MODELING FOUNDATIONS IN WinIGS
MODELING FOUNDATIONS IN WinIGS
(OP)
Does anyone know how to model a foundation in a substation using WinIGS. I am designing the grounding system and get very different results depending on how I model the foundation. I'm unsure if I should use the re-enforced concrete block electrode(electrically isolated since we will not connect them), or a civil structure (as in the WinIGS example). The foundations in the substation are steel re-enforced concrete and we will not be tying them in with the grounding system. Thanks for any feedback






RE: MODELING FOUNDATIONS IN WinIGS
You should speak to Dr. George or Dr. Sakis at Univ. of Atlant(Georgia Institute of Technology), they own the company that sells these softwares. They are very good at responding emails.
RE: MODELING FOUNDATIONS IN WinIGS
RE: MODELING FOUNDATIONS IN WinIGS
RE: MODELING FOUNDATIONS IN WinIGS
RE: MODELING FOUNDATIONS IN WinIGS
Also consider that although the rebar is not deliberately tied to the ground grid, there is usually grounded equipment bolted to the slab, or at least sitting on it.
RE: MODELING FOUNDATIONS IN WinIGS
Jghrist,
"There will seldom be critical step- or touch-voltages around a slab foundation, so high accuracy is not usually important."
I have learned grounding by reading your posts here and they have been excellent. Some how the above phrase is not getting to me. Let me see if I got it right. Slab is a equipotential surface and besides it is a copper mesh where current is flowing during a fault and potential exists.
When somebody is standing besides the slab there is certainly difference in potential but how can we be sure that it may not be critical. If not step but touch potentaial can be significant, for example somebody holding a door and standing besides the pad during the fault, it could be a hazard.
Forgive me, if I am not very clear in my question.
Thanks
RE: MODELING FOUNDATIONS IN WinIGS
This may not always be the case, but if you model the slab even inaccurately, you can tell if the touch-voltage is close to being the worst case. If it is modelled and found to be much less than the worst case, you can safely assume that increasing the accuracy of the slab model will not make it the worst case.
RE: MODELING FOUNDATIONS IN WinIGS
RE: MODELING FOUNDATIONS IN WinIGS
If you are concerned, then specify that the anchor bolts be tied to the rebar. This will ground the rebar through the building/equipment ground. There are other ways to bond the rebar to the ground grid. It is an NEC requirement to use at least one foundation as a building ground electrode if it is available and meets certain requirements. Googling ufer ground detail will give some ideas on bonding.