Transmission Tower Lightning Protection and grounding

[ek54]

Hi Guys,
I am a learning transmission design and would like some help with lighting protection.
My project involves 115 kV and 345 kV monopoles.
Using the EPRI AC transmission red book, table 6.10.2 provides equations for various tower footing resistance.
I used the CDEGS software to create a uniform model of the soil using resistivity data collected.
By calculating the tower resistance for each electrode configuration I can compare using the L1 applet which footing resistance will
provide less than 2 strokes per 100 km per year.
Is there a MatCAD file or any software available where I can enter data and get the resistances?
I created an excel sheet but would like to verify my outputs?
Are there diagrams of what these configuration should look like?
How are the vertical electrodes or horizontal radial wires connected to the tower based on this table?
Does each vertical/horizontal connect to the tower through seperate conductor?


Thank you.

 

[shamsdebout]

Very good question and unfortunately my response will probably not be commensurate in technical content.

When I think of lightning protection what comes to mind is providing a way to dissipate lightning discharges and surges into the ground. And based on my knowledge we will use conductors connected to electrodes to ensure the path to the ground.

I would think one of the manufacturers of lightning protection equipment may assist, such as Thompson lighting protection. I think they would have some experience with this type of installation and would probably have some diagrams.

To your first question, unfortunately I do not know of any such file.

Based on what I understand if the rods are interconnected then the intent of having a path from the tower to the earth would be realized.

 

[cranky108]

Most of us use steel shield wires, which follow the transmission line. These are tied to ground rods at the base of the tower. The grounding conductors are typically copper or copper coated steel to direct the lighting stroke to ground.
The conductors them selves are insulated from the tower, but will typically include a lightning arrester at reflection points along the line.

On wood poles there is a plate or wrap on the bottom of the pole, and sometimes a driven ground rod.