Q12569 : Using uniform soil model versus two-layer soil model in Right-of-Way
Question Using uniform soil model versus two-layer soil model in Right-of-Way
If one decides to use the two-layer soil model in order to improve the computation accuracy in Right-of-Way, the computation time can be unbearably long when Automatic Mode is selected. This is because the program will calculate the equivalent uniform soil resistivity for each region (even each section), even though some regions or sections have the same two-layer model, this because the equivalent uniform soil resistivity depends not only on the two-layer soil model, but also on the separation distances between conductors. Quite often, the separation distances between conductors are different from one section to another. As a result, the equivalent uniform soil resistivity needs to be computed for each region or each section. One way to improve this situation is to use Manual Mode. In this case, one needs to estimate three average quantities as shown on the screen, then get an equivalent uniform soil resistivity for the current region. Furthermore, you can apply this equivalent uniform soil resistivity to other regions, if appropriate.
On the other hand, keep in mind, for most practical studies, simply using the BOTTOM soil layer resistivity in the uniform soil mode, instead of using two-layer soil mode, usually produces the results which have sufficient accuracy.