Ch16 Star Devcoord

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Chapter 16

Star Device Coordination Analysis

Star is a fully integrated system protective device coordination/selectivity module within ETAP. Starrepresents a new concept in performing steady-state and dynamic device coordination, protection, andtesting. This is achieved by utilizing intelligent one-line diagrams, comprehensive device libraries, and anintegrated three-dimensional database.

Star enables system engineers to easily and efficiently perform protective device coordination studies.The built-in intelligent features provide informed and reliable recommendations regarding the feasibilityof the devices under consideration. This helps system engineers and planners quickly realize possibledesign issues and make informed decisions to improve system reliability, increase system stability, and

boost financial savings.

This Chapter provides an overview of some of the features of Star. By reading this Chapter, you will become familiar with many of the key concepts and capabilities of the module. Each section is availablein an interactive format, allowing you to visualize each step as it is explained in this chapter.

Note: Some of the directory paths shown in the figure below will be different if you have chosen a custominstallation path.

Operation Technology, Inc. 16-1 ETAP 5.0 User Guide


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Star Device Coordination Star Mode Toolbar

16.1 Star Mode Toolbar

Create Star View

Run / Update Short-Circuit Clipping kA

Fault Insertion (PD Sequence-of-Operation)

Display Options

Report Manager

Device Settings Reports

Halt Current Calculation

Sequence Viewer

Create Star ViewClick this button to generate a new Star presentation. A Star View is a presentation that may containnetwork paths (a set of one or many elements that reside in the one-line diagram) and their specific plots.To activate the Create Star View toolbar button, select an element or a group of elements on the one-linediagram. This is called rubber-banding a zone for a selected Configuration. Composites can be opened up,rubber-banded, and grouped with their external connecting elements for coordination.

Run / Update Short-Circuit Clipping kAClick this button to perform a short-circuit study that updates the time-characteristics curve clipping kAfor the applicable elements. This study will calculate momentary (½ cycle) symmetrical and asymmetricalrms 3-phase, as well as line-to-ground fault values per the options selected in the active Star mode studycase. If the output file name is set to prompt, ETAP will prompt you to specify the output report name.The study results will then appear on the one-line diagram and in the output report.

Fault Insertion (PD Sequence-of-Operation)PD operation sequence calculation will initiate upon placing a fault on the one-line diagram using theFault Insertion button from the Star mode. the fault insertion icon changes based on the fault type

selection (phase or ground).

Phase Ground

Once fault insertion button is depress the cursor icon changes to a fault symbol which can be dropped onvalid AC one-line diagram elements i.e. buses, connectors. As you move Fault Insertion cursor over theone-line diagram, the cursor color changes to Red indicating an allowable (valid) fault insertion location.



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The fault insertion cursor can be dragged and re-dropped on any valid one-line diagram to initiate a newsequence-of-operation calculation. To cancel the fault insertion, press the Esc button .

Fault Insertion is not allowed for the following:• De-energized elements• Panel systems• DC elements• Grounding elements• CT / Relay connections• Composite Motor elements

Display OptionsSee the Display Options Section in this Chapter for more information about customizing displayannotations on the one-line diagram. The Display Options – Star (PD Coordination) dialog box containsoptions for Star short-circuit study and sequence-of-operation results, as well as associated device

parameters.

Report ManagerShort-circuit output reports are provided in Crystal Reports format. The Star Report Manager containsfour pages (Complete, Input, Result, and Summary) for viewing the different parts of the output report inCrystal Reports. (ETAP displays either the ANSI or IEC version of the dialog box, depending on thestandard selected for the current study case.)

Available formats for Crystal Reports are displayed on each page of the Report Manager for short-circuitclipping ka and sequence-of-operation studies. You can open the whole output report or only a part of it,depending on your format selection.



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You can also view output reports by clicking the List Output Reports button on the Study Case Toolbar.

List Output Reports Button

A list of all output files in the selected project directory is provided for the performed calculations. Toview any of the listed output reports, click the output report name, and then click the View Output Report

button.

The output reports for Star short-circuit studies have an extension of .ST1 and .ST2 for ANSI and IECstandards, respectively.

The output reports for Star sequence-of-operation studies have an extension of .SQ1 and .SQ2 for ANSIand IEC standards, respectively.

Device Settings ReportsClick the Device Settings Reports button to display the Device Coordination Reports Manager. Themanager allows you to preview and print the protective device setting data, as entered in the overcurrent



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relay, overload relay, MV solid-state relay, fuse, low voltage circuit breaker, and overload heater usingthe Crystal Reports formats.

To print the device settings:1. Click the Device Settings Reports button. The Device Coordination Report Manager editor displays.2. Select the desired report type for the all or selected element on the one-line diagram.3. Select the Base or Revision data, and then click OK.

When you select a report, ETAP will ask if you would like to save the project prior to generating thereport.

Clicking the Ok button will save the latest changes to the database and launch the selected report. ClickCancel to exit back to the previous editor. Note that the project database can only be saved in Baserevision.

The report displays device settings for the selected devices or all devices on the one-line diagramincluding De-energized and Dumpster elements.



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Star Device Coordination Study Case Editor

16.2 Study Case EditorThe Star Mode Study Case editor contains solution control variables, faulted bus selection, and a varietyof options for output reports. ETAP allows you to create and save an unlimited number of study cases.Star short-circuit and sequence-of-operation calculations are conducted and reported using the settings ofthe study case selected in the toolbar. This allows you to switch between study cases without having toreset the study case options each time. This feature is designed to organize your study efforts and saveyou time.

With respect to the multi-dimensional database concept of ETAP, study cases can be used for anycombination of the three major system components. The system components are configuration status,one-line diagram presentation, and Base and Revision Data.

You can access the Star Mode Study Case editor by clicking the Edit Study Case button on the StudyCase toolbar. You can also access this editor from the Project View by double-clicking the study casename in the Star Analysis folder.

To create a new study case, go to Project View, right-click the Star Analysis Study Case folder, and selectCreate New. The program will then create a new study case, which is a copy of the default study case, andadd it to the Star Analysis Study Case folder.



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16.2.1 Info Page

Study Case IDThe Study Case ID is displayed in this text box. You can rename the study case by deleting the old ID andentering a new one. The study case ID can be up to 12 alphanumeric characters. Use the Navigator

buttons at the bottom of the editor to display any of the exiting study cases in the editor.

Transformer TapThe following two methods are provided for modeling transformer off-nominal tap settings:

Adjust Base kVBase voltages of the buses are calculated using transformer turn ratios, which include the transformerrated kVs as well as the off-nominal, tap settings.

Use Nominal TapTransformer rated kVs are used as the transformer turn ratios for calculating the base voltages of the buses (that is, all off-nominal tap settings are ignored and transformer impedances are not adjusted).

If a system contains transformers with incompatible voltage ratios (including taps) in a loop, it can lead totwo different base voltage values at a bus, which prevents the short-circuit calculation from continuing. Ifthis situation occurs, ETAP will post a message to inform you and give you the option to continue thecalculation with the Use Nominal Tap option. If you click Yes, it will carry out the calculation with theUse Nominal Tap option.



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Cable/OL HeaterSelect the appropriate check boxes in this group to include the impedance of equipment cable andoverload heaters of medium (MV Motor) and/or low voltage (LV Motor) motors in short-circuit studies.

Motor Contribution Based onSelect one of the following options for considering motor contribution in short-circuit studies:

Motor StatusWhen this option is selected, motors whose status is either Continuous or Intermittent will makecontributions in short-circuit. Motors with Spare status will not be considered in the short-circuit analysis.

Loading CategoryWhen this option is selected, you can select a loading category from the selection box to the right. In theshort-circuit calculation, motors that have non-zero loading in the selected loading category will have acontribution in short-circuit. Motors with zero loading in the selected loading category will not beincluded in the short-circuit analysis.

BothWhen this option is selected, a motor will make a contribution in the short-circuit analysis if it meetseither the Motor Status or the Loading Category condition. That is, for a motor to be excluded from theshort-circuit analysis, it would have to be in the Spare status and have zero loading in the selected loadingcategory.

Bus SelectionETAP is capable of faulting one or more buses in the same run; however, multiple buses are faultedindividually, not simultaneously. Depending on the specified fault type, the program will place a 3-phase,line-to-ground, line-to-line, and line-to-line-to-ground fault at each bus that is faulted for short-circuitstudies.

When you open the Star Mode Study Case editor for the first time, all buses are listed in the Don’t Faultlist box. This means that none of the buses are faulted. Using the following procedures, you can decidewhich buses you want to fault for this study case.

• To fault a bus, highlight the bus ID in the Don’t Fault list box and click the Fault button. Thehighlighted bus will be transferred to the Fault list box.

• To remove a bus from the Fault list box, highlight the bus ID and click the ∼ Fault button. Thehighlighted bus will be transferred to the Don’t Fault list box.

• If you wish to fault all buses, medium voltage buses, or low voltage buses, select the appropriateoptions and click the Fault button. The specified buses will be transferred from the Don’t Fault list

box to the Fault list box.•

To remove all buses, medium voltage buses, or low voltage buses from the Fault list box, select theappropriate options and click the Fault button. The specified buses will be transferred from the Faultlist box to the Don’t Fault list box.

Study RemarksYou can enter up to 120 alphanumeric characters in this field. Information entered here will be printed onthe second line of every output report page header line. These remarks can be used to provide specificinformation about each study case.



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Note: The first line of the header information must be the same for all study cases. To change the firstline, from the Project menu, select Information and change the Remarks text box.

16.2.2 Standard Page

StandardBoth ANSI and IEC standards are available for short-circuit studies. Select the short-circuit studystandard by clicking the standard notation. Different sets of solution control variables (prefault voltage,calculation methods, etc.) are available for each standard.

When you create a new study case, the short-circuit standard is set equal to the project standard you havespecified in the Project Standards dialog box (from the Project menu, select Standards). You can changethe study case standard independently of the project standard.

When the ANSI standard is selected, this page will appear as shown below.

When the IEC standard is selected, the study options will change and you will see the page shown below.



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Prefault Voltage - ANSI StandardYou can select either fixed or variable prefault voltages for all buses.

FixedThis option allows you to specify a fixed prefault voltage for all the faulted buses. This fixed value can bein percent of bus nominal kV or base kV. Bus nominal kV is the value you entered in the Bus Editor torepresent the normal operating voltage. The bus base kV is calculated by the program and is only reportedin the results section of the Star Mode short-circuit report for each faulted bus.

The process of computing base kV starts from one of the swing machines, such as a utility or a generator, by taking its design voltage as the base kV for its terminal bus. It then propagates throughout the entiresystem. When it encounters a transformer from one side, the transformer rated voltage ratio will be usedto calculate the base kV for the buses on other sides. If the Adjust Base kV option is selected on the InfoPage of the Star Mode Study Case editor, the transformer tap values will also be used in the base kVcalculation along with transformer rated voltage ratio. This calculation procedure demonstrates that the

base kV is close to the operating voltage, provided that the swing machine is operating at its design

setting.

Vmag X Nominal kV (from Bus Editor)If you select the Vmag X Nominal kV (from Bus Editor) prefault voltage option, ETAP uses the busvoltages entered in the Bus editors as the prefault voltage for faulted buses. Using this option, you can

perform short-circuit studies with each faulted bus having a different prefault voltage. For instance, youcan perform short-circuit studies using the bus voltages calculated from a specific load flow study and,therefore, calculate fault currents for an actual operating condition. To do so, from the Info page of the



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Load Flow Study Case editor, select Initial Bus Voltages from the Update group. Then, run a load flowanalysis.

Since the short-circuit current is proportional to the prefault voltage, different options will most likelygive different results. However, with any of the above options, the calculated fault current is the same aslong as the prefault voltage in kV is the same. The options used for a study depend on your judgment andthe objective of the study. If you want to calculate the fault current to size protective switching devices,you may want to apply the maximum possible prefault voltages in the calculation. This can be done byselecting the Fixed option with Base kV. If the bus normal operating voltage is entered in the Bus Editoras the bus nominal voltage, you may also use the Fixed option with Nominal kV.

Prefault Voltage - IEC StandardEnter voltage C factors for the indicated bus voltage levels. The equivalent voltage source used in the IECshort-circuit calculations will be adjusted according to the voltage factors you enter in this study case.

The defaults of the voltage C factors are from Table I of the IEC 909 Standard.

230 V & 400 V C Factor = 1.0Others < 1001 V C Factor = 1.051001 to 35000 V C Factor = 1.1> 35000 V C Factor = 1.1

In calculations of the minimum steady-state short-circuit current, the factor Cmin is used as specified inIEC 909 Standard.

Zero Sequence Z

Include Branch Y & Static LoadThis option allows you to consider the effect of zero-sequence capacitances of lines and cables, as well as

shunt admittances of distinct static load elements for IEC 909 LG short-circuit calculations. This meansthat if a cable has a susceptance value specified under the Y field (impedance page), ETAP will convertthis value into the zero sequence capacitance and consider it in the calculation of 3Io.



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16.2.3 Seq of Op. PageThis page provides the parameters for performing protective device sequence-of-operation analyses.

Fault ValueSelect Asymmetrical or Symmetrical value to be considered for phase or ground fault type.

Protective Devices ConsideredChoose the maximum bus level away from the fault which the study will check for protective deviceoperation.

Fault TypeSelect from 3 Phase, Line-to-Ground, Line-to-Line, or Line-to-Line-to-Ground fault type for protectivedevice sequence-of-operation study. This will change the Fault Insertion (PD Sequence-of-Operation)

button accordingly.



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16.2.4 Adjustment Page

Impedance ToleranceThis group allows the user to consider tolerance adjustments to equipment resistance and impedance.Each tolerance adjustment can be applied based on the individual equipment percent tolerance setting or

based on a globally specified percent value.

TransformerThis adjustment is applied to the transformer impedance. The adjustment includes positive, negative, andzero sequence impedance depending on the type of fault being performed (3-Phase or LG, LLG, and LL).The net effect of the transformer impedance adjustment in short-circuit calculations is to decrease theimpedance by the specified percent tolerance value. For example, if the transformer impedance is 12%and the tolerance is 10%, the adjusted impedance used in the short-circuit calculation will be 10.8%,resulting in a higher fault current.

The impedance adjustment can be applied to individual transformers by using the tolerance percent valuespecified on the Rating page of the Transformer Editor. A global transformer impedance adjustment can

be specified as well by selecting and specifying a global tolerance other than 0% in the correspondingfield on the Adjustment page of the Star Mode Study Case editor. The global impedance adjustmentoverrides any individual transformer tolerance value.

ReactorThis adjustment is applied to the reactor impedance. The Star Mode Short-Circuit reduces the reactorimpedance by the specified percent tolerance resulting in smaller impedance and consequently a higher



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fault current. For example, if the impedance of the reactor is 0.1 Ohm and its tolerance is 5%, then theadjusted reactor resistance used in the short-circuit calculation is 0.095 Ohm.

The impedance adjustment can be applied to individual reactors by using the tolerance percent valuespecified on the Rating page of the Reactor Editor. A global reactor impedance adjustment can bespecified as well by selecting and specifying a global tolerance other than 0% in the corresponding fieldon the Adjustment page of the STAR Mode Study Case editor. The global impedance adjustmentoverrides any individual reactor tolerance value.

Overload HeaterThis adjustment is applied to the overload heater (OH) resistance. The Star Mode Short-Circuit reducesthe OH resistance by the specified percent tolerance resulting in smaller resistance and consequently ahigher fault current. For example, if the resistance of the OH is 0.1 Ohm and its tolerance is 5%, then theadjusted OH resistance used in the short-circuit calculation is 0.095 Ohm.

The resistance adjustment can be applied to individual overload heaters by using the tolerance percentvalue specified on the Rating page of the Overload Heater Editor. A global overload heater resistanceadjustment can be specified as well by selecting and specifying a global tolerance other than 0% in thecorresponding field on the Adjustment page of the Star Mode Study Case editor. The global resistanceadjustment overrides any individual overload heater tolerance value.

The adjustments only apply if the Cable/OL Heater option is selected for MV or LV motors.

Synchronous Machine Direct-Axis Subtransient Reactance (X” d) AdjustmentThe direct-axis subtransient reactance (X” d) for a synchronous generator or a synchronous motor willalways be adjusted by the X” d tolerance value entered in the Imp/Model page of the corresponding editor.The Star Mode Short-Circuit reduces the X” d value by the specified percent tolerance resulting in smallerimpedance and consequently a higher fault current. For example, if the X” d value is 10% and its toleranceis 5%, then the adjusted X” d value used in the short-circuit calculation is 9.5%.

Impedance Tolerance for IEC Minimum Short-Circuit Current CalculationIn general, to calculate a more conservative (higher) short-circuit current, the impedance tolerance valueis taken as a negative value, resulting in a smaller impedance value. However, in an IEC short-circuitcurrent calculation, if the Min (Exclude Duty Calc) option is selected in the Short-Circuit Current groupof the Star Mode Study Case Standard page, the impedance tolerance value will be taken as a positivevalue. This leads to a larger impedance value and lower short-circuit current.

Impedance Tolerance (Length)This group allows the user to consider tolerance adjustments to cable and transmission line length. Eachtolerance adjustment can be applied based on the individual equipment percent tolerance setting or basedon a globally specified percent value.

Cable LengthIf you select this option, the Star Mode Short-Circuit reduces cable length by the specified percenttolerance resulting in smaller impedance and consequently a higher fault current. For example, if thelength of the cable is 200 ft. and the tolerance is 5%, then the adjusted cable length used in the short-circuit calculation is 190 ft.

The Length Adjustment can be applied to individual cables by using the tolerance percent value specifiedon the Info page of the Cable Editor. A global cable length adjustment can be specified as well by



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selecting and specifying a global tolerance other than 0% in the corresponding field of Star ModeStudyCase editor Adjustment page. The global length adjustment overrides any individual cable tolerancevalue.

Transmission Line LengthIf you select this option, the Star Mode Short-Circuit reduces the transmission line length by the specified

percent tolerance resulting in smaller impedance and consequently a higher fault current. For example, ifthe length of the transmission line is 2 miles and the tolerance is 2.5%, then the adjusted transmission linelength used in the short-circuit calculation is 1.95 miles.

The length adjustment can be applied to individual lines by using the tolerance percent value specified onthe Info page of the Transmission Line Editor. A global transmission line length adjustment can bespecified as well by selecting and specifying a global tolerance other than 0% in the corresponding fieldon the Adjustment page of the Star Mode Study Case editor. The global length adjustment overrides anyindividual transmission line tolerance value.

Length Tolerance for IEC Minimum Short-Circuit Current CalculationIn general, to calculate a more conservative (higher) short-circuit current, the length tolerance value istaken as a negative value, resulting in shorter length. However, in IEC short-circuit current calculation, ifthe Min (Exclude Duty Calc) option is selected in the Short-Circuit Current group of the Star Mode StudyCase Standard page, the length tolerance value will be taken as a positive value. This leads to longerlength and lower short-circuit current.

Resistance Temperature CorrectionThis group allows the user to consider resistance correction based on the minimum operating temperaturefor cable and transmission line conductors. Each temperature resistance correction can be applied basedon the individual cable/line minimum temperature setting or based on a globally specified value.

Cable

This adjustment is applied to the cable conductor resistance. The Star Mode Short-Circuit adjusts theconductor resistance based on the minimum operating temperature. If the minimum operating temperatureis less than the rated base temperature of the conductor, then its resistance is reduced.

The temperature correction can be applied to individual cables by using the minimum operatingtemperature value specified on the Impedance page of the Cable Editor. A global temperature correctioncan be specified as well by selecting and specifying a global minimum temperature value in thecorresponding field on the Adjustment page of the Star Mode Study Case editor. The global temperaturecorrection value overrides any individual Cable Impedance Page minimum temperature. For moreinformation, see the Cable Editor Impedance Page Section in Chapter 11, AC Elements.

Transmission LineThis adjustment is applied to the transmission line conductor resistance. The Star Mode Short-Circuitadjusts the conductor resistance based on the minimum operating temperature. If the minimum operatingtemperature is less than the rated base temperature of the conductor, then the resistance is reduced.

The temperature correction can be applied to individual lines by using the minimum operatingtemperature value specified on the Impedance page of the Transmission Line Editor. A globaltemperature correction can be specified as well by selecting and specifying a global minimumtemperature value in the corresponding field on the Adjustment page of the Star Mode Study Case editor.The global temperature correction value overrides any individual Transmission Line Impedance page



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minimum temperature. For more information, see the Impedance Page in the Transmission Line EditorSection of Chapter 12, AC Elements.

IEC Minimum Short-Circuit Current CalculationIn general, to calculate a more conservative (higher) short-circuit current, the resistance temperaturecorrection is conducted according to the minimum operating temperature, resulting in a smaller resistancevalue. However, in an IEC short-circuit current calculation, if the Min (Exclude Duty Calc) option isselected in the Short-Circuit Current group of the Star Mode Study Case Standard page, the resistancetemperature correction will be conducted according to the maximum operating temperature. This leads toa higher resistance value and lower short-circuit current.

Fault ZfYou can consider fault impedance in the unbalanced fault calculations. In this group, you specify the faultimpedance to be applied to all the faulted buses. Depending on the type of faults applied to a bus, thespecified fault impedance is assumed to be between locations as given below:

• For a line-to-ground fault, the fault impedance is assumed to be between phase A and the ground.•

For a line-to-line fault, the fault impedance is assumed to be between phase A and phase B.• For a line-to-line-to-ground fault, the fault impedance is assumed to be between the ground and theshort-circuit point between phases A and B.

Include Fault Impedance ZfSelect this option to include fault impedance in the calculation. You can enter fault impedance in the Rand X text boxes.

R and XIn these two editor boxes, you enter the fault impedance in either Ohms or percent, depending on the faultimpedance unit selected. These values apply to all the faulted buses.

Ohm or %You can enter the fault impedance in either Ohms or percent. If the Ohm option is selected, the values inthe R and X editor boxes are in Ohms. If you select the percent option, the values in the R and X editor

boxes are in percent based on 100 MVA and the nominal kV of the faulted bus.



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Star Device Coordination Display Options

16.3 Display OptionsThe Display Options - Star (PD Coordination) editor consist of a Results page and pages for AC, AC-DC,and DC information annotations. The colors and displayed annotations selected for each study are specificto that study.

16.3.1 Results PageThe Results page of the Display Options is where you select different result annotations to be displayed inthe one-line diagram. Depending on short-circuit study type, ANSI or IEC, this page gives you differentoptions for 3-phase fault results. If the study type is for IEC short-circuit analysis, you will see the Results

page below.

Fault TypeSelect to display 3-Phase or Line-To-Ground currents on the one-line diagram. If 3-Phase is selected, theinitial symmetrical RMS is displayed on the diagram.

If Line-To-Ground is selected, then the currents and voltages displayed are dependent on the Line-To-Ground Fault group selection described below.

Line-To-Ground Fault



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Star Device Coordination Display Options

Fault I & VFor line-to-ground faults you have the options of displaying the total fault current for every faulted bus,along with the phase and sequence values for both current and voltage.

• You can select to display the value of three times the zero sequence current (3Io) in kA, as well as the phase B (Vb) Voltage in kV.

• You can select to display the positive sequence values for current (I1), negative sequence current (I2)and zero sequence current (I0) in kA, along with the positive sequence voltage (V1), negativesequence voltage (V2), and zero sequence voltage (Vo) in kV.

• You can select to display the fault current values for phases A, B, and C in kA along with theircorresponding phase voltages in kV.

If multiple buses are faulted, the program shows the individual branch contributions for 3-phase and line-to-ground-faults only at the faulted bus level. If only one bus is faulted at a time, ETAP shows individualcontributions from the entire system for all types of faults.



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Star Device Coordination Sequence of Operation

16.4 Star Sequence-of-operationWith ETAP Star, not only can you work with the time-current curves, you can also determine theoperating time of protective devices simply by placing a fault on the one-line diagram. The sequence-of-operations are automatically calculated and listed in an Event Viewer, which is dynamically linked withthe one-line diagram. This one-step concept utilizes the intelligent one-line diagram and performs acomplete set of actions to determine the operation of all protective devices. This includes internal shifting(normalizing) of each time-current characteristic curve based on the individual fault contribution level.

Sequence-of-Operation provides a system wide solution for an accurate and realistic operating time andstate of protective devices, such as relay, fuse, circuit breaker, trip devices, contactor, etc. The operationtime is calculated for each protective device based on its settings, time current characteristic, andinterlocks for a specified fault location and type.

Features & Capabilities• Graphically place a fault anywhere on the one-line diagram• Automatically calculate and display the fault current contributions on the one-line diagram• Determine the operating time and state of all protective devices based on the actual fault current

contribution flowing through each individual device• Globally view post fault actions and associated operating time via a tabulated event viewer• Graphically examine the operation of protective devices via the one-line diagram

16.4.1 Protective Device ActionsSequence-of-Operation study is essentially a time-domain simulation of protective devices action basedon a user-specified fault location and type. Protective device actions are determined at different timeinstants (events).

When a fault is placed on a valid bus or connector on the selected one-line diagram configuration, a short-circuit study is performed in accordance with the selected Star Mode study case parameters. Thecalculated the through fault currents of each valid protective device is then compared with its settings,time current characteristic, and applicable interlocks to determine the operating time band.

Protective device tripping actions can be categorized in two main groups• Integral Trip• Non-Integral Trip

Integral TripThe action of the integral trip components such as low voltage circuit breaker (trip device), fuse, overloadheater are base internal the tripping mechanisms or melting elements of the device which in turn cancause the device to operate by melting or tripping, respectively.

Non-Integral Trip Non-integral trip action of devices in power system is typically initiated by remote operation via a relayor shunt tripping by a sensing device. The operation of circuit breakers in power system are oftencontrolled via a relay or through a lock-out device. In the case of current sensing relays, the currenttransformer will sense the fault current based on its relative location to the fault and the magnitude as wellthe type of the fault current. When the operating current exceed that of the relay characteristic setting, therelay will signal its pre-programmed trip contacts to operate accordingly. For instance, a current relay will



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trip off circuit breakers once the measured current by relay exceeds a pre-set value. To use relay-controlled actions, you can add a relay and connect it to the one-line diagram via a PT or CT, dependingon type of the relay. Next in relay editor, user specifies relay-controlled device ID, action, time delay,and other data related to selected relay operation. During the SQOP simulation, if a relay setting is met,then its controlled device (i.e. HVCB) will take an action as specified in the relay editor. This methodavoids requesting to give a pre-defined action time and is a true resemblance to power system realoperating conditions.

The following table shows the list of relay-interlocked devices as well as their inherent operating timedelay.

Device Type Operating TimeANSI HVCB Operating cycles as specified in the HVCB editorIEC HVCB Min Delay as specified in the HVCB editorANSI LVCB (PBCB) 3 cycles – per IEEE Std 1584-2002ANSI LVCB (MCCB, ICCB) 1.5 cycle – per IEEE Std 1584-2002IEC LVCB Min Delay as specified in the LVCB editorSPST No time delay

Contactor Drop out time delay as specified in the Contactor editor

Note that the operating time for Close and Open actions are assumed to be the same.

16.4.2 Sequence-of-operation Events Viewer

HeaderThe first part of the header includes information regarding the type and location of the fault. The secondsection of the header includes information on data revision, system configuration, and date for which thestudy was performed.



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TimeTotal even time in mili-seconds. This is the total event time from the initiation of the fault in sequentialorder.

IDDisplays the protective device Identifier

If (kA)Through fault current in kA as seen by the protective device. The fault current component that is used todetermine the operating time of a protective device is based on the current sensing characteristic of thatdevice. For example, a fuse may operate for phase and ground fault current depending on the fault currentmagnitude where as a ground relay will only operate for ground fault. For relays the current sensingcharacteristics is defined by the relay trip elements such as Phase, Ground, Neutral, Sensitive Ground,

Negative Sequence, etc. Furthermore, the location and type of the CT connected to a relay determine thecurrent sensing characteristic of the relay. For example, a Negative Sequence trip element of a relay willoperate for negative sequence current (I 2) component of a ground fault. Similarly, for a ground fault, theground trip element of a low voltage solid-state trip device will operate for 3I 0 current component (whereas a phase trip element of the LVSST will operate for line current (Ia).

T1 (ms)Operating time event 1 for the protective device in mili-seconds. This is the initial tripping or minimumtime of the device where applicable. For example, T1 represents the minimum melting time of the fuse orthe minimum trip time of a thermal magnetic circuit breaker.

T2 (ms)Operating time event 2 in mili-seconds. This is the final tripping or maximum time of the device whereapplicable. For example, T1 represents the total clearing time of the fuse or the maximum trip time of athermal magnetic circuit breaker. Note that T2 will be zero for device with a single band or definiteoperating time (i.e. HVCB operating time).

ConditionThis column includes pertinent information regarding the device action. For relays this will include the

particular trip function and level for which the relay has operated on.

FooterInclude information on assumption or exception for sequence-of-operation analysis.



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Star Device Coordination Required Data

16.5 Required Data

Bus Data

Required data for short circuit (Clipping kA and Sequence-of-Operation) calculation for buses includes:• Nominal kV (when the prefault voltage option is set to use nominal kV)• %V (when the prefault voltage option is set to use bus voltage)• Type (such as MCC, switchgear, etc.) and continuous and bracing ratings

Branch DataBranch data is entered into the Branch editors (i.e., 3-Winding Transformer, 2-Winding Transformer,Transmission Line, Cable, Reactor, and Impedance). Required data for short circuit (Clipping kA andSequence-of-Operation) calculations for branches includes:

• Branch Z, R, X, Y, or X/R values and units, tolerance, and temperatures, if applicable• Cable and transmission line length and unit• Transformer rated kV and MVA• Base kV and MVA of impedance branches

For unbalanced short circuit (Clipping kA and Sequence-of-Operation) calculations you will also need:

• Zero sequence impedances• Transformer winding connections, grounding types, and grounding parameters

Power Grid DataRequired data for short circuit (Clipping kA and Sequence-of-Operation) calculations for utilities

includes:

• Nominal kV• %V and Angle• 3-Phase MVA sc and X/R

For unbalanced short circuit (Clipping kA and Sequence-of-Operation) calculations, you will also need:

• Grounding types and parameters• Single-Phase MVA sc and X/R

Synchronous Generator DataRequired data for short circuit (Clipping kA and Sequence-of-Operation) calculations for synchronousgenerators includes:

• Rated MW, kV, and power factor• Xd”, X d’, and X/R• Generator type• IEC exciter type



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• Grounding types and parameters• X0 (Zero Sequence Impedance)• X2 (Negative Sequence Impedance)

Inverter DataRequired data for short circuit (Clipping kA and Sequence-of-Operation) calculations for invertersincludes:

• Rated MW, kV, and power factor• K factor in the Rating page

Synchronous Motor DataRequired data for short circuit (Clipping kA and Sequence-of-Operation) calculations for synchronousmotor includes:

• Rated kW/hp and kV and the number of poles• Xd” and X/R• % LRC, X d, and T do’ for IEC standard


• Grounding types and parameters• X0 (Zero Sequence Impedance)• X2 (Negative Sequence Impedance)

Induction Motor DataRequired data for short circuit (Clipping kA and Sequence-of-Operation) calculations for inductionmotors includes:

• Rated kW/hp and kV• X/R plus one of the following:

Xsc at ½ cycle and 1.5-4 cycle if ANSI Short-Circuit Z option is set to Xsc, or%LRC if ANSI Short-Circuit Z option is set to Std MF% LRC, X d, and T d’ for IEC standard


• Grounding types and parameters• X0 • X2 (Negative Sequence Impedance)

Lumped Load DataRequired data for short circuit (Clipping kA and Sequence-of-Operation) calculations for lumped loadincludes:

• Rated MVA and kV



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• % motor load• % LRC, X/R, and Xsc for ½ cycle and 1.5-4 cycle• X’, X, and T d’ for IEC standard

Additional data for unbalanced short circuit (Clipping kA and Sequence-of-Operation) calculationsincludes:

• Grounding types and parameters

High Voltage Circuit Breaker DataRequired data for short circuit (Clipping kA and Sequence-of-Operation) calculations for high voltagecircuit breakers includes:

ANSI Standard Circuit Breaker:• Max kV• Rated Int. (rated interrupting capability)• Max Int. (maximum interrupting capability)• C & L rms (rms value of closing and latching capability)• C & L Crest (crest value of closing and latching capability)• Standard• Cycle

IEC Standard Circuit Breaker:• Rated kV• Min. Delay (minimum delay time in second)• Making (peak current)• AC Breaking (rms AC breaking capability)• Ithr (short circuit withstand current)• T

k (duration of short circuit withstand current)

ETAP calculates the interrupting capabilities of the circuit breaker from the rated and maximum interruptingcapabilities. This value is calculated at the nominal kV of the bus that the circuit breaker is connected to.

Low Voltage Circuit Breaker DataRequired data for short circuit (Clipping kA and Sequence-of-Operation) calculations for low voltagecircuit breakers includes:

ANSI Standard Circuit Breaker:• Type (power, molded case, or insulated case)• Rated kV• Interrupting (interrupting capability)• Test PF

IEC Standard Circuit Breaker:• Type (power, molded case, or insulated case)• Rated kV• Min. Delay (minimum delay time in second)• Making (peak current)



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• Breaking (rms AC breaking capability)• Ithr (short circuit withstand current)• Tk (duration of short circuit withstand current)

Trip Device• Trip device type library parameters• Device settings / TCC curves

Fuse DataRequired data for short circuit (Clipping kA and Sequence-of-Operation) calculations for fuses includes:

• Fuse library data including Size and TCC curves

ANSI Standard Fuse:• Fuse rated kV• Interrupting (interrupting capability)• Test PF

IEC Standard Fuse:• Fuse rated kV• Breaking (rms AC breaking capability)• Test PF

Overload Heater/49Required data for short circuit (Clipping kA and Sequence-of-Operation) calculations for OLH/49includes:

• Resistance / Tolerance•

OLH library parameters

CT/PT DataRequired data for short circuit (Clipping kA and Sequence-of-Operation) calculations for CT and PTincludes:

• Bus or Branch or Source or Load Connections• Rating (Ratio)

Relay/MVSST DataRequired data for short circuit (Clipping kA and Sequence-of-Operation) calculations for Relay includes:

• CT/PT Connections / Assignments• Interlocked Devices, Device ID, Action, Delay, Setting, Unit• Relay/MVSST Library parameters including settings and TCC curves

Other DataThere are some study case related data, which must also be provided, and you can enter this data into theStar Mode Study Case editor. The data includes:



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• Standard (ANSI/IEC)• XFMR tap option (transformer tap modeling method)• Prefault voltage• Fault Type (Phase / Ground) – Sequence-of-operation• Fault Value (Asym/Sym) – Sequence-of-operation• Bus levels to be considered – Sequence-of-operation• Faulted buses• Cable/OL heater (select this option to include cable and overload heater elements)• Adjustments



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Star Device Coordination Output Reports

16.6 Output ReportsETAP provides short circuit (Clipping kA and Sequence-of-Operation) clipping kA as well as Sequence-of-operation study output reports with different levels of detail, depending on your requirements. Thefollowing are just some examples that show this flexibility. ETAP 5.0 reports show total and individualfault current contributions for all the different types of faults.

16.6.1 View Output Reports From Study Case ToolbarThis is a shortcut for the Report Manger. When you click on the View Output Report button, ETAPautomatically opens the output report that is listed in the Study Case toolbar with the selected format. Inthe picture shown below, the output report name is SM and the selected format is Adjustments.

16.6.2 Star Mode Report ManagerTo open the Star Mode Report Manager, simply click on the Report Manager button on the Star ModeStudy toolbar. The editor includes four pages (Complete, Input, Result, and Summary) representingdifferent sections of the output report. The Report Manager allows you to select formats available fordifferent portions of the report and view it via Crystal Reports. There are several fields and buttonscommon to every page, as described below.

Output Report NameThis field displays the name of the output report you want to view.

Project File NameThis field displays the name of the project file based on which report was generated, along with thedirectory where the project file is located.

HelpClick on this button to access Help.



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OK/CancelClick on the OK button to close the editor and open the Crystal Reports view to show the selected portionof the output report. If no selection is made, it will simply close the editor. Click on the Cancel button toclose the editor without viewing the report.

16.6.3 Input Data PageThis page allows you to select different formats for viewing input data, grouped according to type,including Bus, Cable, Cover, Adjustments, Generator, Loads, Reactor, Transformer, UPS, and Utility.



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16.6.4 Results PageThis page allows you to select formats to view the short circuit (Clipping kA and Sequence-of-Operation)result portion of the output report. The same applies for IEC faults.



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16.6.5 Summary PageThis page allows you to select formats to view summary reports of the output report. Note that ifsequence-of-operation study output report is selected, the Summary page will include an additional reportfor Sequence-of-operation summary.



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Complete PageIn this page you can select the Complete report in Crystal Reports format, which brings up the completereport for the short circuit (Clipping kA and Sequence-of-Operation) study. The complete report includesinput data, results, and summary reports.

Documents

Ch16 Star Devcoord