OverCurrent Tutorial

DIgSILENT PowerFactoryApplication Guide

Over-current Protection TutorialDIgSILENT Technical Documentation

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Copyright 2013, DIgSILENT GmbH. Copyright of this document belongs to DIgSILENT GmbH.No part of this document may be reproduced, copied, or transmitted in any form, by any meanselectronic or mechanical, without the prior written permission of DIgSILENT GmbH.

Over-current Protection Tutorial (DIgSILENT Technical Documentation) 1

Contents

Contents

1 Introduction 3

2 Network Modeling 3

3 Using Standard Protection Elements from the Library 3

4 Modeling Protective Elements in Cubicles 8

5 Modeling a New Fuse Type 12

6 Testing the 300 A Fuse 16

7 Modeling the Motor Protection 18

8 Setting the Motor Protection Relay 21

9 Modeling the Transformer Protection 26

10 Modeling the Feeder Cable Protection 26

11 Creating an Overcurrent Path 28

12 Exporting Settings to a Tabular Output 29

13 Performing a Short Circuit Trace 32


3 Using Standard Protection Elements from the Library

1 Introduction

This tutorial demonstrates the modeling and editing of over-current protective devices typicallyfound in distribution and industrial networks. The tutorial has been designed for a user who hasalready used, and is familiar with the basic functions and structure of PowerFactory .

2 Network Modeling

A network model has already been prepared for use. The tutorial comes with five different .pfdfiles, where each one of them represent a specific stage of what is presented in this tutorial asto be done. The first model includes all primary elements, but does not include CTs, VTs orany other protective devices. First of all, import the .pfd project files to PowerFactory , and thenactivate the OC Prot Tut Start project from the DataManager.

Once activated, note that short sections of cables have been modeled between the transformerterminals and those buses that they are connected to. Not only is this a more realistic model, italso presents the opportunity of simulating faults between protective devices of the respectivetransformer HV and LV relays and the transformer itself. Similarly, cables have been added forloads. The user should first perform a load flow of the network to check that all model elementsare defined (this is a normal first order of business step for any newly opened project).


If at all possible, it is recommended that available protective elements from the Global Libraryare utilized, rather than the creation of new relays from scratch. More advanced users shouldthen edit existing types before finally creating new types.

A number of standard protective devices will be used from the library. These devices are:

an ABB SPAJ 140C type relay, used as the Feeder Cable protection relay.

a GE Alstom MCGG63 type relay, used as the Transformer HV protection relay.

a Siemens 7SJ70 type relay, used as the 100 kW Asynchronous Machine protection relay.

a 250 A fuse, used as the LV Load protection.

These relays are available in the Global Library and must be copied over to the project libraryfor use. Though it is not a requirement, it is often useful to keep specific type models together ina library sub folder inside the project library. To do this, such a sub folder must first be created.

Right click on the tutorial project library folder (named Library ). A drop down menu ap-pears.

Select New Folder. The dialog shown below opens. Name the folder Protective De-vices.

Select Library under the Folder Type field.

Click OK. A library sub folder should now appear in the project library.



A destination folder has now been created for the protective devices to be copied to from theGlobal Library. As stated before, these devices could also have been copied directly into theproject library folder. Now the type models in the Global Library must be selected:

Open the Data Manager by left clicking on it.

Move to the top of the database tree.

Left click on the plus sign next to moneLibrary. A list of library folders will drop down.

Open the Relays Library folder. The Data Manager should appear as shown below:

The protective devices required for this study will be found in the Fuses and the Relays subfolders. Start by searching for the correct fuse type model. Opening the Fuses sub folder,by left clicking on the plus sign next to it, opens the dialog shown below. The LV fuses arefound in the VDE0636/IEC60269-2 sub folder. Our intention is to copy the total range of LVfuses into the Project Library folder called Protective Devices, therefore, right click on thisVDE0636/IEC60269-2 fuse sub folder and select Copy.



The Project Library sub folder called Protective Devices must now be selected to paste this setof fuse characteristics into. This is done with a right click on the Protective Devices folder; thenselect Paste.

Now the relay types must be copied to the Project Library. This is done using the same copyand paste operation as used for the fuses, except that relays are now individually selected (asopposed to the whole Relay folder being copied). Starting from the top, first select the SPAJ140 relay as shown below. Note that the path to find this element is, Library RelaysRelaysOvercurrent Relays ABBWestinghouse SPAJ140C. Right click on the SPAJ140Crelay type and select Copy as shown below.



Go to the project library and right click on the Protective Devices folder. Select Paste.Follow the same steps to Copy and Paste over the GE Alstom MCGG63 and Siemens7SJ70 relay types to the Protective Devices folder.

Relay types are modeled using what are known as Relay Frames. The types that we havecopied over from the Global Library are presently still referenced to frames saved in the GlobalLibrary. Similarly, characteristics such as the Current-time curves may be stored outside of therelay type folder. The reason for this is that the frame or the curves may be used by severaldifferent relays in the same family. The type then refers to these common characteristics, in thesame way that an objects element data refers to type data when we draw a network.

Should we export this project, the relay frame references, and the characteristic curve refer-ences, would be lost, because these are not saved in the project itself, only in the Global Library.To correct this, we could copy the frames and characteristics over from the Global Library, andthen we would have to re-select the new addresses of the frames and characteristics into therelay type.

However, this all seems rather complicated for a user only wanting to use standard relay types.To make this process very simple, a special feature called Pack is available. Thus, it is importantthat the following steps be taken whenever relays are copied from the Global Library:

Open the project Protective Devices folder.

Double click the icon of the SPAJ 140C (or right click Edit ; or select Edit Object on theData Manager toolbar) to view the type data of the relay that has been copied. The dialogshown below should open:



Select Pack.

You may be asked Do you really want to copy all used objects into this model? SelectYes.

Press OK on the relay type dialog.

Note that not all relay type will have missing references so not all relays will need to be packed.Once packed you will notice that a plus sign is visible next to the relay type model in the library(if this is there before packing takes place it is not indicative that the relay has been packed).This is because all of the objects that were externally referenced have now been brought intothe relay type itself. Repeat the same steps for the MCGG 63 relay model. Note that the 7SJ70relay comes packed. This is because all the referenced objects for this relay are already savedin the relay type.

You can see if the relay has been packed or not by whether the Pack button is greyed out ornot.


4 Modeling Protective Elements in Cubicles


In the same way that Circuit Breakers and isolator Switches are held/located in a Cubicle, soRelay elements, Current Transformers, Voltage Transformers and Fuses are also located incubicles. These cubicle elements are in turn either located within station models (for busbars),or within Terminals.

To demonstrate this we will start with the modeling of a Load Fuse element:

Right click on the cubicle for the cable feeding the General Load on the 415 V busbarnamed Industrial/B2 (the cable is named Load Cable, as it happens). The cubicle itself isnot a selectable object on the canvas, but the area of the line between the busbar/ terminaland the results box is the defined cubicle area, and right clicking in this area will producethe relevant menu.

This drop down menu now appears, as shown.

Select New Devices Fuse

Note: that if these options do not appear on the drop down menu, the right click was probablynot within the cubicle area. It is sometimes better to first enlarge the view of the cubiclearea in order to perform the right click on the cubicle and not the line or the back-ground.

A fuse element dialog appears.

Name the fuse element Load Fuse.

The fuse type must be defined. Using the selection button at Type, go to Select ProjectType.



In the Protective Devices folder, select the gL-200 A fuse type.

Press OK.

Tick the box Open all 3 Phase Automatically.

Below the option Compute Time Using, select Total Clear Curve.

Press OK.

Note: The Device Number is used for documentation and is an unique identifier for the protec-tion devices stored in the cubicle. To see the fuse characteristic, press the Plot button.

Initially we would want to make sure that the fuse has been properly selected with respect to thenominal load current. For this we need to display the load current in a time-current plot wherethe fusing characteristic of the fuse is also shown. We can use a standard time-overcurrent plotfor this, but first we must calculate the nominal current for the load.

Perform a Balanced Load Flow, ensuring that you have selected all from the list next to ConsiderProtection Devices, on the Advanced Simulation Options submenu.

For the time-overcurrent plot:

Right click on the cubicle containing the newly created fuse.

Select Create Time-Overcurrent Plot.

A new graphic should be created, showing the calculated load current as a vertical line(the default colour of this line is normally red) and the fusing characteristic of the fuse.



Should we decide that the fuse curve appears too close to the load current value we could thenselect a new fuse type from the library, however, this would be time consuming. Instead we caneasily and quickly select an appropriate fuse by following the next few steps:

Double left click anywhere in the plot, but not on the fuse curve or load current value.

The plot editing dialog opens. At the bottom of the plot, under the heading Relay, wenotice the Load Fuse.

Double click in the box Split Relay so that a tick appears in the box.

Press OK.

Note: this action may also be achieved by right clicking on the envelope (that is, the edge)of the fusing characteristic, but accurate mouse positioning is required.

Now left click on the fuse curve, making sure you either click on the melting curve or totalclearing time curve (on the envelope).

It is now possible to change the curve tripping value by holding the cursor down on thecurve and moving it side-ways. Notice how the curve will jump from one position to thenext. The reason for this is that you are effectively selecting different fuses from the library.Since these have discrete fusing characteristics the envelope must jump from one to theother. This method is used later to adjust settings on protective relays as well.

Once the appropriate fusing characteristic is selected double click on the shifted fusecurve to reveal that the Load Fuse element now has a new Fuse type. This new Fuse typehas been selected from within the range of fuses that we copied over to the ProtectiveDevices library earlier; which hopefully makes it clear why we copied the whole libraryover- the fuse can only be chosen from those available in the library folder.

Note that the load vertical line has disappeared when we shifted the fusing characteristic-this is because PowerFactory interprets this as a change to the system, making the calcu-lated results invalid. Say we want to keep the load value as a fixed reference to enable usto better select the fusing characteristic.



Perform a load flow with Consider Protective Devices enabled again (this can be donedirectly from the overcurrent plot by pressing on the Calculate Load Flow button in thetoolbar).

Now right click on the vertical current line. A drop down menu appears.

Select Set User Defined and Yes to the question that follows.

It is now possible to change the fuse value while the load current indication line remains. Alsonotice that if the fuse curve is moved left over the current line the time value at which the twocurves intersect appears automatically.

Notice that the load current indication line and the fusing characteristic are both the same colour.When several overcurrent plots are laid above one another this tool is used to distinguish whichcurrent each device is looking at.


5 Modeling a New Fuse Type


Let us assume that we want to include a unique fuse type to the list of available fuses in ourlibrary. We shall model this fuse by creating a new fuse type. Using the manufacturers fusecatalogue, for the fuse we want to consider, we see that the fusing characteristic curve pointsare as follows:

Operating Current (A) Operating Time795 40955 13

1160 61270 31590 0.92700 0.1

Table 5.1: Fuse Characteristics

The normal PowerFactory fuse model allows for a minimum melt curve and total fault clearingcurve. In this case, however, we only have one set of characteristic curve points. The fuse isthus modelled as follows:

Using a Data Manager, select the fuse library subfolder in the project library. Left click onthis VDE0636/IEC60269-2 subfolder.

The third button from the left on the Data Manager toolbar is the New Object button. Pressthe New Object button. The dialog shown below appears.

Select Special Types and search in the list for Fuse Type (TypFuse) type. Left-click on itand click OK.

Note: The selection for a new fuse type can be found under the Net Element Types set; inolder versions of PowerFactory you will notice a TypFus marked as obsolete. In otherversions the TypFuse is found in the Other object set in the New Object dialogue -the Filter must have Typ* entered to access this (type this in if it is not available asa selection).



A fuse type dialog appears as is shown below. We name this fuse type 300 A Fuse.

The Rated Voltage must be defined as 0.415 kV; the rated current is 300 A; and ofcourse the Rated Frequency is 50 Hz.

A new Melt Curve must be created and defined. Press the down (select) arrow next to MeltCurve and Select Project Type. The program automatically searches the project library fora fuse curve type, and finds the list of curves that were copied earlier. However, we wishto use a new and unique curve. Here we can use the present dialogue to go straight tothe appropriate type target by pressing the New Object button- the program knows whatis required as the Data Manager is focused on the Melt Curves field. A fuse curve typedata sheet now opens.

Alternatively, we can create a new Melt Curve from scratch. A new fuse curve type can becreated by pressing the New Object button and choose an I-t Characteristic (TypChatoc) in theNet Element Types menu. A fuse curve type data sheet now opens. Before pressing this button



make sure that the active folder in the Data Manager is the one that you wish to store the curvein. Normally we will want to store the curve in the same folder as that of the Fuse Type. Oncethe curve has been edited as described below the curve type must be linked to the fuse typeusing the normal selection button for the Melt Curves field in the Fuse Type dialogue.

The fuse curve type object must be named. We will simply call it a 300 A Fuse Curve.Because characteristic curves can be used in both fuses and relays, be sure that theUsage is defined as Fuse.

Open the drop down menu next to Function. By defining the fuse curve in terms of plotvalues, either the Linear Approximation or Hermite Polynomial functions can be used forinterpolation of the fuse curve points. We will use the Hermite Polynomial.

As stated before, a fuse curve would typically consist of two curves defining minimum(Melt) and maximum (Total fault clearing) values. In our case, the fuse curve is only asingle curve, with the values as described in Table 5.1, thus we choose the No. of Curvesto be 1.

Initially only one set of X and Y values is catered for in the dialogue. To create more linesfor X and Y fuse curve values, right click on the first row (on the 1 button) and selectInsert Cells. Various options are available, such as Insert Cells, Append Cells, Append nCells and so forth, which are chosen depending on user requirements.

Fill in the appropriate cell data from Table 5.1.



The fuse curve type data sheet now appears as shown above. By pressing the Plot Curvesbutton, the fuse curve will be shown (please note that the X row values must be always inascending order).

Select OK to return to the Fuse Type dialogue and then OK once more to finish editingthe new fuse type- you will see that the new fuse has now been created in the library.

By moving the fuse plot on the Time-Overcurrent slowly in a horizontal direction across the plotthe new fuse and its characteristic will be selected. If this proves to be difficult (it may since ournew characteristic is markedly different to the others in the library) you can select the fuse typein the normal manner by double clicking on the fuse characteristic envelope. It will be noticedthat the fuse curve become shorter and changes into a single line when the newly created fusetype is selected. Use the new 300 A fuse for the next few steps.

Another way of creating a new fuse type would of course be to copy and paste an existing typein the Data Manager.


6 Testing the 300 A Fuse


To test the newly created fuse, a 3-phase fault is simulated on the terminal to which the LVload is connected (T-Lod). Right click this terminal and select Calculate Short Circuit.

On the Basic Options page of the Short Circuit command, select a fault impedance withResistance, Rf = 0.1 ohm and Impedance, Xf = 0 ohm as is shown below.

Select the Advanced Options page of the Calculate Short Circuit command. Make sure toselect all from the list next to Consider Protection Devices, as is shown below.



Press Execute.

The fuse fault clearing time of 0.179 s is shown on the time-overcurrent plot. If a differentresult has been calculated, repeat the simulation of the short circuit ensuring that it hasbeen correctly simulated.

The complete method should be used for fault calculations as this does not use any approxima-tions and is a far more accurate method of calculating the fault currents. It presents an actualworld picture to the engineer, as opposed to the IEC, VDE and ANSI methods, which havecertain safety margins built in.

Note: This concludes the first stage of the tutorial. Now, please activate the project named OCProt Tut Step 2.

Note: You should notice that the current activated project includes all the changes that weremade before. If you want to make a more detailed comparison, you can do it by means ofusing the DIgSILENT PowerFactory commands Select as Base to Compare and Compareto BaseProject (where the name of the project selected as base will appear instead ofBaseProject). For more detailed information, please refer to the DIgSILENT PowerFac-tory Users Manual.


7 Modeling the Motor Protection


The next element to model is the motor protection relay. As stated before, we will use a Siemens7SJ70 relay for this protection element. The following steps need to be performed:

Right click on the Industrial/B2 415 V busbar cubicle to which the Motor Cable is con-nected. A drop down menu appears.

Select New Devices Relay Model as shown below.

A relay data input dialog appears. Firstly we name this relay Motor Relay.

Click on the arrow down next to Relay Type. Press Select Project Type. The libraryautomatically opens and shows the list of available relays.

Left click on the 7SJ70 relay and click OK. The relay data dialog now appears as shownbelow.



The next logical step is to create a CT element that drives this relay. To do this;

Press Create CT. A CT dialogue box appears.

The only data required is the CT type and if the type is a multi-ratio CT, the selected CTratio. To select the CT type, press the selection arrow, next to Type on the CT elementdialog, and Select Project Type on the drop down menu that appears.

The data manager automatically opens the project library looking for CT types, but findsnone. Press the New Object button in the data manager while making sure the objectis created in the Protective Devices folder (meaning that you must ensure that the folderProtective Devices is the focus of the Data Manager ).

A CT type dialog opens. Name the CT type Multi-Ratio CT Type.

Right click on the first (and only) row inside the Primary Taps dialog. Select Insert Row(s).There will now be two rows of Primary Tap cells. Repeat this two create three rows ofPrimary Tap cells- the Append n Cells could also be used.

Enter the values 75; 150; and 300 A respectively for the Primary Taps. Change theSecondary Tap from 5 A to 1 A. The CT Type dialog should appear as shown below.



Press OK to return to the Select Current Transformer Type dialogue and notice that thenew Multi Ratio CT Type has been created in the library, and that it is highlighted forselection, and press OK again to return to the Current Transformer Element dialogue.

In this CT element dialogue box, select the ratio to be 150/1 as shown next.

Press OK.

Press OK on the relay element dialogue and OK again on the cubicle dialogue.

The motor protection has now been completely modeled, but not set.


8 Setting the Motor Protection Relay


First a load flow is performed, considering all Protective Devices. Now the following steps arefollowed:

Left click on the Edit Relevant Objects for Calculation button (this also known as the objectfilter button), which is the second tool on the toolbar. A small screen appears with differentelement (green) and type (red) symbols.

Left click on the green Relay Model (*.ElmRelay ) symbol. A list of all used relays willappear. Note that there is only one relay in our current list.

Double left click on the relay symbol next to Motor Relay. Note that you can also get tothis point by right clicking on the cubicle where the relay is and then select Edit Devices.

The relay editor appears again. Double click on the field to the right of the (look underThe Relay Model in the help index for more information on how relays are modelled) I>symbol (in the net elements column) and set the relay Pickup Current to 3.9 p.u. andTime Setting to 5.0 seconds.

The convention used for the overcurrent symbols is fairly widespread and is explained below forclarity of purpose:

The > symbol is used to indicate the designed chronological sequence of the tripping charac-teristics used by the relay, so that increased use of the > symbol may mean, for example:

I> overcurrent with inverse tripping characteristic (slowest actingtripping element)I>> instantaneous tripping with a time delay (mid term tripping element)I>>> instantaneous tripping without a time delay (fastest acting trippingelement)

Where a relay has only a moderate inverse characteristic and an instantaneous characteristicthe >>indicates the instantaneous characteristic since this is of course the fastest character-istic that the relay has.

Press OK.

Double click on the I>> field and set the Pickup Current to 15 p.u. Press OK.



Lastly double click on the IE> symbol and set the earth fault Pickup Current to 0.5 p.u.Press OK to return to the relay dialogue box and OK again on the relay editor/ dialoguebox to return to the Object Filter. Close the Object Filter.

Perform a load flow with the consideration of all Protective Devices.

Right click on the cubicle containing the newly created motor protection.

Select Add to Time-Overcurrent Plot.

The time-overcurrent plot should appear as shown next.

The red current value and red curve represent the current and characteristic fuse curve forthe LV load. The green current and green curve represent the current and curve/s of the newlycreated motor protection. To be able to see a larger current range on the time-overcurrent curve,the following steps are taken.

Double click anywhere on the plot, but making sure it is not on either protection curve orcurrent values.

The time-overcurrent curve editor opens as shown below.



Change the Maximum Limit value on the x-Scale to 100,000.

Press OK.

A larger section of the green curve is visible.

You can also instruct the program to automatically scale the axes by pressing the Scalex-Axes automatically, or, Scale y-Axes automatically, buttons.

Next we want to make sure that the motor protection relay will not trip under motor startingconditions.

Go to the network view and right click on the motor.

On the drop down menu, select Show Add to Time-Overcurrent Plot.



A blue motor starting curve appears on the time-overcurrent plot. We can see that the protectionsetting is higher than the motor starting plot. However, we may wish to increase the time settingfor the I> part of the curve.

Double click anywhere on the plot, but not on any curve or current value.

The plot editor opens.

Click in the Split Relay box next to Motor Relay and press OK. This may also be achievedby right clicking the relay time characteristic line and selecting Split.

Left click on the horizontal part of the I> curve (hover the cursor over the line to determinewhich one is the I> curve if you are unsure). Note that the relay curve can be moved byholding down the cursor on it and dragging the curve up and down. Drag the curve to themaximum time setting available- this maximum time is determined by the relay type thatwe have selected.

Double click on the plot again (or right click on the I-t characteristic line) and unsplit theMotor Relay. Press OK.

Now we want to make sure that the protection is sensitive enough to operate for overcurrentconditions. To do this:

Right click on the terminal to which the motor is connected.

Select Calculate Short Circuit as shown below.



A three phase short circuit is modeled with the same values that were selected before when the300 A fuse was tested. Set the fault resistance to Rf = 0 ohm.

Press Execute and look at the time-overcurrent plot.

We have set the relay to be sensitive to maximum fault conditions, whilst being stable undermotor starting and load flow conditions.

Note: This concludes the second stage of the tutorial. Now, please activate the project namedOC Prot Tut Step 3.


10 Modeling the Feeder Cable Protection

9 Modeling the Transformer Protection

For this project, we model only the transformer HV protection, using a MCGG63 type relay. Thesteps should by now be familiar, but are briefly repeated.

Right click on the cubicle feeding the HV side of the transformer from the Industrial/B1substation busbar.

Select New Devices Relay Model. Name the new relay element Transformer Relay.

Select the MCGG63 relay type from the project library.

Press Create CT and name the CT Transformer CT.

Select the Multi-Ratio CT type from the project library.

Choose the CT ratio to be 75/1.

Press OK.

Double click on the Toc Ph element and set it to a Current Setting value of 2.2 p.u. andTime Dial of 0.8. Press OK.

Double click the Ioc Ph element and set the Pickup Current to 7 p.u. and the TimeSetting to 0.095 s. Press OK.

Press OK on the relay editor and OK on the cubicle editor.


As stated before, the Feeder Cable protection that we will use is an ABB SPAJ140C type relay.This is modeled as follows:

Right click on the cubicle feeding the Feeder Cable from the Intake/Incomer substationbusbar.

Select New Devices Relay Model. Name the new relay element Feeder Relay.

Select the SPAJ140C relay type from the project library.

Press Create CT and name the CT Transformer CT.

Select the Multi-Ratio CT type from the project library.

Select the CT ratio to 300/1.

Press OK.

Double click on the I> element and set it to a Current Setting value of 1 p.u. and TimeDial of 1. Press OK.

Double click the I>> element and set the Pickup Current to 5.3 p.u. and the Time Settingto 0.36 s. Press OK.



Double click the Io> element and set the Current Setting to 0.2 p.u. and the Time Dialto 0.3. Press OK.

Double click the Io>> element and set the Pickup Current to 0.4 p.u. and the TimeSetting to 0.4 s. Press OK.

Press OK on the relay editor and OK on the cubicle editor.


11 Creating an Overcurrent Path

11 Creating an Overcurrent Path

It is useful to create paths for ease of creating and editing overcurrent relay settings. To dothis, multi-select all busbars, lines/cables, terminals etc. in the desired path and right click themulti-selection as shown below.

Select Path New. In the path dialog, name the path Red Path. Click OK.

We can now right click anywhere on the path and select Path Create Time-OvercurrentPlot (the path must first be de-selected by clicking anywhere outside of the path).

A new time-overcurrent plot appears. We can again reset relays by first splitting relay curvesand then by dragging the curves. If we would like to confirm that the transformer is adequatelyprotected from thermal damage due to overcurrents, follow the next steps:

Right click on the transformer.

Select Show Add to Time-Overcurrent Plot. A window appears listing the two curves created so far. We can now select on which plot

the transformer damage curve should be added.

Select the second plot- Time-Overcurrent Plot(1), and press OK.

We note that the transformer damage curve is only just above the transformer protectionrelay curve.


12 Exporting Settings to a Tabular Output


PowerFactory v15 introduces a completely new tabular reporting format which vastly improvesthe protective device setting reporting capability of the software. With the previous approachASCII reports for protection settings were generated in the output window which were not ableto deal with the structure of complex relay models. Furthermore the settings could not easily beexported to other software environments like Microsoft Word or Excel. The new tabular reportcommand (ComTablereport) overcomes these problems by generating pre-configured tabularoutputs customized to the protective device class.

A report command specifically for protection can be accessed by either clicking on the Output ofProtection Settings icon on the Protection toolbar or alternatively selecting from the main menuOutput Protection Output of Protection Settings, as is shown below.

A dialog will appear, showing the options to generate several reports. By default, PowerFactorycomes with the selection of the Instrument Transformers and Overcurrent Protection reports.For each option selected, PowerFactory will generate a dialog, including all the chosen data.For now, please leave only the Overcurrent Protection box ticked.

In the field of Protective Devices are two options presented: you could rather choose to have atabular report of all the protection devices or to make a selection of them. To do this:

Left click on the Edit Relevant Objects for Calculation icon, and select the green RelayModel (*.ElmRelay ) symbol. A list of all used relays will appear. Note that there should be3 relays on the list.

Select the Transformer Relay and the Feeder Relay, holding the CTRL button whiledoing right click on the corresponding green icons.

Left click on any part of the selection and choose Define General Set. A dialog appears. Right click on Close button and close the Object Filter dialog.

Return to the Output of Protection Settings dialog, as stated before.



Select User Selection in the Protection Device field.

Select the down arrow button next to Selection and right click on Select.

On the dialog, go to Study Cases Study Case and make sure to select the item GeneralSet on the right pane. Press OK.

Now go to the Common Options submenu. Here you can specify the number of decimal digitsyou want to have in the tabular output, as well as the Layout Options for the report. The threeselected columns in the Layout Options field will appear at first of the tabular output dialogue.You can rearrange the order of the columns by means of using the >> and


You can also access to the main dialog of the relay element through the tabular output. Leftclick on the cell Transformer Relay. As you can see, a new dialog is shown but is the samedialog from which you can access to the relay settings.


13 Performing a Short Circuit Trace


Sometimes is desired to have a quick look over the performance of the protection scheme, takinginto account the dynamic behavior of relay tripping under shortcircuit conditions. PowerFactoryintroduces a new tool named Short Circuit Trace based on the calculation of the fault currentsthrough the complete method, for a single or a group of faults, to determine the relays trippingtime due to the measured current that flows through the associated branches.

Note: Please activate the project named OC Prot Tut Step 3

Now, as you can see below, there has been a slight change on the topology of our test sys-tem. We have added a new Feeder Cable with its corresponding relay, which has the samesettings as the relay created before (Feeder Relay). Our goal is to simulate a fault near theIntake/Incomer busbar, in order to observe what happens with the behavior of the protectionscheme.

To perform the Short Circuit Trace, please do the following:

Left click on the center of the Feeder Cable. A menu appears. Select Calculate ShortCircuit Trace.

A new dialog is shown. Right click on the Short-Circuit Event cell and select Edit.

You will notice that the Feeder Cable is already selected as the element to be faulted.Left click on the arrow button right next to the Feeder Cable element.



Go to the Complete Short-Circuit submenu and enter 5 in the Short-Circuit Locationfield. Press OK.

Now the Fault Location is defined to be at 5% from the Intake/Incomer busbar. PressOK.

Press Close.

The Short Circuit Trace dialog appears. Left click on the arrow next to Command. Go tothe Advanced Options submenu and select Mixed Mode from the Calculate relay trippingwith field. Define the Sub-Transient Time to be as 0,5 s.

Press Close.

Now, we have all prepared for the Short Circuit Trace calculation. Press Execute. Thefirst stage of the fault calculation is shown as next.



As you would notice, the simulated 3-Phase fault is not only being fed through the Feeder Cable,but also from the New Feeder Cable as well. For the Next Time Step, please left click on theblack left arrow, in the Protection toolbar.

Now the Feeder Cable relay has tripped at 0,36 s, as you will notice a red circle surrounding thecubicle area. Nonetheless, the fault is still being fed, but now all the current is going through theNew Feeder Cable. At this point, PowerFactory has recalculated the 3-Phase fault, using theinitial conditions which are the same as the final values at the end of the first stage, but with anew topology condition, thus showing the new current distribution.



For the last step, observe that the relay associated to the New Feeder Cable has now tripped.




IntroductionNetwork ModelingUsing Standard Protection Elements from the LibraryModeling Protective Elements in CubiclesModeling a New Fuse TypeTesting the 300 A FuseModeling the Motor ProtectionSetting the Motor Protection RelayModeling the Transformer ProtectionModeling the Feeder Cable ProtectionCreating an Overcurrent PathExporting Settings to a Tabular OutputPerforming a Short Circuit Trace

OverCurrent Tutorial

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Transcript of OverCurrent Tutorial