"Jim Lux" wrote
...
Szczepan Bialek wrote:

"Static electrical charge can build up to high values".

It take place during transmmiting.
Without grounding do not work.

I simply want to know "the value of the DC current".

Would that be the so-called "fair weather current" about 1 pA/square
meter?

It is flowing all the time. We are interesting in the transmissing time.

Obviously, a big metal tower is going to perturb the local field, so a
tower with a cross section of 1 square meter is going to have a current a
lot bigger than 1pA.

But probably not microamps.

OTOH, a big tower could have substantial capacitance to ground.. I don't
recall off hand what the capacitance of a isolated cylinder is..
I seem to recall that for a rod with lengthdiameter, it's something like
50pF/meter.

So, a 100 m tower will be 5000 pF.

Say the current is 1000 pA.

In one second, the voltage would be 1E-9/5E-9 = 0.2V

In a minute, 30V
In 10 minutes, 300V..

etc

It is a free energy .

Probably not enough to charge to voltages quickly enough to be a problem.

Tribocharging from dust and other particulates blowing in the wind is a
LOT faster and a bigger problem.

It works in the both directions. Charged tower lose charges.
S*