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How to model conductors surrounded by additional substance using SafeGrid

Model the effects of Bentonite, Marconite or equivalent enhancement materials surrounding buried earthing conductors.

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Problem

 
To model the influence of an additional substance surrounding the conductors of a buried earthing system on grid resistance, touch and step voltages.
 

Solution

 
Treat the actual buried conductor and surrounding substance combined as a buried conductor of an equivalent (calculated) radius.
Figure 1 Earthing grid parameters with conductor surrounded by an additional substance.
Figure 1 Earthing grid parameters with conductor surrounded by an additional substance.
Figure 2 Earthing grid parameters with conductor surrounded by an additional substance.
Figure 2 Earthing grid parameters with conductor surrounded by an additional substance.

Approximate analytical equation

Formulae

 

Where

Where Formulae

Example

Example Formulae

Formulae2

Model in SafeGrid under Design Settings

Figure 3 Equivalent conductor radius modelled in SafeGrid under Design Settings.

Reference

[1]  Kurtovic, M. and Vujevic, S. “Earthing grid parameters with conductor surrounded by an additional substance.”, IEEE Transactions, 2000