How come???

[HayZee518]

During a driving rain storm, I mean sheets of rain, how come high voltage lines don't arc around the insulators to ground? In substations potential transformers are connected between lightning arrestors and the high lines. Standing about 14 inches high, how come these don't arc around the PT to ground?

[pushkins]

That's a great question and one I have asked before, the answer I got was that there is never a continuous "sheet" of water in other words the drops of water are separated by enough space that the electrical current cannot jump from drop to drop, that as well as the movement of the drops (between 7 and 18mph not wind assisted the speed increases with larger droplets) makes it much harder for the conductivity.

[HayZee518]

Hv

I don't see how that's possible because 345KV will jump a three foot gap in free air. How's an insulator skirt of a few inches gonna stop that?

[pushkins]

but not all voltage "jumps", a stun gun for example if you move the two little pins far enough apart it fails to work. A 4.5 million volt stun gun will not have an electrical arc if the pins are say 6" apart but it works very well at 3".
Or for that matter a spark plug lead if you hold it back from the end of the plug and turn over the motor you can move the lead closer or further away to stop or start the jump.

[Centurian]

How come

could you say that rain water is distilled water,..so it does not conduct
Since distilled water is purified and does not contain any impurities, it is unable to conduct electricity. Water molecules on their own have no charge and as a result they cannot swap electrons. Without the swapping of electrons, electricity is unable to travel through distilled water.

[HayZee518]

rain water

but rain water is not pure!
since it is traveling through air which is ionized, its picking up traces of carbon dioxide which if dissolved in water produces carbonic acid. hydrogen which is also in air results in hydrochloric acid.

[Speedbump]

It is true that rain water has no hardness (calcium, magnesium) and has a PH of around 5.5. It's TDS would be very low. I'm not sure about the distilled water theory, but it makes sense to me. If it weren't true, we would have a bunch of charred telephone poles. I can tell you that a Crow coming in for a landing on the high tension wires will disappear when he touches two of them.

Then there's Lightning. We can get into some really heated discussions about the theory behind that. Then to make it even worse, we could get into proper grounding for an Amateur Repeater like I have at my house.