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Figure 1: Substation Layout

structure connection operating handle

10m

Third Party Equipment

Strategy & Solutions Limited

Figure 2a: Soil resistivity data.

10 -1 10 0 10 1 10 2

Average Inter-Electrode Spacing (metres)

10 1

10 2

10 3

ApparentResistivity(Ohm-metres)

METRIC/LOGARITHMIC X AND Y

Strategy & Solutions Limited

Figure 2b: 3 layer, 2 layer and uniform soil resistivity curve.

10 -1 10 0 10 1 10 2

Average Inter-Electrode Spacing (metres)

10 1

10 2

10 3

Apparent Resistivity (Ohm-metres)

METRIC/LOGARITHMIC X AND Y

2 Layer Equivalent

Uniform Equivalent

Strategy & Solutions Limited

Figure 3: First draft electrode system.

Earth electrode 0.6m deep

3.6m earth rods

Fence earth rods

Strategy & Solutions Limited

-17.5 -10.5 -3.5 3.5 10.5 17.5

X AXIS (METERS)

-14

-7

0

7

14

21

Y A

XIS

(M

ET

ER

S)

Top View of Conductors

ALL ELECTRODES/NO LABELING [ID:Basic_Model_3.6M]

Figure 4: Basic computer model.

Strategy & Solutions Limited

-17.5 -10.5 -3.5 3.5 10.5 17.5

X AXIS (METERS)

-14

-7

0

7

14

21

Y A

XIS

(M

ET

ER

S)

Top View of Conductors

ALL ELECTRODES/NO LABELING [ID:Detail_Model]

Figure 5: Detailed computer model.

Figure 6: Touch voltage above earth grid.

-15 -5 5 15

X AXIS (METERS)

-15

-5

5

15

25

Y A

XIS

(M

ET

ER

S)

1 1

11

11

11

1

2

22

22

2

2

3

3 3

33

3

4

4 44

4

5

55 5

5

5

5

5

6

66

66

6

6

7

7

7

7

7

7

8

8

8

8

9

9

9

9

10

10

10

11

11

11

12

12

12

12

1313

13

14

14

14

15

15

16

16

17

17

18

18

1920

Touch Voltage Magnitude (Volts)

SINGLE-ELECTRODE/TOUCH VOLTAGES/USER DEFINED [ID:Detail_Model] LEGEND

MAXIMUM VALUE : 765.9462

MINIMUM VALUE : 44.12939

Level 20 ( 240.000 )

Level 19 ( 210.000 )

Level 18 ( 197.000 )

Level 17 ( 190.000 )

Level 16 ( 180.000 )

Level 15 ( 160.000 )

Level 14 ( 145.000 )

Level 13 ( 140.000 )

Level 12 ( 135.000 )

Level 11 ( 130.000 )

Level 10 ( 120.000 )

Level 9 ( 115.000 )

Level 8 ( 110.000 )

Level 7 ( 100.000 )

Level 6 ( 95.0000 )

Level 5 ( 90.0000 )

Level 4 ( 80.0000 )

Level 3 ( 70.0000 )

Level 2 ( 60.0000 )

Level 1 ( 50.0000 )

Figure 7: Surface potentials across earth grid.

-30 -15 0 15 30

X AXIS (METERS)

-30

-15

0

15

30

Y A

XIS

(M

ET

ER

S)

1

2

3

4

Potential Profile (% reference GPR)

MULTIPLE-ELECTRODE/SCALAR POTENTIALS [ID:Detail_Model] LEGEND

MAXIMUM VALUE : 95.18864

MINIMUM VALUE : 19.55564

Level 4 ( 85.2000 )

Level 3 ( 62.9000 )

Level 2 ( 50.0000 )

Level 1 ( 36.6000 ) 33kV Fault

11kV Fault

Figure 8: Surface potentials across final earth grid installation.

-30 -15 0 15 30

X AXIS (METERS)

-30

-15

0

15

30

Y A

XIS

(M

ET

ER

S)

1

2

3

4

4

Potential Profile (% reference GPR)

MULTIPLE-ELECTRODE/SCALAR POTENTIALS [ID:Detail_Model] LEGEND

MAXIMUM VALUE : 96.47353

MINIMUM VALUE : 24.88441

Level 4 ( 91.1000 )

Level 3 ( 75.0000 )

Level 2 ( 65.0000 )

Level 1 ( 53.0000 ) 33kV Fault

11kV Fault

Figure 9: Touch voltage above final earth grid installation.

-15 -5 5 15

X AXIS (METERS)

-15

-5

5

15

25Y

AX

IS (

ME

TE

RS)

1

1

1

11

11

2

22

2

2

2

3

33

3

3

3

3

4

4

4

5

5

5

6

6

66

789

Touch Voltage Magnitude (Volts)

SINGLE-ELECTRODE/TOUCH VOLTAGES/USER DEFINED [ID:Detail_Model_final] LEGEND

MAXIMUM VALUE : 456.8643

MINIMUM VALUE : 23.53455

Level 9 ( 110.000 )

Level 8 ( 100.000 )

Level 7 ( 90.0000 )

Level 6 ( 80.0000 )

Level 5 ( 70.0000 )

Level 4 ( 60.0000 )

Level 3 ( 50.0000 )

Level 2 ( 40.0000 )

Level 1 ( 30.0000 )

Figure 10: Step voltage above final earth grid installation.

Figure 11: Leakage current along vertical rod.

-16.5 -13.5 -10.5 -7.5 -4.5 -1.5

X AXIS (METERS)

13.5

10.5

7.5

4.5

1.5

-1.5Z

AX

IS (

ME

TE

RS)

5.7

1.4

0.91

4.5

1.0

1.1

1.2

1.3

1.3

1.4

1.5

1.5

4.5

4.6

4.7

4.7

4.8

4.9

5.0

5.0

5.2

5.3

5.5

5.8

6.7

465

Side View of Leakage Currents (Amps)

ALL ELECTRODES/LEAKAGE CURRENTS (SINGLE & MULTIPLE) [ID:Detail_Model]

Soil Surface

59Ωm, 1.1m

104Ωm, 4.6m

35Ωm, infinite.

1.4A

11.21A

71.2A

Figure 12: Surface potentials above final installation, in 3D.