Proceedings of the Sixth International Conference on Trends in Electronics and Informatics (ICOEI 2022)
IEEE Xplore Part Number: CFP22J32-ART; ISBN: 978-1-6654-8328-5
Design of Earthing Grid using ETAP
S.Sankara Kumar
S.Nandhini
Student, Department of EEE,
National Engineering College,
Kovilpatti, T amilnadu, India.
Assistant Professor,
Department of EEE,
National Engineering College,
Kovilpatti, T amilnadu, India.
sankarbe2002@yahoo.co.in
2022 6th International Conference on Trends in Electronics and Informatics (ICOEI) | 978-1-6654-8328-5/22/$31.00 ©2022 IEEE | DOI: 10.1109/ICOEI53556.2022.9777168
Abstract—
During ground-fault situations, the fault current will flow
through the system, in addition to that voltage gradients will be
created inside and in the surroundings of substation. It is
created among the structures and adjacent earth points and
also in the ground layer. The necessity forground grid study is
to provide safety and well-being of anyone exposed to the
potential differences that can exist in a station during a severe
fault. In this paper, the ground grid is designed in ETAP using
IEEE 80 & 2000/2013 methods. Three grids based on IEEE
method are designed, and the results are discussed in this
paper. In each method, the grids are designed in an optimized
way. The number of conductors and rods used in this design is
optimized for grids and cost wise also. Here the ground fault
current can modify by the user or from the bus through short
circuit analysis also updated. S ome of the factors that are
considered in a ground-grid study are Fault-current magnitude
and duration, Geometry of the grounding system, S oil
resistivity, Probability of contact, Body resistance, Standard
assumptions on physical conditions of the individual .
Keywords— ground grid,ETAP,ground fault current
1.
Introduction
In designing and construction of an electric substation,
one of the most important issues that must be considered is
designing of protective system to the earth. Flow of the earth
current, cause voltage gradients at ground level which can be
different parts of the earth and the reference (ground point).
For designing the ground grid, we have to consider the
parameters like step potential, touch potential, mesh
potential, Ground Potential Rise (GPR) and soil analysis.
Based on these potentials, the number of conductors and
rods to be used in the design and the method of designing
(IEEE / FEM) has to be considered. After these
requirements, the cost for the grids has to be taken into
account.
Ground Potential Rise (GPR) is the transient over voltage
that is created in the earth due to the current passing through
it. The difference in potential is formed on the surface of the
earth due to the conductivity level of earth and distance fro m
the current entry point.
In IEEE method, the default grid shape can be used based
on the requirement and cost. For examp le rectangle,
triangle,t-shape etc., In FEM methods , own shape can be
designed based on the grid requirement and cost. Based on
the soil and ground fault current, the grid design is
varied.Ground fault current decides the number of
conductors and rods to be used in the grid. Based on the
M .Willjuice Iruthayarajan
Professor, Department of EEE,
National Engineering College,
Kovilpatti, T amilnadu, India.
obtained GPR value and other potentials , the design has to be
modified. If GPR is greater than the recommended value,the
number of rods or conductors has to be increased. If it is less
than the recommended value, the design is successful. The
results obtained using this methodrises the overall cost of the
system. The additional cost for land has to be expended to
meet out the required safety measures.
1.1 METHODS OF GRID DESIGN
The methods of earthing grid design are

IEEE standard 80 & 665
1.1.1 IEEE standard 80 & 2000/2013

Empirical method.

Limited shapes only with vertical and horizontal
conductor.

Rod arrangements are not flexible.

It does not have any graphical plots.

Example: T-shape,
Rectangle shape.
L-shape,
Triangle
shape,
Umal et.al [1] discussed optimized earthing grid design
of a 132/ 33kV substation. Ground grid mesh is formed by
conductors in X and Y directions inside the soil at a depth of
0.5 m below the substation floor. Kaustubh et.al [2]
suggested simple analysis of grounding system performance
for given data and is able to recommend optimal design of
the grounding system in the given conditions and safety
constraints.Surya Hardi et.al [3] analysed the designing of
substation economically by considering the length of rod
conductor used. Various grid configurations built in models
utilized for designing are rectangular, T-shape and L-shape
models.
Kaustubh et.al [4] discussed about the grounding system
has to be safe as it is directly concerned with safety of
persons working within the substation. The key role is to
design safe and economical earthing systems for High
Vo ltageand Extra High Vo ltage substations.In paper [5], the
parameters of existing design of grounding grid of substation
are calculated with IEEE standard 80-2013 and some
techniques are discussed for increasing grounding system
safety.
For Calculat ing ground fault current, the impedance of
the line after fau lt may be considered asZf. For LG fault, one
phase ‘R’ is shorted to ground at the fault point, Remaining
healthy phases‘Y’ and ‘B’ are open circuited and has no
current; i.efault current is IR and IY = 0, IB = 0. The voltage at
the fault point F is VR = Zf IR.[6]
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Proceedings of the Sixth International Conference on Trends in Electronics and Informatics (ICOEI 2022)
IEEE Xplore Part Number: CFP22J32-ART; ISBN: 978-1-6654-8328-5
2.
Table 1 – Soil resistivity
GROUND GRID DESIGN - IEEE METHOD
2.1 GROUND GRID DESIGN PROCEDURE [7], [8]

Soil resistivity measurement and analysis.

Grid design (Conductors and rods).

Ground fault current calculation.

Calculations and result analysis.
2.2 GROUND GRID – 1(IEEE METHOD):
2.1.1 GROUND SOIL ANALYSIS

Measurements: Wenner four – pin method[9]

Probe distance and soil resistivity [10]

Calculate resistivity at each probe distance

Calculate top, lower layer resistivity, and top
layer depth

Calculate top, lower layer resistivity, and top
layer depth
In grid 1, we are using IEEE 80 & 2000/2013 method
[11].The shape of the grid is rectangle.Here we are using
three conductors in X direction and six conductors in Y
direction.We are using four numbers of rods.Here, in both
layer we are using mo ist soil which is having 100 oh m – m
resistance.After designing this specification in the grid, the
ground grid study is simulated.The results of analysis are
showed in Figure 2.3, 2.4 and 2.5.Ground grid 1 summary
with potential information and fault currents are shown in
Figure 2.6. Cost analysis and total number of conductors,
rods and length of conductors, rods are mentioned in figure
2.8. Figure 2.7 shows the grid 1 information with different
simulation.Based on the soil the resistance is varied and the
GPR is also varied and Rg is also varied.
Figure 2.1 - Wenner four – pin method
Figure 2.2 – Soil Analysis(IEEE-80 & 2000/2013)
It
consists
of
four
probes
fixed in a straight line at equi-distant points from each other. A constant
magnitude of current is passed through the outer two probes and the
potentialdrop V across the center two probes is measured [12] & [13].
Figure 2.3 – Grid 1 configuration for normal
simulation
2.1.2 GROUND GRID DESIGN

Area should be as large as possible

Properly arranged conductors and rods

Use Bare and/or insulated conductors

Length of rods is important

Measure ground current Line - Ground fault
from connected bus [14]

Measure ground current Line - Ground fault
from connected line.
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Proceedings of the Sixth International Conference on Trends in Electronics and Informatics (ICOEI 2022)
IEEE Xplore Part Number: CFP22J32-ART; ISBN: 978-1-6654-8328-5
Figure 2.6 - Ground grid 1 summary
Figure2.4 – Grid 1 configuration foroptimized number of
conductors
Figure 2.7 – Ground grid 1 systems with different
simulation
2.2.1 GRID -1 CONFIGURATION AND COST
ANALYSIS
Figure 2.5 – Grid 1 Optimized conductors and rods
Figure 2.8 – Grid 1 configuration and cost analysis
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Proceedings of the Sixth International Conference on Trends in Electronics and Informatics (ICOEI 2022)
IEEE Xplore Part Number: CFP22J32-ART; ISBN: 978-1-6654-8328-5
Normal
Simulation
For
optimized
numbe r of
conductors
Optimized
conductors
and rods
Touch
Potenti
al
Step
Poten
tial
GPR
Grou
nd
Resist
ance
Rg
1.366
Optim
al No.
of
Condu
ctors in
XDirecti
on
-
Optim
al No.
of
Condu
ctors in
YDirecti
on
-
261.5
201.6
2741
295.7
185.8
2786
1.389
3
6
690.5
356.6
3052.5
1.521
3
6
Table 2.1 – Grid 1 configuration analysis
The configuration analysis for Grid 1 is presented in Table
2.1. Various parameters like Touch Potential, Step Potential
etc., are co mpared for normal Simu lation, fo r
optimized number of conductors and for optimized
conductors and rods. The optimized nu mber of earth rods
are 4. Even though the touch potential and step potential
values for optimized conductors and rods are greater when
compared to normal configuration, the values are within the
tolerable values. Also, the overall cost of the earthing grid is
Rs.7,200.
Figure 2.9 – Grid 2 configuration
for normal simulation
2.3 GROUND GRID – 2(IEEE METHOD):
In grid 2, we are using IEEE 80 & 2000/ 2013
method.The shape of the grid is T – shape.Here we are using
four conductors in X direction and four conductors in Y
direction.We are using four number of rods.Here in both
layer we are using mo ist soil which is having 100 oh m – m
resistance.After designing this specification in the grid run
the ground grid study.The results of analysis are showed in
Figure 2.9, 2.10 and 2.11.Ground grid 2 summary with
potential informat ion and fault currents are shown in Figure
2.12. Cost analysis and total number of conductors, rods and
length of conductors, rods are mentioned in figure 2.14.
Figure 2.13 shows the grid 2 information with different
simulation.Based on the soil the resistance is varied and the
GPR is also varied and Rg is also varied.
Figure 2.10 – Grid 2 configuration for
optimized number of conductors
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Proceedings of the Sixth International Conference on Trends in Electronics and Informatics (ICOEI 2022)
IEEE Xplore Part Number: CFP22J32-ART; ISBN: 978-1-6654-8328-5
2.3.1 GRID – 2 CONFIGURATION AND COS T
ANALYSIS
Figure 2.14 – Grid 2 configuration and cost analysis
Touch
Potenti
al
Step
Poten
tial
GPR
Grou
nd
Resist
ance
Rg
1.123
Optim
al No.
of
Condu
ctors in
XDirecti
on
-
Optim
al No.
of
Condu
ctors in
YDire cti
on
-
361.6
243.1
2253.3
564.8
253.7
2425.8
1.209
4
4
656.6
282.5
2472.5
1.232
4
4
Figure 2.11 – Grid 2 Optimized conductors and rods
Normal
Simulation
For
optimized
number of
conductors
Optimized
conductors
and rods
Table 2.2 – Grid 2 configuration analysis
Figure 2.12 – Ground grid 2 summary
The configuration analysis for Grid 2 is shown in in Tab le
2.2. Various parameters like Touch Potential, Step Potential
etc., are co mpared for normal Simu lation, fo r
optimized number of conductors and for optimized
conductors and rods. The optimized nu mbers of earth rods
are 4. Even though the touch potential and step potential
values for optimized conductors and rods are greater when
compared to normal configuration, the values are within the
tolerable values. Also, the overall cost of the earthing grid is
Rs.3,947.
2.3 GROUND GRID – 3(IEEE METHOD):
In grid 3 we are using IEEE 80 & 2000/2013 [15]
method. The shape of the grid is triangular.Here we are using
three conductors in X direction and three conductors in Y
direction.We are using three number of rods.Here in both
layer we are using mo ist soil which is having 100 oh m – m
resistance.
Figure 2.13 – Ground grid 2 systems with different
simulation
After designing this specification in the grid run the
ground grid study.The results of analysis are showed in
Figure 2.15, 2.16 and 2.17.Ground grid 3 summary with
potential informat ion and fault currents are shown in Figure
2.18.Cost analysis and total number of conductors, rods and
length of conductors, rods are mentioned in figure
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Proceedings of the Sixth International Conference on Trends in Electronics and Informatics (ICOEI 2022)
IEEE Xplore Part Number: CFP22J32-ART; ISBN: 978-1-6654-8328-5
2.20.Figure 2.19 shows the grid 3 information with different
simulation.Based on the soil the resistance is varied and the
GPR is also varied and Rg is varied.
Figure 2.17 – Grid 3 Optimized conductors and rods
Figure 2.15 – Grid 3 configurationfor
normal simulation
Figure 2.18 – Ground grid 3 summary
Figure 2.16 – Grid 2 configuration for
optimized number of conductors
Figure 2.19 – Ground grid 3 systems with different
simulation
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Proceedings of the Sixth International Conference on Trends in Electronics and Informatics (ICOEI 2022)
IEEE Xplore Part Number: CFP22J32-ART; ISBN: 978-1-6654-8328-5
2.3.1 GRID – 3 CONFIGURATIONS AND COST
2.3.2ONE LINE DIAGRAM FOR 11KV FEEDER
ANALYSIS
Figure 2.20 – Grid 3 configuration and cost analysis
Touc
h
Poten
tial
Normal
Simulation
For
optimized
numbe r of
conductors
Optimized
conductors
and rods
Step
Poten
tial
GPR
Grou
nd
Resist
ance
Rg
494.8
382.7
2826.7
1.409
Opti
mal
No. of
Cond
uctors
in XDirect
ion
-
Optimal
No.
of
Conducto
rs in YDirection
679.1
386.4
2963.1
1.477
5
5
720.2
339.5
3034.5
1.512
3
3
-
Table 2.3 – Grid 3 configuration analysis
The configuration analysis for Grid 3 is shown in in Tab le
2.3. Various parameters like Touch Potential, Step Potential
etc., are co mpared for normal Simu lation, fo r
optimized number of conductors and for optimized
conductors and rods. The optimized nu mbers of earth rods
are 8. Even though the touch potential and step potential
values for optimized conductors and rods are greater when
compared to normal configuration, the values are within the
tolerable values. Also, the overall cost of the earthing grid is
Rs.3,507.
Figure 2.21 – One line diagram
2.3.3GROUND FAULT CALCULATION
For ground fault calculation two methods are there

User defined

Short circuit study
In user defined ground fault calculation the short circuit
value is given by the user and based on that we have to
calculate the fault calculation.In short circuit study method
we have run short circuit analysis for the grid and the fault
current is updated by the grid itself [16].
3.
CONCLUSION
Since we are using IEEE method the grid shapes are
default only.As per IEEE 80 & 2000/2013 we are having
triangular, rectangle, T – shape and L – shape grids.Main
objective in IEEE method is to obtain minimu m cost while
maintaining safety step and touch potential levels.Main
constraints are to meet step and touch voltage limits.In this
project we are studied about rectangle, triangular and T –
shape grid and the results are showed in pictures.Here main
disadvantage is we cannot design our own shaped grid and
we cannot modify any rods because it is not flexible.To
overcome this disadvantage,FEM method can be used for
flexible grid designs.
REFERENCES
[1] “OPTIMIZATION DESIGN OF GROUND GRID MESH OF 132/33KV
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[2] INST ITUTE OF TECHNOLOGY, NIRMA UNIVERSIT Y,
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Proceedings of the Sixth International Conference on Trends in Electronics and Informatics (ICOEI 2022)
IEEE Xplore Part Number: CFP22J32-ART; ISBN: 978-1-6654-8328-5
[3] “Economic Design of Substation Grounding Grid using ETAP Software:
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