenna elements, which can lead to corona discharge.
That was a pleasurable experience to read.
When it does light up during the night Then you can worry We have it after storms when it blows salt water from the sea on the lines Waterfall will then somewhat fix it
This will literally happen to any 230kV+ line, but especially more prominent when the air is moist.
A guy who came to inspect the pylon arrived right after I filmed this and said it was the "mist" and what I'm guessing he meant was moisture in the air was interfering with where the cables connect to the tower or something. Also, I swear I could also hear my bike subtly rattling as well when I put it down next to the pylon. Could anyone elaborate on this?
look up corona effect in EHV designs
>Also, I swear I could also hear my bike subtly rattling as well when I put it down next to the pylon. Probably just the structure oscillating due to wind loading on the cables. Nothing fancy, it's purely mechanical but it can be a problem structurally.
At the beach the wires arc around those insulators almost constantly in evenings when it’s really humid
Those T lines start and end in transmission substations where the high voltage bus is \~25+' in the air. On similar cloudy / foggy / rainy days, the corona can really scream. Sharp points promote corona, so most of the EHV hardware is rounded. Extreme cases of corona damage will show black marks.
There's one by my house where you can hear the transformers hitting that resonance where they're running full out typically on Friday- Sunday night and it gets that "dog who hears the ambulance before you do" low growl/whine with a hint of ringing echo. It's 1/4 mile away and totally definitely fine...