I am trying to understand ground current in a power distribution system.
The basics, of course, are simple: in the power grid, the "hot" wires carry high voltage, while the return path (the neutral wire) is connected to ground, so ground forms part of the circuit.
Some people seem to claim that this ground current is harmful. Be that as it may - I am not trying to argue about that question, but rather want to understand how ground current really flows.
The only source I could find was by Duane A.Dahlberg, and to be frank, I could not make heads or tails of it. Other than that, I have not been able to find any reputable source of information.
One of the claims I read was that somebody standing on the ground could experience a potential difference of 0.5 V between his right foot and his left foot. That seems very hard to believe.
I am most interested in how ground current would flow related to a 500kV overhead line, about 100 miles long.
Specifically, what I would like to know.
What voltage and amperage (order of magnitude) is the actual ground current? Obviously, in a 220kV line, most of the 220kV should go into the load. How much is lost on the actual wire, and, what is the voltage between ground on one end of such a transmission line to ground on the other end?
Does the ground current travel along the surface, or does it penetrate into the ground?
How does the type of material affect ground current (e.g., dry soil, rock, ground water, etc.)
Are there differences between AC and DC power lines with respect to ground currents?