StarmanJack
Electrical
- Jun 15, 2012
- 2
I am designing a grounding grid and have had no problems meeting step and touch potentials. I am having a hard time meeting the ground potential rise requirement of 5000 V. It is a small substation that is roughly 300x700 feet. The designs fault level is 25 kVA and I have a ground resistance currently of .25 ohms. The soil has a value of 80 ohm-m and is pretty consistant even as you go deeper. How can I reduce my GPR without making the grid overly big and without having to lay a ridiculous amount of conductor into the ground? Do some substations have grounding grids that extend far beyond the substation? If so, how much? I had one of our guys model the substation laying I think it was 2 inches of GEM material around the conductor but I didn't see that help much. When he put in grounding wells, I saw some improvement but not that much and I beleive thats due to teh soil not getting any better the deeper you go. Are there no nice solutions and you end up just laying a buttload of conductor into the ground?