Why don't high voltage transmission line conductors flash off to the grounded metal tower framework in a heavy rain storm? What keeps the rain water that's all over the insulators from providing a path to ground?
Thanks, Perion
Why don't high voltage transmission line conductors flash off to the grounded metal tower framework in a heavy rain storm? What keeps the rain water that's all over the insulators from providing a path to ground?
Thanks, Perion
The shape of the elements which make up the insulator does the job. The water can't make a continuous path to ground. If the insulator were of a plain flat construction, there could be a flashover. The shape also makes the path to ground along the insulator surface longer while keeping the overall length of the insulator a little shorter. An electrical arc will track along a surface (even a dry surface) easier than it will through air. For example, for electrical clearance at 5kv you may need 3" through air, but you'd need 6" across any surface.
Check this out.
The two dimensions are formally called strike distance and creep distance.
?s falke
"Frank" wrote ...
On Fri, 6 Feb 2004 10:07:46 -0500, "Perion" Gave us:
Perhaps it's the fact that water is not conductive.
Idiot, rainwater IS conductive. It has impurities.
Charles Perry P.E.
What else would you expect from DimBulb.
He's now going to rant on about how he was misquoted, or that air density (or some other lame excuse) negates his silly statement.
On Fri, 6 Feb 2004 21:57:33 -0500, Keith "Tard Boy" Williams Gave us:
You're an idiot.
Water is not conductive. Water... *WITH* impurities is.
I never said it wasn't.
Hey, KeithTard... Fuck you!
You should have read the question before posting then. He asked about flashovers from RAIN.
Charles Perry P.E.
Umm, DimBulb, the issue was *rain* water. As I predicted, you'd shift goal-posts and claim that you didn't say what you *clearly* did. Yes, everyone is after you. ...and with good reason.
Yes, you did DimBulb.
Just to refresh your feeble memory: The OP's question was:
To which the Dimest-of-DinBulbs *directly* answered:
So, yes you did say that *rain water* is not conductive. ...and once again showed that you're as Dim as they come.
Sorry girl. You're not my type. Try your sheep.
| Why don't high voltage transmission line conductors flash off to the grounded | metal tower framework in a heavy rain storm? What keeps the rain water that's | all over the insulators from providing a path to ground?
I've seen it happen. But that was freezing rain so I suspect it made a better path by sticking some ice on there along with dirt that may have built up over the insulator. I believe it was a 69 kv line.
Water not conductive?!? What the hell?!?
Time to flush the dark matter again!!!!
Idiot, rainwater IS conductive. It has impurities.
Charles Perry P.E.
On Fri, 6 Feb 2004 23:13:38 -0500, "Charles Perry" Gave us:
No. He asked why rain doesn't make a conduction path on an insulator. It doesn't have to flash to leak.
On Fri, 6 Feb 2004 23:47:06 -0500, Keith R. Williams Gave us:
Come find me then, wussy boy. We'll see who's dick get knocked in the dirt.
On Sat, 7 Feb 2004 08:13:49 -0600, "Me" Gave us:
It takes a true Usenet retard to top post, and be wrong at the same time.
Why then did you answer, incorrectly, that water is not conductive (everything is)?
Wiggle more worm.
Are you always so paranoid, DimBulb?
Yes - thanks for the reply. I see how the geometry and construction would minimize the possibility for rain driving in most directions. Wouldn't unpredictable swirrels of wind driven rain be able to form a conductive path? Also, it seems that for the case where there's a very heavy dew that condensation could coat the surfaces enough that there could be a continuous path though to ground. Is that true? Or is the resistance to the conductive frame still somehow kept extremely high even though the surfaces might have a thin film of dust laden water on them from dew?
Thanks, perion
On high-voltage cables (transmission lines) you can actually hear a faint 'crackling' sound when there is a lot of moisture in the air. I don't think dew is a problem for flashover, otherwise there'd be flashovers all the time. Does dew even form on the underside of an object? HV insulators are designed with the elements in mind. They take into account that they will need to withstand rain showers. That doesn't mean that there isn't the occasional situation where enough rain can cause a flashover.
high probabalitly that anything that gets by the design is heated from short quick flashovers which vaporizes water, and the high temp steam dissipates, removing the mositure path.
I have a 125kv line near my house and it is always popping and sizzling from moisture. FPL says it is supposed to act like that.
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