Substation Grounding Design (Soil Resistivity model-3 layers)
Substation Grounding Design (Soil Resistivity model-3 layers)
(OP)
Is it ok to modify the soil layered structure model data(soil resistivity measurment model)to obtain agreement with Fall-of-Potential(FOP)measuements?






RE: Substation Grounding Design (Soil Resistivity model-3 layers)
Please clarify your question.
RE: Substation Grounding Design (Soil Resistivity model-3 layers)
for modifying the comined soil model data to obtain agreement between Fall-of-Potential(FOP)measuements and simulated FOP?
RE: Substation Grounding Design (Soil Resistivity model-3 layers)
If you simulate the FOP based on the soil model and grid design, and then measure something different, it isn't clear what to do. It may mean that the grid was not constructed according to the design. It may mean that the original resistivity measurements were not correct or complete. How would you vary the soil model? Change the layer resistivities? Change the layer depths? Some combination?
RE: Substation Grounding Design (Soil Resistivity model-3 layers)
RE: Substation Grounding Design (Soil Resistivity model-3 layers)
To get a good FOP test, your remote current probe must be placed a distance at least 5 times the longest diagonal of your grid. This means fa 150'x 150' grid, the C1 probe is at least 1060 feet away. If you are closer, you won't get the flat area on our curve to indicate the actual impedance.
Most substations and grids are not in a virgin area They are surrounded by these other structures that can affect the results. So trying to modify your soil model to match a field test may be fun academically, but you're just comparing an approximation from a calculation to questionable test result. Which one is more accurate?? I no longer trust either.
It might be useful if you could run several tests on a virgin site and try to adjust the model to match.
We now verify our designs by impressing a voltage on the grid and measuring the step & touch potentials. I don't worry about trying to optimize the grid to save copper because by the time I bond all of the substation equipment, I already have more copper than the program claims I need.
RE: Substation Grounding Design (Soil Resistivity model-3 layers)
The curve we get from FOP measurements is smooth without any dip. This means there is no indication of metallic objects such as fences, pipelines, creeks,....
RE: Substation Grounding Design (Soil Resistivity model-3 layers)
RE: Substation Grounding Design (Soil Resistivity model-3 layers)