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This guide is for MultiGround package which is made up of 3 engineering modules

RESAP MALT FCDIST

CDEGS is an Integrated Software for Power System Grounding/Earthing, Electromagnetic Fields and Electromagnetic Interference supplied by Safe Engineering Services and technologies ltd.

For more information and deep understanding of the Package go to www.sestech.com

User Guide for Current Distribution, Electromagnetic Fields, Grounding and Soil Structure Analysis (CDEGS) Software Package

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Create file –

Start program

Enter data measured on site

Create multi layer soil model (layer

thickness and resistivities) to be used

in simulations

Enter preliminary (or existing) earthmat grid

(as per earthmat layout drawing)

Enter parameters for simulation- Fault current,

Conductor type

Enter information for connected power lines

(that will share the fault current)

Run simulation to determine GPR, step and touch voltages

CDEGS Design Flowchart

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Start up

Job ID drop down menu appears

NB: All projects for a particular substation must be saved in the same Substation folder for record purposes. Look at the latest job on that particular sub

Create Working Directory

D:User\Data\Substation Name\Project Name

Once complete click OK

Open CDEGS from Start Program or desktop short cut

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Data Entry Simulation Modules Program Output Display

Soil Model

Step/touch/GPR

Fault Current Sharing

CDEGS Main Input Screen

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To enter data, click on Toolbox in the Data Entry window. The following menu will appear

1. RESAP

Module used for Soil Resistivity Analysis from the field measurements

> Click on Toolbox under Data Entry Toolbar > Click on RESAP > Window on Slide number 6 Appears

2. MALT

Module used for Low Frequency Grounding / Earthing Analysis

> Click on Toolbox under Data Entry Toolbar>Click on RESAP > Window on Slide number 10 Appears

3. FCDIST

Module used to determine the sharing in dissipation of the fault current between the substation electrode and the connected power line shield wires > Click on Toolbox under Data Entry Toolbar>Click on FCDIST > Window on Slide number Appears

Modules in CDEGS

We are currently using only the three modules highlighted below:

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Now, click on Measurements to input field data

In TOOLBOX Click on RESAP The following menu will appear

1. Select Job ID

2. Ensure System of Units is Metric

Resap

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Specifying Measurement Conditions:

1. Werner, Long Filter

2. Resistance

3. Ignore Probe Depth

Entering Field Data

• Probe Spacing in meters

• Apparent Resistance values in Ohms

Note: The minimum requirement is 2 sets of soil Resistivity measurements must be taken. Both sets of measurements must be entered

When complete, click on “OK” The program will take you back to Resap

Field Data

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Defining the Soil Model

If Soil Resistivity and Thickness are not known

1. Determine Automatically

2. Horizontal Layers

If Soil Resistivity and Thickness are known

1. User Defined

2. Horizontal Layers

In RESAP window Click on Soil Types. The following menu will appear

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Click OK / Submit to exit the RESAP window and go back to Toolbox

Exiting Resap

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In TOOLBOX Click on MALT. The following window will appear

Now, click on System to CREATE or IMPORT the Grid and Define Grid Energization. See next page

1. Select Job ID

2. Ensure System of Units is Metric

3. Radius in meters

Malt

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CREATE or IMPORT the Grid and Define Grid Energization

2.Put in the coordinates of the grid Conductors and

the Conductor Radius = 0.05m

1. Select Main Ground

3. Select Current (Amps)

4. Enter Fault Current Magnitude

which will be shared at a later stage (FCDIST)Click on Ampacity for Conductor Ampacity Calculation

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Conductor Ampacity Calculation

Enter the following

1. Fault Current in kA

2. Fault Duration in seconds

3. Copper Type (100% not BEE CU)

4. Frequency is 50Hz

Go back to System and click ok to return to MALT

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In MALT window Click on Computation. The following window will appear

Defining the Profile and Surface Aria for which the safety parameters will be calculated

Assuming that on average a human

takes 0.5m (dX or dY) steps when

walking within the substation yard

1. Populate P1

Walking in X direction

N = X / dX (Y and Z are constant)

2. Click on S1and see the next page for

Surface Definition

Computation

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Defining the Profile and Surface Aria

This window appears after clicking on S1

1. Populate the Surface details with Y being

a variable and then click ok

Click OK to return to Computation and OK to return to MALT and then OK /Submit to return to Toolbox

Walking in the Y direction

N = Y / dY (X and Z are constant)

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In TOOLBOX Click on FCDIST. The following window will appear

Ensure that the following is selected

1. Use JobID

2. Metric

3. Meters

4. Both

Click on System and define all the interconnected Return Paths (Shield Wire/OPGW)

Network Fault Current Distribution FCDIST

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Defining the System/Network for FCDIST

3. SectionsSpecifying the total number of structures from the source substation and average span length]Enter the total number of structures 4. Section Length:Enter the average span length5. Tower Impedance: Enter the tower footing Resistance. If value is unknown, an average value of 20 can be used.

1. Average Soil Characteristics Along Electric Lines

Note : This information must be obtained from Network Planning, Network Ops, Plant and Land Development

2. Central Site Name

• Enter the Substation name.e.g. Gull

• Select Use shared data (MALT)

CDEGS will use the data you entered in MALT to calculate the grid resistance

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Define Circuit [ Specifying the height and electricalcharacteristic of the shield wire, as well as the height of the phase conductor where a phase-to-earth fault occurs]

Defining the Circuit

Click on Define Circuit in System window and this window will appear.

Click Import From Database to select the shield Wire from the list(See next page)

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Importing Shield Wire and/or OPGW from Database

1.Click ok to return to Define Circuit window and ok again to return to System window

2.On System window, click NEW if there is more than 1 Terminal go over the process for the new line.

3. When you are done click OK /Submit on System window to return to Toolbox

4.Click Submit All in the Toolbox window to return to CDEGS Main window

(see page 18)

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Data Entry Simulation Modules Program Output Display

Soil Model

Step/touch/GPR

Fault Current Sharing

CDEGS MAIN INPUT SCREEN

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Running Simulation in Engineering window

1. Click on RESAP and then OK once the program has completed Simulation

2. Click on MALT and then OK once the program has completed Simulation

3. Click on FCDIST and then OK once the program has completed Simulation

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RESULTS / OUTPUT

1. Click on Toolbox

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RESAP OUTPUT

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MALT OUTPUT

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OUTPUT

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OUTPUT

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REPORT

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REPORT

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Analyse the results and take corrective measures as per Substation Earthing Standard if any safety requirement is not met

Output