Grounding Design Calculations – Part Seven


I indicated that the Earthing Systems Design Steps process has (3) main steps:





Earthing Systems Design Steps

A grounding system design process has (3) main steps:


  1. Data Collection,
  2. Data Analysis,
  3. Grounding Design Calculations.







And I explained the first step: Data Collection in the following Articles:





I explained the second step: Data Analysis in the following Articles:



And I explained What we are going to design for grounding system in any building in the following Articles:







And, in Article 
Grounding Design Calculations – Part One ", I indicated the following:




Grounding System Design Calculations according to type of the building

The procedures for performing the Grounding System Design Calculations can differ slightly according to the type of the building as follows:

  1. Domestic, commercial and industrial premises,
  2. High and medium voltage electricity substations.








First: Domestic, commercial and industrial premises

We mean by domestic, commercial and industrial premises, all installations up to 1,000 V ac and 1,500 V dc - between phases, with some minor exceptions.






And I started discussion for Methods of Grounding Design Calculations of Domestic, commercial and industrial premises as follows:





Methods of Grounding Design Calculations

There are many methods can be used for performing Grounding System Design Calculations But the common methods are:

  1. Equations Method,
  2. Nomographs Method,
  3. Excel Spreadsheets Method,
  4. Tables Method,
  5. Online Earthing Calculators Method,
  6. Software Programs Method.







In this Article and Article 
 Grounding Design Calculations – Part Two ", I explained the first method of grounding design calculations: Equations Method and solved examples.



And I explained the second method of grounding design calculations: Nomographs Method in Article 
Grounding Design Calculations – Part Three".



Also, I explained the third method of grounding design calculations: Excel Spreadsheets Method in 
Grounding Design Calculations – Part Four ".



And I explained the forth method of grounding design calculations: By using Tables In Articles 
Grounding Design Calculations – Part Five " and " Grounding Design Calculations – Part Six ".



Today, I will explain the fifth method of grounding design calculations: Online Earthing Calculators Method.



You can preview the following Articles for more info:








Fifth Method: Online Earthing Calculators Method






Online Earthing Calculators Method

In this method, I will introduce some good online earthing calculators that can help electrical designers in grounding design calculations. I choose the following (3) online earthing calculators providers:

  1. LPI Earthing Calculator,
  2. Loresco Earthing Calculators,
  3. Electrician2 Grounding Calculators.


These (3) earthing calculators providers provide (6) online earthing calculators that will be explained herein.






Important

Before using any online earthing calculator, you must check its compatibility with your local codes and standards.






First: LPI Earthing Calculator

This, user friendly, earthing calculator allows you to estimate earth system resistance based on IEEE and other international earthing/grounding standards.  






1- Calculator sections

This calculator includes (3) different sections (see fig.1), they are as follows:

  1. Configurations Section,
  2. Parameters Section,
  3. Results Section.


Fig.1: LPI Earthing Calculator








1.A Configurations section

In this section, the user must select the configuration applied in his design from the following (5) configurations (see fig.2):

  1. A Single Vertical Rod,
  2. Horizontal Conductor With (Or Without) Vertical Rods,
  3. Horizontal Grid With (Or Without) Vertical Rods,
  4. More Than One Horizontal Conductor Radiating From A Single Rod,
  5. LPI Chemical Ground Rod.




Fig.2: Configurations section








1.B Parameters Section

This section includes (3) parameters category (see fig.3) as follows:

  1. Soil Category,
  2. Products Category,
  3. Layout Category.



Each category's parameters differ according to the selected configuration from the configurations section.



Fig.3:Parameters Section


1.B.1 Soil Category


Fig.4:Soil Category

It includes the resistivity parameter (Ωm) which can be inserted by one of the (2) following methods (see fig.4):

  1. Selection from the drop down menu that includes standard resistivity values based on table C2 in The Australian Standard AS1768-2007 (see fig.5), or
  2. Writing custom resistivity value by editing the blue underline value (below the drop down menu). 



Fig.5: Table C2 in The Australian Standard AS1768-2007



  • No changes in the soil category happen while changing from configuration to another.
  • Soil resistivity must be between 0.2 and 100,000 Ωm.



1.B.2 Products Category


  • It includes dimensions parameters for different products, these parameters can be inserted in the calculator by editing the blue underline values for each parameter.
  • The products included in the product category changes with changing the selected configuration from the configurations section as in below table:


Configuration
Products
in Products Category
A Single Vertical Rod (see fig.6)
Rod
Horizontal Conductor With Vertical Rods (see fig.7)
Rod
Tape
wire
Horizontal Grid With (Or Without) Vertical Rods (see fig.7)
More Than One Horizontal Conductor Radiating From A Single Rod (see fig.7)
LPI Chemical Ground Rod (see fig.8)
ChemRod



Fig.6



Fig.7

Fig.8

  • To activate/deactivate a product in multi-products category, you must on/off the button beside the product name (see fig.9).




Fig.9


  • For the following configurations:

  1. Horizontal Conductor With (Or Without) Vertical Rods,
  2. Horizontal Grid With (Or Without) Vertical Rods.


You can perform the calculations with or without using vertical rods (see fig.9); this is done by on/off the button beside the rod product.

  • For the following configurations:

  1. Horizontal Conductor With (Or Without) Vertical Rods,
  2. Horizontal Grid With (Or Without) Vertical Rods,
  3. More Than One Horizontal Conductor Radiating From A Single Rod.


  • Activation of tape product will deactivate the wire product and Vice versa (see fig.9), since only one product (tape or wire) can be used in these configurations.

  • Every product will have different dimensions parameters as follows:


Product
Dimensions Parameters
Limits
Rod (see fig.6 & 7)
Rod diameter (mm)
must be between 10 and 60 mm (also depends on hole diameter)
Rod Length (m)
must be between 1 and 30 m
Tape (see fig.7)
Tape width (mm)

must be between 10 and 100 mm
Tape thickness ( mm)
must be between 0.5 and 10 mm
Wire (see fig.7)
Area of wire (mm2)
must be between 30 and 500 mm2
Chemrod (see fig.8)
Selection of length to be 2 or 3 meters
Selection between vertical or horizontal Chemical Ground rod

The dimensions parameters in above table can be inserted in the calculator by editing the blue underline values for each parameter.



1.B.3 Layout Category


  • It includes dimensions parameters for different Layouts, these parameters can be inserted in the calculator by editing the blue underline values for each parameter.
  • The layouts included in the layouts category changes with changing the selected configuration from the configurations section as in below table:


Configuration
Layout
In Layouts Category
A Single Vertical Rod (see fig.10)
Rod Hole for Compound
Horizontal Conductor With Vertical Rods (see fig.11)
Rod Hole for Compound
Horizontal Conductor
Trench for Compound
Horizontal Grid With (Or Without) Vertical Rods (see fig.12)
Rod Hole for Compound
Grid
Trench for Compound
More Than One Horizontal Conductor Radiating From A Single Rod (see fig.13)
Rod Hole for Compound
Radial
Trench for Compound
LPI Chemical Ground Rod
No Layout




Fig.10


Fig.11


Fig.12


Fig.13


  • To activate/deactivate a layout in multi-Layouts category, you must on/off the button beside the layout name.
  • For the layout of configuration "Horizontal Conductor With (Or Without) Vertical Rods", The Horizontal Conductor layout can't be deactivated.
  • For the layout of configuration " Horizontal Grid With (Or Without) Vertical Rods", The Grid layout can't be deactivated.
  • Also, for the layout of configuration " More Than One Horizontal Conductor Radiating From A Single Rod", The Radial layout can't be deactivated.

  • Every Layout will have different dimensions parameters as follows:


Layout
dimensions parameters
Limits
Rod Hole for Compound (see figs. 10,11,12 & 13)
Hole diameter (mm)

must be between 10 and 500 mm (also depends on Rod diameter)
Hole Length = Rod Length (m).

Horizontal Conductor (see fig.11)
Buried Depth (mm)

must be between 100 and 10,000 mm (also depends on depth of trench compound)
Length of Horizontal Conductor (m)
must be between 1 and 100 m (also depends of number of Rods)
Number of Rods
must be a whole number between 2 and 5 (also depends on Length of Horizontal Conductor)
Grid (see fig.12)
X Length of Grid (m)

must be between 1 and 100 mm (also depends on number of grid conductors in X axis)
Y length of Grid (m)

must be between 1 and 100 mm (also depends on number of grid conductors in X axis)
Number of Grid elements in X axis

must be whole number between 2 and 100 (also depends on grid length in X axis)
Number of Grid elements in Y axis

must be whole number between 2 and 100 (also depends on grid width in Y axis)
Buried Depth (mm)

must be between 100 and 10,000 mm (also depends on depth of trench compound)

Number of Rods
must be whole number between 1 and 100
Radial (see fig.13)
Selection between "360° Full" and " Crows Foot (3 Radials over 120°)"
Length of Radial (m)

must be between 1 and 100 m
Buried Depth (mm)

must be between 100 and 10,000 mm (also depends on depth of trench compound),
Number of Radials

must be whole number between 3 and 10
Number of Rods
must be whole number between 1 and 100
Trench for Compound (see figs.11,12 & 13)
Compound Layer Height (mm)

must be between 10 and 500 mm (also depends on buried depth of horizontal element)
Width of Trench (mm)

must be between 100 and 500 mm
Depth of Trench (mm)


  • The dimensions parameters in above table can be inserted in the calculator by editing the blue underline values for each parameter.








1.C Results Section

This section includes (3) results tabs (see fig.14)as follows:

  1. System Only,
  2. With Reslo,
  3. With Grip.


RESLO (Ground Enhancement Compound) and GRIP (Ground Resistivity Improvement Powder) are used in earthing systems to reduce soil resistivity adjacent to earth system electrodes so as to reduce the resistance of the earth system.


Fig.14


  • Genrally the two result values will appear in each tab:

  1. R range,
  2. R Typical.


What is the R range?

Formulas provided in earthing standards assume perfect contact between the buried earthing conductor and the soil.  The result is a theoretical best-case scenario.  In real world applications it is generally found that perfect contact is not possible, and the measured result can in fact exceed this calculated best-case scenario by a factor of 10 or more.  The “Range” given in the LPI Earthing Calculator provides a lower limit (the theoretical best-case scenario) and an upper limit or worst-case scenario for a given soil type.


What is R Typical?

Based on installation experience and careful field testing, the LPI Earthing Calculator is also able to provide a very useful “Typical” result which shows the likely result for typical conditions seen in the field.

  • Generally the earth Resistance value appear in the system only tap without using RESLO and Grip materials
  • If using layouts "Rod Hole for Compound" or/and "Trench for Compound", the earth resistance value (after enhancement) will appear in the "With Reslo" tab or in the "With Grip" tab according to the used material for enhancing the erathing resistance value.
  • Also, the number of bags of Reslo compound or/and the numbers of kits of Grip powder will appear in each corresponding tab.
  • Calculations in System only tab are based on the rules in below fig.15.


Fig.15

  • Calculations in "With Reslo" and "With Grip" tabs are based on the rules in below fig.16.


Fig.16








2-LPI Earthing Calculator's Using method

The method of using this calculator is working left to right as follows:

  1. Select the configuration of your earthing system from the configurations section,
  2. Edit the dimensions and other parameters in Parameters section,
  3. In Results section, Results are given for the theoretical best-case scenario (as per the standard) as well as likely real-world values as typically seen in the field.







You can use the LPI Online Earthing Calculator by click on the link.






In the next Article, I will continue explaining grounding design calculations by using other Online Earthing Calculators. Please, keep following.


Post a Comment

Leave a comment to help all for better understanding