Comparison of SafeGrid with XGSLab and CDEGS Results

Multilayer earth grid resistance for 60 m square grid

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 - XGSLab 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™ MALT 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 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.

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Easily design safe earthing systems in compliance with Standards.

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SafeGrid Earthing Software

Easily design safe earthing systems in compliance with Standards.

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