Table of Contents
Overview Of The Comparison
We have benchmarked our SafeGrid Earthing Software results for a 60 x 60 m grid against well-known software XGSLab™ and CDEGS™.
We show that the results for grid resistance in multilayer soils up to 5 layers are virtually identical (maximum +0.59 % and +0.77 % difference respectively). The results have been analysed.
Common Inputs
Soil models – see the table below.
Grid dimensions – 60 x 60 m square grid consisting of 10 m meshes.
Depth of burial – 0.5 m
Conductor diameter – 10 mm (78.54 mm2)
Conductor material – Copper, annealed soft-drawn (100 % conductivity)
Table 1 – Common Input Values
| Two Layers | Three Layers | Four Layers | Five Layers | |||||
|---|---|---|---|---|---|---|---|---|
| Layer | p (Ωm) | h (m) | p (Ωm) | h (m) | p (Ωm) | h (m) | p (Ωm) | h (m) |
| 1 | 100.00 | 2.00 | 100.00 | 2.00 | 100.00 | 2.00 | 100.00 | 2.00 |
| 2 | 50.00 | Infinite | 50.00 | 6.00 | 50.00 | 6.00 | 50.00 | 6.00 |
| 3 | 200.00 | Infinite | 200.00 | 15.00 | 200.00 | 10.00 | ||
| 4 | 75.00 | Infinite | 20.00 | 15.00 | ||||
| 5 | 300.00 | Infinite |
Results
SafeGrid Versus XGSLab™:
| Soil Model | Rgrid - SafeGrid | Rgrid - XGSLab | Difference |
|---|---|---|---|
| Two Layers | 0.494 Ω | 0.4911 Ω | +0.59 % |
| Three Layers | 1.034 Ω | 1.033 Ω | +0.1 % |
| Four Layers | 0.753 Ω | 0.7509 Ω | +0.28 % |
| Five Layers | 0.797 Ω | 0.7963 Ω | +0.09 % |
SafeGrid Versus CDEGS™:
| Soil Model | Rgrid - SafeGrid | Rgrid - CDEGS | Difference |
|---|---|---|---|
| Two Layers | 0.494 Ω | 0.4902 Ω | +0.77 % |
| Three Layers | 1.034 Ω | 1.03 Ω | +0.39 % |
| Four Layers | 0.753 Ω | 0.7491 Ω | +0.52 % |
| Five Layers | 0.797 Ω | 0.7927 Ω | +0.54 % |
There is excellent agreement between the results obtained using SafeGrid with both XGSLab™ GSA and CDEGS™ MALTZ software which are given here and this is for all soil models up to 5 layers.
It is noted that the value of grid resistance given by SafeGrid are in all cases slightly higher than those given by the other software (maximum +0.59 % and +0.77 % respectively) and this is because SafeGrid considers the series impedance of the grid conductors and not that they are ideal conductors nor that the grid is equipotential.
The SafeGrid multilayer calculations and results are equivalent to the frequency domain algorithms namely XGSLab™ GSA_FD and CDEGS™ MALTZ.
Extensively Tested
ELEK has performed extensive validation of SafeGrid through comparisons and current injection tests for design projects over the past 10+ years.
