This chapter introduces the project, which is to create an advanced user guide for the ETAP software to analyze power system protection designs. The guide will explain how to create a one-line diagram, configure protection equipment, perform fault and short circuit analysis. The objectives are to help engineers learn and apply ETAP, while the constraints include completing all tasks by the deadline and within budget.

1. PROTECTIVE DEVICE
COORDINATION
Héctor Rivera

2. POYTECHNIC UNIVERSITY OF PUERTO RICO
ELECTRICAL ENGINEERING DEPARTMENT
HATO REY, PUERTO RICO
PROTECTIVE DEVICE COORDINATION
GROUP 28
Rivera, Héctor J.
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3. Table of Contents
Table of Pictures ............................................................................................................................. 5
Chapter 1: General Information ...................................................................................................... 8
1.1 Abstracto ..................................................................................................................... 10
1.2 Abstract ....................................................................................................................... 11
1.3 Introduction ................................................................................................................. 12
1.4 Objectives ................................................................................................................... 14
1.5 Constraints .................................................................................................................. 15
Chapter 2: ETAP User Guide ....................................................................................................... 16
2.1 Basic ETAP User Guide ............................................................................................. 18
2.1.1 Creating a new ETAP Project. ............................................................................. 22
2.1.2 Opening an ETAP existing Project. ..................................................................... 23
2.1.3 Building New one-line Diagrams. ....................................................................... 25
2.1.4 Connecting Elements. .......................................................................................... 28
2.1.5 Adding a Protective Device to your One-Line. ................................................... 28
2.1.6 Verify if the element is connected. ...................................................................... 29
2.2 Advance ETAP User Guide ........................................................................................ 30
2.2.1 How to configure the elements in the one-line diagram. ..................................... 34
A) Utility ................................................................................................................. 34
B) High Voltage Circuit Breakers ........................................................................ 36
C) Low Voltage Circuits Breakers ....................................................................... 39
D) Protective Relay ................................................................................................ 44
E) Fuses Ratings .................................................................................................... 49
F) Transformer Properties: .................................................................................. 54
G) Load Properties: ............................................................................................... 57
H) Bus ...................................................................................................................... 58
2.2.2 Perform a Fault Analysis; .................................................................................... 59
Chapter 3: Transformer Case Study.............................................................................................. 61
3.1 Diagrams ..................................................................................................................... 64
3.2 Equipment Data .......................................................................................................... 66
3.3 Calculations ................................................................................................................ 68
3.4 Coordination Using ETAP Program ........................................................................... 73
3.5 Fault Simulation .......................................................................................................... 77
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4. 3.6 Settings and Results .................................................................................................... 81
Chapter 4: Bayamón WWTP Coordination Study........................................................................ 84
4.1 Scope ........................................................................................................................... 88
4.2 Electrical System Oneline Diagram ............................................................................ 90
4.3 Imput Data Report ...................................................................................................... 94
4.4 Calculations ................................................................................................................ 97
4.5 Short Circuit Study ................................................................................................... 138
4.6 Power Fuses Selection for Power Transformers T1, T2, T3, T4, T5, T6 and T7 ..... 160
4.7 Protection Relay Settings for ................................................................................. 173
Distribution Feeders ..................................................................................................... 173
4.8 Relay Settings ........................................................................................................... 178
4.9 Results ....................................................................................................................... 181
Chapter 5: Protective Device Coordination Project Results ....................................................... 186
5.1 Alternatives Considered ............................................................................................ 188
5.2 System Specifications ............................................................................................... 191
Operation .................................................................................................................... 193
Protective relay ........................................................................................................... 193
Distance relay ............................................................................................................ 195
Magazine Article............................................................................................................. 197
5.4 Budget ....................................................................................................................... 198
5.5 Bibliography ............................................................................................................. 199
5.6 Conclusion ................................................................................................................ 201
Chapter 6: Administrative Section .............................................................................................. 202
6.1 Protective Device Coordination Project Proposal..................................................... 205
Work Schedule ............................................................................................................ 217
Progress Report ............................................................................................................... 222
Work Schedule ................................................................................................................ 241
Appendix ..................................................................................................................................... 246
Tables and Curves ........................................................................................................... 247
Protection Relay Settings for Generators ........................................................................ 252
A.3 General Information ................................................................................................. 255
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5. Table of Pictures
Fig. 2.1: Create New Project Panel.................................................................................................... 22
Fig. 2.2: User Information Panel ....................................................................................................... 22
Fig. 2.3: Starting up window ............................................................................................................. 23
Fig. 2.4: Open Panel .......................................................................................................................... 24
Fig. 2.5: Selecting Project.................................................................................................................. 24
Fig. 2.6: Mode Toolbar ...................................................................................................................... 25
Fig.2.7: ETAP Elements .................................................................................................................... 27
Fig. 2.8: Connecting Elements .......................................................................................................... 28
Fig. 2.9: Open Panel .......................................................................................................................... 28
Fig. 2.10: Elements not connected..................................................................................................... 29
Fig. 2.11: Power Grid Editor Window .............................................................................................. 34
Fig. 2.12: High Voltage Circuit Breaker Editor Window .................................................................. 36
Fig. 2.13: Circuit Breaker Library ..................................................................................................... 37
Fig. 2.14: Low Voltage Circuit Breaker Window ............................................................................. 39
Fig. 2.15: Low Voltage Circuit Breaker library ................................................................................ 41
Fig. 2.16: Overcurent Relay Editor Window ..................................................................................... 44
Fig. 2.17: Overcurrent Settings Panel ................................................................................................ 45
Fig. 2.18: Instantaneus Settings Panel ............................................................................................... 46
Fig. 2.19: Fuse Editor Window ......................................................................................................... 49
Fig. 2.20: Fuse Library Window ....................................................................................................... 51
Fig. 2.21: Winding Transformer Editor Window .............................................................................. 54
Fig. 2.22: Transformer Rating Editor Window ................................................................................. 55
Fig. 2.23: Transformer Tap Editor Window ...................................................................................... 56
Fig. 2.24: Lumped Load Editor Window........................................................................................... 57
Fig. 2.25: Bus Editor Window ........................................................................................................... 58
Fig. 2.26: Fault Simulation ................................................................................................................ 59
Fig. 2.27: Select Sequence Viewer to find fault analysis results ....................................................... 60
Fig. 2.28: Results Window ................................................................................................................ 60
Fig. 3.1: Transformer Protection Diagram……………………………………………………....... 65
Fig. 3.2: Selected Fuse…………………………………………………………………………….. 67
Fig. 3.3: Selected Relay…………………………………………………………………………… 67
Fig. 3.4: Table of Current Transformer Specifications…………………………………………… 67
Fig. 3.5: Table of Power Fuse Rating……………………………………………………………... 71
Fig. 3.6: Overcurrent Relay Settings at Transformer……………………………………………... 74
Fig. 3.7: Overcurrent Relay Settings at Load 1,2…………………………………………………. 75
Fig. 3.8: Fuse Settings…………………………………………………………………………….. 76
Fig. 3.9: ETAP Simulation of Fault at Bus 1……………………………………………………… 78
Fig. 3.10: Sequence of Operation Events at Bus 1………………………………………………... 78
Fig. 3.11: ETAP Fault Simulation at Bus 2……………………………………………………….. 79
Fig. 3.12: Sequence of Operation Events at Bus 2………………………………………………... 79
Fig. 3.13: ETAP Fault Simulation at Load 1……………………………………………………… 80
Fig. 3.14: Sequence of Operation Events at Load 1………………………………………………. 80
Fig. 3.15: Relay and Fuse Settings………………………………………………………………... 83
Fig. 3.16: Results of Short Circuit Analysis………………………………………………………. 83
Fig. 4.1: Power Transformer Characteristics Table……………………………………………….. 89
Fig. 4.2: Generator Characteristics Table…………………………………………………………. 89
Fig. 4.3: Original Oneline Diagram of Bayamón WWTP………………………………………… 92
Fig. 4.4: Suggested Oneline Diagram of Bayamón WWTP………………………………………. 93
Fig. 4.5: Lines Cables……………………………………………………………………………... 95
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6. Fig. 4.6: Existing Transformer Line Cable. …………………………………………………….... 95
Fig. 4.7: Generator Cables………………………………………………………………………… 95
Fig. 4.8: Positive Sequence impedance Diagram at Bus 1……………………………………....... 99
Fig. 4.9: Three Phase Fault at Bus 1…………………………………………………………… 102
Fig. 4.10: Positive Sequence Impedance Diagram at Bus 2…………………………………… 103
Fig. 4.11: Three Phase Fault at Bus 2 …………………………………………………………… 104
Fig. 4.12: Positive Sequence Impedance Diagram at Load 1……………………………………. 105
Fig. 4.13: Three Phase Fault at Load 1…………………………………………………………... 106
Fig. 4.14: Positive Impedance Diagram at Load 5………………………………………………. 107
Fig. 4.15: Three Phase Fault at Load 6…………………………………………………………... 108
Fig. 4.16: Positive Sequence Impedance Diagram at Bus 1 for a Line to Ground Fault………... 109
Fig. 4.17: Cero Sequence Impedance Diagram at Bus 1……………………………………........ 109
Fig. 4.18: Line to Ground Fault at Bus 1………………………………………………………… 110
Fig. 4.19: Positive Sequence Impedance Diagram at Bus 2 for a Line to Ground Fault………... 111
Fig. 4.20: Cero Sequence Impedance Diagram at Bus 2………………………………………… 111
Fig. 4.21: Line to Ground Fault at Bus 2………………………………………………………… 112
Fig. 4.22: Positive Sequence Impedance Diagram at Load 1 for a Line to Ground Fault………. 113
Fig. 4.23: Cero Sequence Impedance Diagram at Load 1……………………………………….. 113
Fig. 4.24: Line to Ground Fault at Load 1……………………………………………………….. 114
Fig. 4.25: Positive Sequence Impedance Diagram at Load 5 for a Line to Ground Fault………. 115
Fig. 4.26: Cero Sequence Impedance Diagram at Load 5……………………………………….. 115
Fig. 4.27: Line to Ground Fault. At Load 5……………………………………………………... 116
Fig. 4.28: Positive Sequence Impedance Diagram at Generator Bus……………………………. 117
Fig. 4.29: Positive Sequence Impedance Diagram at Bus 2 using Generators………………….. 118
Fig. 4.30: Positive Sequence Impedance Diagram at Load 1 using Generators………………… 119
Fig. 4.31: Positive Sequence Impedance Diagram at Load 5 using Generators………………… 120
Fig. 4.32: Positive Sequence Impedance Diagram at Generators Bus for a Line to Ground Fault. 121
Fig. 4.33: Cero Sequence Impedance Diagram at Generators Bus………………………………. 121
Fig. 4.34: Positive Sequence Impedance Diagram at Bus 2 Using Generators for a Line to Ground
Fault……………………………………………………………………………………………… 122
Fig. 4.35: Cero Sequence Impedance Diagram at Bus 2 Using Generators……………………... 123
Fig. 4.36: Positive Sequence Impedance Diagram at Load 1 Using Generators for a Line to Ground
Fault……………………………………………………………………………………………… 124
Fig. 4.37: Cero Sequence Impedance Diagram at Load 1 Using Generators……………………. 124
Fig. 4.38: Positive Sequence Impedance Diagram at Load 5 Using Generators for a Line to Ground
Fault……………………………………………………………………………………………… 125
Fig. 4.39: Cero Sequence Impedance Diagram at Load 5 Using Generators……………………. 125
Fig. 4.40: Fault Simulation at Primary Side of 38KV/4.16KV Utility Transformer of BWWTP. 140
Fig. 4.41: Sequence of Operations Events at Primary Side of T1……………………………….. 141
Fig. 4.42: Fault Simulation at Bus 1 of BWWTP………………………………………………... 144
Fig. 4.43: Sequence of Operation Events at Bus 1………………………………………………. 145
Fig. 4.44: Fault Simulation at Bus 2 of BWWTP………………………………………………... 148
Fig. 4.45: Sequence of Operation Events at Bus 2………………………………………………. 149
Fig. 4.46: Fault Simulation at Load 1 of BWWTP……………………………………………… 152
Fig. 4.47: Sequence of Operations Events at Load 1……………………………………………. 153
Fig. 4.48: Fault Simulation at Load 6 of BWWTP……………………………………………… 156
Fig. 4.49: Sequence of Operation Events at Load 6……………………………………………... 157
Fig. 4.50: Recommendations to Fuse Protection………………………………………………… 161
Fig. 4.51: Time Fuse 1 and 5 Coordination……………………………………………………… 162
Fig. 4.52: Characteristics Curves for Fuse 1 and 5……………………………………………… 163
Fig. 4.53: Fuse 1 and 5 recommended…………………………………………………………… 164
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7. Fig. 4.54: Time Fuse 2 and 6 Coordination……………………………………………………… 165
Fig. 4.55: Characteristics Curves for fuse 2 and 6………………………………………………. 166
Fig. 4.56: Fuse 2 and 6 Recommended………………………………………………………….. 166
Fig. 4.57: Time Fuse 3, 4, 7 and 8 Coordination………………………………………………… 167
Fig. 4.58: Characteristics Curves for fuses 3, 4, 7 and 8………………………………………… 168
Fig. 4.59: Fuse 3, 4, 7 and 8 Recommended……………………………………………….......... 169
Fig. 4.60: Time Fuse 9 Coordination……………………………………………………………. 170
Fig. 4.61: Characteristics Curves for fuse 9……………………………………………………... 171
Fig. 4.62: Fuse 9 Recommended………………………………………………………………… 172
Fig. 4.63: Relay 351A Settings…………………………………………………………………... 179
Fig. 4.64: Overcurent Relay Settings for Generator……………………………………………... 180
Fig. 4.65: Undervoltage, Overvoltage, Frequency of Power Relay for Generator………………. 180
Fig. 4.66: Three Phase Fault Results…………………………………………………………….. 183
Fig. 4.67: Line to Ground Fault Results…………………………………………………………. 184
Fig. 4.68: Three Phase Fault Results Using Generators…………………………………………. 185
Fig. 4.69: Line to Ground Fault Results Using Generators…………………………………........ 185
Fig. 6.1: Protective Devices……………………………………………………………... 213
Fig. 6.2: Budget to Complete Design……………………………………………………. 218
Fig. 6.3: Salary Cap……………………………………………………………………… 218
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8. Chapter 1: General Information
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9. Contents
1.1 Abstracto……………………………………………………………………………... 10
1.2 Abstract………………………………………………………………………………. 11
1.3 Introduction…………………………………………………………………………... 12
1.4 Objectives…………………………………………………………………………….. 14
1.5 Constraints…………………………………………………………………………..... 15
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10. 1.1 Abstracto
La protección de los sistemas de potencia es uno de los campos más importantes
dentro del área de potencia en la ingeniería eléctrica. A través del tiempo se han creado
muchísimos programas de computadora con el fin de analizar diseños eléctricos. Nuestro
proyecto consiste en preparar una guía de usuario fácil de entender acerca de un programa
existente, llamado ETAP, diseñado para realizar análisis de protección de sistemas de
potencia. Esta guía de usuario debe incluir como crear un diagrama monolineal, como
configurar los equipos de protección, y también la forma correcta de hacer un análisis de
fallas y de corto circuito. Finalmente, nosotros preparamos una guía de usuario avanzada
con explicaciones detalladas sobre aplicaciones especiales y conceptos técnicos manejados
en el programa ETAP. También, como requisito de nuestro proyecto se analiza un caso
estudio de un sistema de potencia y se realiza la coordinación de protección del mismo.
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11. 1.2 Abstract
Power Protection is one of the most important fields in Power Electrical
Engineering. Through time many software’s has been created to analyze electrical designs.
Our project consist of prepare a user guide easy to understand of how to use an existing
power protection analysis program calling ETAP. This user guide must include how to
create a one-line diagram, how to configure power system devises, and an explanation of
the right way to perform a short and fault analysis. Finally, we prepare an advance user
guide with detailed explanations of special features and technical concept of ETAP
program. Also, as a requirement of our project, we analyzed a case study of power system
and perform the protective device coordination of it.
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12. 1.3 Introduction
Electricity has been a subject of scientific interest since at least the early 17th
century. Probably the first electrical engineer was William Gilbert who designed the
versorium: a device that detected the presence of statically charged objects. He was also the
first to draw a clear distinction between magnetism and static electricity and is credited
with establishing the term electricity. However it was not until the 19th century that
research into the subject started to intensify. Notable developments in this century include
the work of Georg Ohm, who in 1827 quantified the relationship between the electric
current and potential difference in a conductor, Michael Faraday, the discoverer of
electromagnetic induction in 1831, and James Clerk Maxwell, who in 1873 published a
unified theory of electricity and magnetism in his treatise on Electricity and Magnetism.
They are the fathers of electrical engineering and the electric systems.
Today, power system protection is that part of electrical power engineering that
deals with protecting the electrical power system from faults by isolating the faulted part
from the rest of the network.
Any electric power system involves a large amount of auxiliary equipment for the
protection of generators, transformers, and the transmission lines. Circuit breakers are
employed to protect all elements of a power system from short circuits and overloads, and
for normal switching operations.
The principle of a protection scheme is to keep the power system stable by isolating
only the components that are under fault, even as leaving as much of the network as
possible still in operation. Thus, protection schemes must apply a very pragmatic and
pessimistic approach to clearing system faults. For this reason, the technology and
philosophies utilized in protection schemes are often old and well-established because they
must be very reliable.
In much the same way as the early computers of the 1950s and 1960s were a
precursor to the computational capabilities of today’s computers. Specialized hardwire
systems were developed for locally monitoring the operation of power plants and for
remotely monitoring and controlling switches in transmission substation. The Remote
Terminal Units of these early monitoring systems were implemented with relay logic, while
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13. the master station consisted primarily of large banks of annunciator panels with red and
green light indication the state of the points being monitored with flashing light indication a
change in state or an alarm condition.
The impact of computers has nowhere been more revolutionary than in electrical
engineering. The design, analysis and operation of electrical and electronic systems has
become completely dominated by computers, a transformation that has been motivated by
the natural ease of interface between computers and electrical systems, and the promise of
spectacular improvements in speed and efficiency.
Our project consists of develop a protective device coordination using a graphical
software program to add features and flexibility in the area of electrical system protection.
Also, this graphical software program it’s going to be using for all kind of element that
used these. We will select the software program, analyze all types of element protection
that are utilizing in electrical systems, and simulate the program using various management
studies.
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14. 1.4 Objectives
• To make a research about technical references of fuses, relays and breakers.
• Understand technical data format of protection devices.
• To learn how to use the protective device coordination program.
• Create a user guide easy to understand about how to use software program.
• Build an advance use guide to explain additional features of software program.
• Perform a case study with the software program.
• Establish the system coordination of a case study with the program.
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15. 1.5 Constraints
• How to install ETAP program.
• Ways to use library of ETAP program. Start by understanding.
• Interpret results in the program.
• Establish coordination of a protection system.
• Run the program with all kind of requisites.
• Find right protective devices for design coordination.
• Understand how to program protective devices settings of equipments to use.
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16. Chapter 2: ETAP User Guide
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17. Contents
Basic ETAP User Guide………………………………………………………………………... 18
Creating a new ETAP Project………………………………………………………………….. 22
Opening an ETAP existing Project..……… ………………………………………… 23
Building New one-line Diagram. ……………………………………………………... 25
Connecting Elements……………………………………………………………… 28
Adding Protective Device to your One-Line………………………………………. 28
Verify if the element is connected………………………………………………… 29
Advance ETAP User Guide…..…………………………………………………………... 30
How to configure the elements in the one-line diagram…………………………… 34
Utility……………………………………………………………………… 34
High Voltage Circuit Breakers……………………………………………... 36
Low Voltage Circuit Breaker………………………………………………. 39
Protective Relay……………………………………………………………. 44
Fuses Ratings………………………………………………………………. 49
Transformer Properties………………………………………………..……. 54
Load Properties…………………………………………………………….. 57
Bus…………………………………………………………………………. 58
Perform a Fault Analysis…………………………………………………………... 59
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18. 2.1 Basic ETAP User Guide
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19. Page 19 of 263

20. Contents
Creating a new ETAP Project. ...................................................................................................... 22
Opening an ETAP existing Project. .............................................................................................. 23
Building New one-line Diagrams. ................................................................................................ 25
Connecting Elements. ................................................................................................................... 28
Adding a Protective Device to your One-Line. ............................................................................ 28
Verify if the element is connected. ............................................................................................... 29
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21. Table of Figure
Fig. 2.1: Create New Project Panel .................................................................................................... 22
Fig. 2.2: User Information Panel ....................................................................................................... 22
Fig. 2.3: Starting up window ............................................................................................................. 23
Fig. 2.4: Open Panel .......................................................................................................................... 24
Fig. 2.5: Selecting Project.................................................................................................................. 24
Fig. 2.6: Mode Toolbar ...................................................................................................................... 25
Fig.2.7: ETAP Elements .................................................................................................................... 27
Fig. 2.8: Connecting Elements .......................................................................................................... 28
Fig. 2.9: Open Panel .......................................................................................................................... 28
Fig. 2.10: Elements not connected..................................................................................................... 29
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22. 2.1.1 Creating a new ETAP Project.
Open the program and select new project. Write the name of the new project and select ok.
Fig. 2.1: Create New Project Panel
Write the name of the project user and select the access level permissions.
Fig. 2.2: User Information Panel
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23. 2.1.2 Opening an ETAP existing Project.
Select open on the ETAP screen.
Fig. 2.3: Starting up window
To open an existing project must be selected the icon showed. Click the icon and select
the project that you want to run in program.
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24. For example, select document named Protection System Devices and wait until in the next
page appears (Fig. 2.5)
Fig. 2.4: Open Panel
Select icon that has the ETAP symbols. Then click open to see the project at ETAP main
window.
Fig. 2.5: Selecting Project
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25. 2.1.3 Building New one-line Diagrams.
To build or edit a one-line diagram in ETAP, you must be in Edit Mode. Click the Edit
button on the Mode toolbar.
Fig. 2.6: Mode Toolbar
AC Elements:
= Pointer = Bus
= 2 winding transformers = 3 winding transformers
= cable = Transmission Line
= Reactors, Current-Limiting = Impedance
= Power grid = Generator
= Wind turbine Generator = Induction Machine
= Synchronous Motor = Lumped Load
= MOV = Static Load
= Capacitor = Harmonic Filter
= Remote Connector = Static Var Compensator
= HV DC Transmission Link = AC Composite Motor
= Composite Network = Fuse
= Contactor = High Voltage Circuit
Breaker
= Low Voltage circuit Breaker = Single Throw Switch
= Double Throw Switch = Instrumentation
= Ground Grid = Display options
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26. = Schedule Report Manager = Current Transformer (CT)
= Potential Transformer (PT) = Voltmeter
= Ammeter = Multi-meter
= Voltage Relay = Reverse Power Relay
= Frequency Relay = MV solid State Trip
Relay
= Motor Relay = Overcurrent Relay
= Overload Heater = Multi-Function Relay
= Tag Link
DC Elements:
= Pointer = Bus
= DC Cable = DC Impedance
= DC-DC Converter = Battery
= DC Motor = DC static Load
= DC Lumped Load = Composite CSD
= DC Composite Motor = Composite Network
= DC Circuit Breaker = DC Fuse
= DC Single Throw Switch = DC Double Throw
Switch
= Un-Interrupted Power System = Variable Frequency Drive
= Charger = Inverter
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27. You can select the element that your project requires for run the short circuit analysis. In
the columns you can see all the elements that ETAP program has. Select the elements and
drop to the board to complete your diagram.
Fig.2.7: ETAP Elements
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28. 2.1.4 Connecting Elements.
To connect the elements in the one-line. Use the mouse pointer over the connection pin of
an element, and it will turn red. Then click and drag to the connection pin of another
element. Follow this procedure to connect all the elements on the one-line. In the case of
buses, the entire element graphic functions as a connection point.
Fig. 2.8: Connecting Elements
2.1.5 Adding a Protective Device to your One-Line.
To connect the element between two elements does not require delete the line connecting
the elements. The element will automatically connect to the line. As shown in the diagram.
Fig. 2.9: Open Panel
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29. 2.1.6 Verify if the element is connected.
To check if an element is energized click on the continuity icon ( )
located in the project toolbar. All elements that are not energized will
be grayed out. For example, with the continuity check on, open CB4.
As shown in the figure to the right, CB4 and elements downstream
are grayed out.
Fig. 2.10: Elements not connected
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30. 2.2 Advance ETAP User Guide
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31. Page 31 of 263

32. Contents
How to configure the elements in the one-line diagram. .............................................................. 34
A) Utility ............................................................................................................................. 34
B) High Voltage Circuit Breakers ....................................................................................... 36
C) Low Voltage Circuits Breakers ...................................................................................... 39
D) Protective Relay ............................................................................................................... 44
E) Fuses Ratings .................................................................................................................... 49
F) Transformer Properties: ................................................................................................. 54
G) Load Properties: .............................................................................................................. 57
H) Bus ..................................................................................................................................... 58
Perform a Fault Analysis; ............................................................................................................. 59
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33. Table of Figures
Fig. 2.11: Power Grid Editor Window .............................................................................................. 34
Fig. 2.12: High Voltage Circuit Breaker Editor Window .................................................................. 36
Fig. 2.13: Circuit Breaker Library ..................................................................................................... 37
Fig. 2.14: Low Voltage Circuit Breaker Window ............................................................................. 39
Fig. 2.15: Low Voltage Circuit Breaker library ................................................................................ 41
Fig. 2.16: Overcurent Relay Editor Window ..................................................................................... 44
Fig. 2.17: Overcurrent Settings Panel ................................................................................................ 45
Fig. 2.18: Instantaneus Settings Panel ............................................................................................... 46
Fig. 2.19: Fuse Editor Window ......................................................................................................... 49
Fig. 2.20: Fuse Library Window ....................................................................................................... 51
Fig. 2.21: Winding Transformer Editor Window .............................................................................. 54
Fig. 2.22: Transformer Rating Editor Window ................................................................................. 55
Fig. 2.23: Transformer Tap Editor Window ...................................................................................... 56
Fig. 2.24: Lumped Load Editor Window........................................................................................... 57
Fig. 2.25: Bus Editor Window ........................................................................................................... 58
Fig. 2.26: Fault Simulation ................................................................................................................ 59
Fig. 2.27: Select Sequence Viewer to find fault analysis results ....................................................... 60
Fig. 2.28: Results Window ................................................................................................................ 60
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34. 2.2.1 How to configure the elements in the one-line diagram.
A) Utility
Rated kV
Enter the rated voltage of the power grid in kilovolts (kV).
Fig. 2.11: Power Grid Editor Window
Generation Categories
This group is used to assign the different power settings to each of the ten generation
categories for this power grid. Each grid can be set to have a different operating power
level for each generation category. Depending on the operation mode, some of the values
become editable as follows:
• Swing Mode: %V and angle
• Voltage Control Mode: %V and MW
• Mvar Control: MW and Mvar
• Power Factor Control: MW and PF
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35. SC Rating MVAsc
Specify the short-circuit MVA for three-phase and single-phase (line-to-ground) faults. As
you enter or modify MVAsc or X/R, ETAP recalculates the corresponding short-circuit
impedance values.
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36. B) High Voltage Circuit Breakers
How to change the Rating
• Click on either the ANSI or IEC option button to select that standard.
Fig. 2.12: High Voltage Circuit Breaker Editor Window
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37. Library Info
To access ANSI standard library data, click on the ANSI selection and then click on the
Library button. Use the same procedure for accessing IEC standard library data. As you
change the standard from ANSI to IEC, the data fields change accordingly.
Rating, ANSI Standard
Click on ANSI to enter high voltage circuit breaker ratings according to the ANSI
standards. Select the manufacturer and breaker model.
Fig. 2.13: Circuit Breaker Library
Max kV
Select the rated maximum kV of the high voltage circuit breaker in rms kV or select the
rating from the list box.
Continuous Amp
Select the continuous current rating of the high voltage circuit breaker in amperes or select
the rating from the list box.
Standard
Select the high voltage circuit breaker type as Symmetrical or Total rated from the list box.
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38. Cycle
Select the rated interrupting time for AC high voltage circuit breakers in cycles from the list
box.
CB Cycle Description
2 2-cycle ac high voltage circuit breakers with 1.5-cycle Minimum Contact Parting Time
3 3-cycle ac high voltage circuit breakers with 2-cycle Minimum Contact Parting Time
5 5-cycle ac high voltage circuit breakers with 3-cycle Minimum Contact Parting Time
8 8-cycle ac high voltage circuit breakers with 4-cycle Minimum Contact Parting Time
Rated Interrupting
Enter the rated short-circuit current (rated interrupting capability) at the rated maximum kV
in rms kA or select the rating from the list box.
Maximum Interrupting
Enter the maximum symmetrical interrupting capability in rms kA or select the rating from
the list box.
C & L RMS
Enter the closing and latching capability of the high voltage circuit breaker in asymmetrical
rms kA. This value is equal to 1.6 times the maximum interrupting capability.
C & L Crest
Enter the closing and latching capability of the high voltage circuit breaker in crest kA.
This value is equal to 2.7 times the maximum interrupting capability.
Page 38 of 263

39. C) Low Voltage Circuits Breakers
Standard
Click on either the ANSI or IEC option button to select that standard. Note: once the
breaker is selected from the breaker Library Quick Pick the standard is set based on the
library entry and is display only.
Type
Select a type from the drop-down list and display the type of breaker. Low voltage circuit
breakers include Molded Case, Power, and Insulated Case breakers. Once the breaker is
selected from the breaker Library Quick Pick, the LVCB type is set based on the library
entry and is display only.
Fig. 2.14: Low Voltage Circuit Breaker Window
Page 39 of 263

40. CB and Trip Device library
The low voltage circuit breaker data for a selected standard and type can be selected by
clicking on the Library button.
Standard
Click on either the ANSI or IEC option to select that standard. Note that the Standard
selection in the breaker library Quick Pick (and hence the breaker models displayed) will be
defaulted to the selection.
AC/DC
Displays that the LV breaker is AC. This option is grayed out and is not available for
editing.
Type
Select from the drop down list and display the breaker type. The LV breaker types include
Molded Case, Power and Insulated Case breakers. Note that the Type selection in the
breaker library Quick Pick (and hence the breaker models displayed) will be defaulted to
the selection made for the breaker type on the Rating page. The breaker type selection can
be changed on the Quick Pick if desired.
Page 40 of 263

41. Manufacturer Name
This displays a list of all AC LV breaker manufacturers included in the library for the
selected breaker standard and type. To choose one, just select the manufacturer name.
Fig. 2.15: Low Voltage Circuit
Breaker library
Reference
This displays the Manufacturer reference, if available. For example, Westinghouse is the
reference for Cutler Hammer.
Page 41 of 263

42. Model Name
The Model section displays list of all models for the selected standard, breaker type and
breaker manufacturer. The models are displayed in the form of Model – Max kV – Pole,
which forms a unique record name in the breaker library. Select the Model – Max kV –
Pole by highlighting it.
ANSI Short-Circuit data
When ANSI standard is selected, the short-circuit data shows the applied voltage in kV,
short-circuit interrupting current for the applied voltage in kA, and test power factor in %,
for all breaker types. The short-circuit parameters are explained in more detail in the
Ratings section. Select a desired applied voltage and short-circuit data by highlighting it.
Size
This displays a list of all sizes available for the selected Model, Max. kV, and Pole record
for the breaker. To select a size from the Library Quick Pick, highlight the size.
Ratings, ANSI Standard
Click on ANSI standard button and choose the breaker type to enter the ratings for LV
circuit breaker in accordance with the ANSI/IEEE standards. When a breaker is selected
from Library Quick Pick, all parameters shown below will be set to their corresponding
values chosen from the Quick Pick. With the exception of Size, changing the values after
selecting a breaker from Library Quick Pick will turn the header blue to indicate that the
substituted library data has been modified.
Size
Select an item from the drop-down list to display the size in amperes for the selected
breaker.
Page 42 of 263

43. Continuous Amp
Select an item from the drop-down list or enter the continuous current rating for the low
voltage circuit breaker in amperes. The Continuous Amp value will be set equal to the
breaker size when a breaker is selected from the breaker Library Quick Pick.
Rated kV
Select an item from the drop-down list or enter the rated kV rating for the low voltage
circuit breaker in kV. When a breaker is selected, the rated kV value will be set equal to
the applied kV selected from Library.
Test PF
This is the power factor of test equipment on which the rating of the circuit breaker has
been established. When a breaker is selected, the Test PF is set to the Test PF value
selected from Library.
Fused
For all breaker types, select fused or unfused by clicking on the provided selection box.
Note that when a breaker is selected from library, the Fused checkbox is set to the status as
selected from the Quick Pick. The value of Test PF will change appropriately for fused or
unfused type, in case of Power breakers.
Interrupting kA
Select from drop down list or enter the Interrupting kA rating for the low voltage circuit
breaker in kA. Note that when a breaker is selected, the interrupting kA value will be set
equal to the kA value for selected applied kV from library Quick Pick.
Page 43 of 263

44. D) Protective Relay
Fig. 2.16: Overcurent Relay Editor Window
Library
To access the Overcurrent relay library data, click on the Library button. Clicking the
Library button displays the relay library Quick Pick. From the Library, select the relay by
highlighting the Manufacturer name and Model name. Then click on the OK button to
retrieve the selected data from the library and transfer it to the editor.
OC level
Overcurrent relays can have multiple Time overcurrent (TOC) and/or Instantaneous
overcurrent (IOC) elements that can simultaneously and independently set in the relay
library. The OC level displays a drop down list of the maximum number of overcurrent
levels that are available for the selected relay.
Page 44 of 263

45. Overcurrent (51) Settings
The Time overcurrent settings available for Phase, Neutral, Ground, Sensitive Ground and
Negative Sequence are described below.
Fig. 2.17: Overcurrent Settings
Panel
Pickup Range
Select from drop down list and display the Time overcurrent Pickup range for the selected
curve. The pickup range can be specified in amperes of the secondary or primary current
rating. It can also be in multiples/percent of the CT secondary.
Pickup Setting
For the selected pickup range, select or enter the Time overcurrent pickup setting. The
pickup setting can be discrete values or continuously adjustable.
Relay Amps
This field displays the relay secondary current in amperes, for the selected pickup setting.
Prim. Amps
This field displays the relay primary current in amperes, for the selected pickup setting.
Page 45 of 263

46. Time Dial
Select and display the Time Dial for the selected curve type. The time dial can be discrete
values or continuously adjustable.
Instantaneous (50) Settings
The Instantaneous settings available for Phase, Neutral, Ground, Sensitive Ground and
Negative Sequence are described below.
Fig. 2.18: Instantaneus Settings Panel
Page 46 of 263

47. Curve Type
This field with a drop down list of curves is available only if the selected relay has Short
time feature and if the Short time is selected. Select from the drop down list and display
the Short time curve type for the selected model.
Pickup Range
Select from the drop down list and display the Instantaneous Pickup range (for the selected
curve in case of Short time). The pickup range can be specified in amperes of the
secondary or primary current rating. It can also be in multiples/percent of the CT secondary
or 51 pickup.
Pickup Setting
For the selected pickup range, select or enter the Instantaneous pickup setting. The pickup
setting can be discrete values or continuously adjustable.
Relay Amps
This field displays the relay secondary current in amperes, for the selected pickup setting.
Prim. Amps
This field displays the relay primary current in amperes, for the selected pickup setting.
Delay Range
This field is available only if the relay has Instantaneous function. Select from the drop
down list and display the Instantaneous Delay range. The delay range could either be in
seconds or cycles.
Delay
Select or enter the intentional delay for the instantaneous. The Delay can be in seconds or
cycles, depending on the selection of relay. The delay can be in the form of discrete values
or continuously adjustable.
Page 47 of 263

48. Time Dial
This field is available only if the selected relay has Short time feature and if the Short time
is selected. Select or enter the Time Dial for the selected curve type. The time dial can be
discrete values or continuously adjustable.
Page 48 of 263

49. E) Fuses Ratings
Standard
Click either the ANSI or IEC button option to select that standard. Once the fuse is
selected from the Library Quick Pick - Fuse, the standard is set based on the library entry
and is display only.
Rating, ANSI Standard
Click on ANSI standard to enter the ratings for Fuse in accordance with the ANSI/IEEE
standards. When a Fuse is selected from library Quick Pick, all parameters shown below
will be set to their corresponding values chosen from the Quick Pick. With the exception of
Size, changing the value(s) after selecting a fuse from library Quick Pick will turn the
header to blue color indicating that the substituted library data has been modified.
Fig. 2.19: Fuse Editor Window
Page 49 of 263

50. kV
Select from drop down list or enter the rated kV rating for the Fuse in kV. When a Fuse is
selected, the Rated kV value will be set equal to the Max. kV selected from library Quick
Pick.
Size
Select from the drop-down list and display the size in amperes for the selected fuse. Note:
the Size field will be empty when no fuse is chosen from Library Quick Pick.
Continuous Amp
Select from drop down list or enter the continuous current rating for the Fuse in amperes.
The Continuous Amp value will be set equal to the fuse size when a fuse is selected from
library Quick Pick.
Interrupting
Select from the drop-down list or enter the Interrupting kA rating for the Fuse in kA. Note:
when a Fuse is selected, the interrupting kA value will be set equal to the kA value for
selected fuse size from Library Quick Pick.
Test PF
Enter the power factor of test equipment on which the rating of the fuse has been
established. When a fuse is selected, the Test PF is set to the Test PF value selected from
library Quick Pick.
Page 50 of 263

51. Library (Quick Pick)
To select a fuse from the library, click the Library button and the Library Quick Pick – Fuse
dialog box will appear. From the dialog box, select a fuse by selecting the Manufacturer
name and the desired fuse Model, Max kV, and Speed. This represents a unique record.
Select the desired size and short circuit interrupting kA. Then click the OK button to
retrieve the selected data from the library and transfer it to the editor.
Fig. 2.20: Fuse Library Window
Standard
Click on either the ANSI or IEC option to select that standard. Note that the Standard
selection in the Fuse library Quick Pick (and hence the fuse models displayed) will be
defaulted to the selection made for the standard on the Rating page. The standard selection
can be changed on the Quick Pick if desired.
Page 51 of 263

52. Manufacturer
Manufacturer Name
Displays a list of all AC Fuse manufacturers included in the library for the selected
standard. Select the manufacturer by highlighting the manufacturer name.
Reference
Displays a manufacturer reference, if available, for selected manufacturer. For example,
Siemens is the reference manufacturer for ITE.
Model Name
The Model section displays list of all fuse models for the selected standard and fuse
manufacturer. The models are displayed in the form of Model – Max kV – Speed, which
forms a unique record name in the fuse library. Select the Model – Max kV – Speed by
highlighting it.
Cont. Amp
This displays the ampere value corresponding to each size for the selected fuse model.
Int. kA (ANSI Standard)
This displays the short-circuit interrupting rating in kA corresponding to each size for the
selected ANSI fuse model.
Model Info
Class
This displays the class (E-rated, for example) for the selected fuse model.
Page 52 of 263

53. Type
This displays the type (Power Fuse, for example) for the selected fuse model.
Brand Name
It shows the brand name, if available, for the selected fuse model.
Reference
It demonstrates the reference, if available, for selected fuse model.
Application
Present the application for the selected fuse model.
Page 53 of 263

54. F) Transformer Properties:
You can open the editor for T2 and go to the Rating page. On the rating page you can enter
the value of the primary kV, secondary kV, primary winding rating in kVA or MVA, and
the maximum transformer rating. Additionally, you can enter the impedance or substitute
typical values for the transformer.
Fig. 2.21: Winding Transformer Editor Window
Page 54 of 263

55. Transformer Ratings
Fig. 2.22: Transformer Rating Editor Window
Rating of Transformer:
Enter the rating of KV primary and secondary.
Enter the rating of MVA.
Enter the Typical X/R.
Enter the Z variation and Z Tolerance.
You may select the typical rating.
Page 55 of 263

56. Transformer Tap
The Transformer Tap Optimization calculation optimizes a unit transformer tap, or
equivalently, its turn ratio, to ensure that the generator unit voltage remains within its upper
and lower variation range (typically 95% to 105%), while producing its full MW and Mvar
capability under the system voltage variation.
Fig. 2.23: Transformer Tap Editor Window
Page 56 of 263

57. G) Load Properties:
In this part you can go to the Nameplate page. The available fields in the rating section depend
on the Model Type selected. In the Ratings section enter the lumped load rating in MVA or
MW. Furthermore, the % loading for various loading categories can be specified here.
Fig. 2.24: Lumped Load Editor Window
Page 57 of 263

58. H) Bus
Nominal kV
Enter the nominal voltage of the bus in kilovolts (kV).
In/Out of Service
The operating condition of a bus can be selected by choosing either the In Service or Out of
Service option.
Fig. 2.25: Bus Editor Window
Page 58 of 263

59. 2.2.2 Perform a Fault Analysis;
Star View:
Click Star Protective Device Coordination.
Fig. 2.26: Fault Simulation
Page 59 of 263

60. Select Sequence Viewer to find the result of the Protective Device Cordination.
Fig. 2.27: Select Sequence Viewer to
find fault analysis results
It will show the results to be show in the report. The sequence of operation is on order to
the parameters of the system.
Fig. 2.28: Results Window
Page 60 of 263

61. Chapter 3: Transformer Case
Study
Page 61 of 263

62. Contents
Diagrams………………………………………………………………………………… ..64
Equipment Data……………………………………………………………………………66
Calculations………………………………………………………………………………..68
Coordination Using ETAP Program……………………………………………………….73
Fault Simulation……………………………………………………………………………77
Results………………...……………………………………………………………………81
Page 62 of 263

63. Table of Figures
Fig. 3.1: Transformer Protection Diagram……………………………………………………....... 65
Fig. 3.2: Selected Fuse…………………………………………………………………………….. 67
Fig. 3.3: Selected Relay…………………………………………………………………………… 67
Fig. 3.4: Table of Current Transformer Specifications…………………………………………… 67
Fig. 3.5: Table of Power Fuse Rating……………………………………………………………... 71
Fig. 3.6: Overcurrent Relay Settings at Transformer……………………………………………... 74
Fig. 3.7: Overcurrent Relay Settings at Load 1,2…………………………………………………. 75
Fig. 3.8: Fuse Settings…………………………………………………………………………….. 76
Fig. 3.9: ETAP Simulation of Fault at Bus 1……………………………………………………… 78
Fig. 3.10: Sequence of Operation Events at Bus 1………………………………………………... 78
Fig. 3.11: ETAP Fault Simulation at Bus 2……………………………………………………….. 79
Fig. 3.12: Sequence of Operation Events at Bus 2………………………………………………... 79
Fig. 3.13: ETAP Fault Simulation at Load 1……………………………………………………… 80
Fig. 3.14: Sequence of Operation Events at Load 1………………………………………………. 80
Fig. 3.15: Relay and Fuse Settings………………………………………………………………... 83
Fig. 3.16: Results of Short Circuit Analysis………………………………………………………. 83
Page 63 of 263

64. 3.1 Diagrams
Page 64 of 263

65. 3.1.1 Transformer Case Study Diagram:
Fig. 3.1: Transformer Protection Diagram
Our Transformer Case Study has the following components:
a) One transformer 38/4.16 KV of 7.5/11.3 MVA.
b) Two feeders.
Protection has to be able to extinguish faults that affect the system. It scheme consist of
protective relaying and fuses. Coordination criteria have 22 cycles between protection levels.
We considered selectivity, reliability and simplicity to accomplish with a scheme protection
safety.
Page 65 of 263

66. 3.2 Equipment Data
Page 66 of 263

67. Equipment Data:
Specification of electric fuse
Fuse
Continuous Maximum
Fuse Name Size Type
Amperes KV
Cutler Hammer Standard
150E 150 17
BA-200 Speed
Fig. 3.2: Selected Fuse
Relay settings
Relay
TOU
IOU
Location Relay Name 51 & Curve
50 & 50N
51N
ABB 51D
0.5-80; 0.5-80; Extremely
Feeder with 50
0.1 steps 0.1 steps Inverse
(60Hz)
ABB 51D
Main 0.5-80; 0.5-80; Very
with 50
Breaker 0.1 steps 0.1 steps Inverse
(60Hz)
Fig. 3.3: Selected Relay
Selected current transformer
Current Transformer
Location CTR Type
Main
2,500/5 MR C400
Breaker
Load 800/5 MR C400
Fig. 3.4: Table of Current Transformer Specifications
Page 67 of 263

68. 3.3 Calculations
Page 68 of 263

69. Power System Coordination calculation:
1) Calculating the short circuit current:
375MVA
ISC = = = 5, 697.53 A
3(38 KV )
7.5MVA
IBASE = = 113.95 A
3(38 KV )
5, 697.53
I pu = = 50.0 pu
113.95
1
Z pu = = 0.02 pu
50.0
1∠00
ISC = = 11.11 p
0.02 + 0.07
 38 
IBASE = (113.95)   = 11,564.3 A
 4.16 
Page 69 of 263

70. 2) Calculating the multiples of the relay in the load, to verify the necessary time dial in the
curves:
11, 565.3
M= = 13.6
850
3) Obtaining the pick-up current for the relay in the transformer:
Pickup = (1568.28)(1.2) = 1881.93A
4) The multiples of the current transformer (CTM) in the transformer:
11,565.3
M= = 6.14
1,881.93
5) The calculation for choose the CTR:
CTR = 2000/5
11.3MVA
IFL = = 1, 568.28 A ISC = 11,565.04
3(4.16 KV )
a) CTR > 1,568.28(1.2) = 1,881.93A
b) ISC/CTR < 100 A
11,565.04/400 < 100
Page 70 of 263

71. 6) Calculation for choosing fusible:
Using the standard Speed curve
Step 1: Full load Current
11.3MVA 7.5MVA
IFL = = 171.68 A INM = = 113.95 A
3(38 KV ) 3(38 KV )
Data: 46 Kv Power Fuses (Show & Standard Speed)
Rating Continuous Current Operating Time
100E 165 See curves…
125E 181 See curves…
Fig. 3.5: Table of Power Fuse Rating
F1 ≥ 125E
Step 2: Inrush Current
IINRUSH = 113.95(12) = 1,367.48 A @ 6 cycles F1 ≥ 100E
Step 3: Short circuit current
11,564.3
ISC = = 1, 266.1A @ 43.2 cycles F1 ≥ 175E
 38 
 
 4.16 
Step 4: Turning Ratio
 I NOMINAL 
FR =   > 1.5 < 3
 I NOMINAL TRANS. 
 213 
=  = 1.86 1.5 < 1.86 < 3
 113.95 
The fuse chosen is 175E because it complied with the parameters of the design. Fuse will be
175E and can handle 213 Amps.
Page 71 of 263

72. Using the Slow Speed curve:
Step 1: Full load Current
11.3MVA
IFL = = 171.68 A
3(38 KV )
Data: 46 Kv Power Fuses (Slow & Standard Speed)
Rating Continuous Current Operating Time
100E 165 See curves…
125E 181 See curves…
Fig. 3.5: Table of Power Fuse Rating
F1 ≥ 125E
Step 2: Inrush Current
IINRUSH = 113.95(12) = 1,367.48 @ 6 ciclos F1 ≥ 80E
Step 3: Short circuit current
11,564.3
ISC = = 1, 266.1A @ 43.2 ciclos F1 ≥ 125E
 38 
 
 4.16 
Step 4: Turning Ratio
 I NOMINAL 
FR =   > 1.5 < 3
 I NOMINAL TRANS. 
 181 
=  = 1.58 1.5 < 1.58 < 3
 113.95 
The fuse chosen is 125E because it complied with the parameters of the design.
Page 72 of 263

73. 3.4 Coordination Using ETAP
Program
Page 73 of 263

74. Overcurrent:
To protect our transformer power system we choose a relay distributed by ABB
with overcurrent and instantaneous settings. This setting for overcurrent was given using a
Definite Time Curve. The pick range is specified by 5 amperes of the secondary or primary
rating. Using this setting the relay will operate when primary current exceed 2,500A. Time
dial of overcurrent relay is given by curve type and changing it by time required. In the
other side, to operate instantaneous relay is necessary select a pick up according to short
circuit current. These input settings are introduced at ETAP window showing below.
Overcurrent Relay settings in the transformer:
Fig. 3.6: Overcurrent Relay Settings at Transformer. In this
case the curve selected was Definite Time.
Page 74 of 263

75. Another section of our power system that required protection are load 1 and 2
feeders. To protect these feeders we select an ABB instantaneous and overcurrent relay.
The overcurrent settings were chosen by a Definite Time Curve. The pick range is
specified by 5 amperes of the secondary side of relay. Using this setting the overcurrent
will operate when line current exceed 850A. Time dial is given by relay curve according to
time required for current magnitude. In the other side, to operate instantaneous relay is
necessary select a pick up according to short circuit current. When current reach 11,568;
instantaneous protection must operate. These input settings are introduced at ETAP
window showing below.
Overcurrent relay setting at load 1,2:
Fig. 3.7: Overcurrent Relay Settings at Load 1,2
Page 75 of 263

76. Fuse Setting:
In order to perform good protective device coordination is necessary implement use of
almost one fuse. The fuse selected by us is S&C, SMU-20. It is modeling by an standard
speed curve with short circuit current of 10KA. Also it has a maximum rated voltage of
38KV. Finally, the size of fuse is 200E with a 200 continuous amperes.
Fig. 3.8: Fuse Settings
Page 76 of 263

77. 3.5 Fault Simulation
Page 77 of 263

78. Short circuit results:
Fig. 3.10: Sequence of Operation
Events at Bus 1
Fig. 3.9: ETAP Simulation of
Fault at Bus 1
Protection in the system can not protect for a fault at bus 1. It should be protected
by other protective device out of our system.
Page 78 of 263

79. Figures below show short circuit results at bus 2 when operate the instantaneous
relay 2. The instantaneous relay work to open the circuit and if it does not operate fuse 1
operate to disconnect system. Relay 2 operates at 2.75 cycles after a fault occurs. If relay 1
does not work, fuse 1 is going to operate at 52.56 cycles.
Fig. 3.12: Sequence of Operation Events at
Fig. 3.11: ETAP Fault Simulation at Bus 2 Bus 2
Page 79 of 263

80. In figures below you can see short circuit results at load 1. Instantaneous relay 3 will open
first. If it does not operate, time overcurrent relay 2. But, if it also does not work, fuse 1
must open with a time delay.
Fig. 3.14: Sequence of Operation Events at
Load 1
Fig. 3.13: ETAP Fault Simulation at Load 1
ETAP program gives results of short circuit. Short circuit current is 21,570 at load 1.
With this current we choose settings for relay 3. Short circuit at load 1 is the same results
at load 2.
Sequence operation work with a sequence coordination of 22 cycles approximated.
Relay 3 operates at 7.74 cycles covered by relay 2 witch operates at 28.86 cycles like
primary protection.
Page 80 of 263

81. 3.6 Settings and Results
Page 81 of 263

82. Settings and Results
We perform protective device coordination for a transformer and two loads. In
order to express our results and recommendations clearly, we organized all data in tables.
These tables include devices and fuse settings. In the figure 3.15 you can find curves type,
pick-up and time dial to obtain better results with the protective device coordination. In the
other side, three phase fault table contents short circuits results in different section of
system.
The figure 3.16 shows short circuit current magnitude in different parts of system.
First, the table presents a three phase fault at feeder #1. Short circuit current at this point is
11,564A. With this fault feeder relay will operates at 2.76 cycles like primary protection.
If the feeder relay does not operate, main breaker feeder will operate at 25.86 cycles.
When system has a fault at primary side of transformer #1, the fuse will operate at
52.56 cycles.
Relays in our system use definite time curve. It is use to chose time dial of relay
operation. In the other way, fuse 1 is modeling with a standard speed curve. Using these
settings the protection is complete according with coordination criteria.
Page 82 of 263

83. Equipment Settings
Equipment Settings
Time
Equipment Curve Pick-up
Dial
Feeder Definite
2,500 1.895
Relay Time
Main
Definite
Breaker 850 1.895
Time
Relay
Standard
Fuse X X
Speed
Fig. 3.15: Relay and Fuse Settings
Fault Results
Three Phase Fault
Short Operation Protection Devices
Localization
Circuit Feeder Main
Fault
Current Relay Breaker Fuse
(51) Relay (51)
Feeder #1 or 11,564
2.76 25.86 52.56
#2 A
11,566
Bus #2 X 2.76 52.56
A
10,500
T1 Primary X X 52.56
A
T1 Secondary 9,950 A X X X
Fig. 3.16: Results of Short Circuit Analysis
Page 83 of 263

84. Chapter 4: Bayamón WWTP
Coordination Study
Page 84 of 263

85. Contents
Scope……………………………………………………………………………………….. 88
Electrical System Oneline Diagram……………………………………………………….... 90
Imput Data Report………………………………………………………………………… 94
Calculations………………………………………………………………………………... 97
Short Circuit Study………………………………………………………………………. 138
Power Fuse Selection for Power Transformer T1, T2, T3, T4, T5, T6 and T7………….. 160
Protection Relay Settings for Distrbution Feeders………………………………………. 173
Relay Settings……………………………………………………………………………. 178
Results……………………………………………………………………………………. 181
Page 85 of 263

86. Table of Figure
Fig. 4.1: Power Transformer Characteristics Table………………………………………………... 89
Fig. 4.2: Generator Characteristics Table…………………………………………………………. 89
Fig. 4.3: Original Oneline Diagram of Bayamón WWTP………………………………………… 92
Fig. 4.4: Suggested Oneline Diagram of Bayamón WWTP………………………………………. 93
Fig. 4.5: Lines Cables……………………………………………………………………………... 95
Fig. 4.6: Existing Transformer Line Cable. ……………………………………………………… 95
Fig. 4.7: Generator Cables………………………………………………………………………… 95
Fig. 4.8: Positive Sequence impedance Diagram at Bus 1………………………………………... 99
Fig. 4.9: Three Phase Fault at Bus 1……………………………………………………………... 102
Fig. 4.10: Positive Sequence Impedance Diagram at Bus 2……………………………………... 103
Fig. 4.11: Three Phase Fault at Bus 2 …………………………………………………………… 104
Fig. 4.12: Positive Sequence Impedance Diagram at Load 1……………………………………. 105
Fig. 4.13: Three Phase Fault at Load 1…………………………………………………………... 106
Fig. 4.14: Positive Impedance Diagram at Load 5………………………………………………. 107
Fig. 4.15: Three Phase Fault at Load 6…………………………………………………………... 108
Fig. 4.16: Positive Sequence Impedance Diagram at Bus 1 for a Line to Ground Fault………... 109
Fig. 4.17: Zero Sequence Impedance Diagram at Bus 1……………………………………........ 109
Fig. 4.18: Line to Ground Fault at Bus 1………………………………………………………… 110
Fig. 4.19: Positive Sequence Impedance Diagram at Bus 2 for a Line to Ground Fault………... 111
Fig. 4.20: Zero Sequence Impedance Diagram at Bus 2………………………………………… 111
Fig. 4.21: Line to Ground Fault at Bus 2………………………………………………………… 112
Fig. 4.22: Positive Sequence Impedance Diagram at Load 1 for a Line to Ground Fault………. 113
Fig. 4.23: Zero Sequence Impedance Diagram at Load 1……………………………………….. 113
Fig. 4.24: Line to Ground Fault at Load 1……………………………………………………….. 114
Fig. 4.25: Positive Sequence Impedance Diagram at Load 5 for a Line to Ground Fault………. 115
Fig. 4.26: Zero Sequence Impedance Diagram at Load 5……………………………………….. 115
Fig. 4.27: Line to Ground Fault. At Load 5……………………………………………………... 116
Fig. 4.28: Positive Sequence Impedance Diagram at Generator Bus……………………………. 117
Fig. 4.29: Positive Sequence Impedance Diagram at Bus 2 using Generators………………….. 118
Fig. 4.30: Positive Sequence Impedance Diagram at Load 1 using Generators………………… 119
Fig. 4.31: Positive Sequence Impedance Diagram at Load 5 using Generators………………… 120
Fig. 4.32: Positive Sequence Impedance Diagram at Generators Bus for a Line to Ground Fault 121
Fig. 4.33: Zero Sequence Impedance Diagram at Generators Bus……………………………… 121
Fig. 4.34: Positive Sequence Impedance Diagram at Bus 2 Using Generators for a Line to Ground
Fault……………………………………………………………………………………………… 122
Fig. 4.35: Zero Sequence Impedance Diagram at Bus 2 Using Generators……………………... 123
Fig. 4.36: Positive Sequence Impedance Diagram at Load 1 Using Generators for a Line to Ground
Fault……………………………………………………………………………………………… 124
Fig. 4.37: Zero Sequence Impedance Diagram at Load 1 Using Generators……………………. 124
Fig. 4.38: Positive Sequence Impedance Diagram at Load 5 Using Generators for a Line to Ground
Fault……………………………………………………………………………………………… 125
Fig. 4.39: Zero Sequence Impedance Diagram at Load 5 Using Generators……………………. 125
Fig. 4.40: Fault Simulation at Primary Side of 38KV/4.16KV Utility Transformer of BWWTP. 140
Fig. 4.41: Sequence of Operations Events at Primary Side of T1……………………………….. 141
Fig. 4.42: Fault Simulation at Bus 1 of BWWTP………………………………………………... 144
Fig. 4.43: Sequence of Operation Events at Bus 1………………………………………………. 145
Fig. 4.44: Fault Simulation at Bus 2 of BWWTP……………………………………………….. 148
Fig. 4.45: Sequence of Operation Events at Bus 2………………………………………………. 149
Fig. 4.46: Fault Simulation at Load 1 of BWWTP……………………………………………… 152
Page 86 of 263

87. Fig. 4.47: Sequence of Operations Events at Load 1……………………………………………. 153
Fig. 4.48: Fault Simulation at Load 6 of BWWTP……………………………………………… 156
Fig. 4.49: Sequence of Operation Events at Load 6……………………………………………... 157
Fig. 4.50: Recommendations to Fuse Protection………………………………………………… 161
Fig. 4.51: Time Fuse 1 and 5 Coordination……………………………………………………… 162
Fig. 4.52: Characteristics Curves for Fuse 1 and 5……………………………………………… 163
Fig. 4.53: Fuse 1 and 5 recommended…………………………………………………………… 164
Fig. 4.54: Time Fuse 2 and 6 Coordination……………………………………………………… 165
Fig. 4.55: Characteristics Curves for fuse 2 and 6………………………………………………. 166
Fig. 4.56: Fuse 2 and 6 Recommended………………………………………………………….. 166
Fig. 4.57: Time Fuse 3, 4, 7 and 8 Coordination………………………………………………… 167
Fig. 4.58: Characteristics Curves for fuses 3, 4, 7 and 8………………………………………… 168
Fig. 4.59: Fuse 3, 4, 7 and 8 Recommended……………………………………………….......... 169
Fig. 4.60: Time Fuse 9 Coordination……………………………………………………………. 170
Fig. 4.61: Characteristics Curves for fuse 9……………………………………………………... 171
Fig. 4.62: Fuse 9 Recommended………………………………………………………………… 172
Fig. 4.63: Relay 351A Settings………………………………………………………………….. 179
Fig. 4.64: Overcurent Relay Settings for Generator……………………………………………... 180
Fig. 4.65: Undervoltage, Overvoltage, Frequency of Power Relay for Generator………………. 180
Fig. 4.66: Three Phase Fault Results…………………………………………………………….. 183
Fig. 4.67: Line to Ground Fault Results…………………………………………………………. 184
Fig. 4.68: Three Phase Fault Results Using Generators…………………………………………. 185
Fig. 4.69: Line to Ground Fault Results Using Generators…………………………………........ 185
Page 87 of 263

88. 4.1 Scope
Page 88 of 263

89. Scope
Develop a short circuit study for Power Transformers and relay settings for a waste
water treatment plant and the protective devices associated.
The Bayamón Waste Water Treatment Plant has seven large power
transformers with their respective protective devices (power fuses or
protective relaying) in service. The intention of this short circuit study is to
verify the appropriated protective device coordination and recommended the
appropriated changes if any.
For this plant we will cover the relay coordination and settings for the
protective device associated.
The short circuit current available at Bayamón Waste Water Treatment
Plant, with 38 kV connection tap, is submitted by Puerto Rico Electric
Authority (PREPA). Three phase short circuit current is 20,000 A and
11,547 A for phase to ground.
The ETAP Power Simulation computer program, version 5.5 from Operation
Technology, Inc was used for all the short circuit studies and simulations.
The following tables detail information available for the electrical
Fig. 4.1: Power equipment from the electrical drawings for Bayamón Waste Water
Transformer Treatment Plant. This information will be the data base for the short circuit
Characteristics
Table study.
Power Transformer
# T1 T2 T3 T4 T5 T6 T7
Characteristics
1 Voltage in kV 38/4.16 4.16/0.48 4.16/0.48 38/4.16 4.16/0.48 4.16/0.48 4.16/0.48
2 Capacity in MVA 5 1.5 1.5 5 1.5 1.5 0.15
3 Impedance in % 6.21 3 3 6.21 3 3 2.5
4 Connection D-Y D-Y D-Y D-Y D-Y D-Y D-Y
# Generator (1 to 2) Value Units SEL 300G
Characteristics
1 Terminal Voltage 4.16 kV
2 Capacity 2500 KW
3 Power Factor 0.8 Fig. 4.2: Generator
Characteristics
4 Full Load 347.37 Amps Table.
5 Synchronous Reactance 2.14
6 Transient Reactance 0.19
7 Substransient Reactance 0.14
8 Negative Sequence Reactance 0.19
9 Zero Sequence Reactance 0.05
Page 89 of 263

90. 4.2 Electrical System Oneline
Diagram
Page 90 of 263

91. Diagrams
We were required to perform an analysis for choose necessary equipment to protect
electric power system o Bayamón Waste Water Treatment Plant. After analizing the
system, we decided to use following coordination equation; t2 = 1.3t1 +15. Using it, we set
next coordination level between 23 to 25 cycles.
In order to find the best devices to perform a good protective device coordination,
we analized a lot of different devices. The selected devices are commonly used in power
systems. It help very much to find devices information. Selected fuses were exclusive to
accomplish all requirements. Chosen devices and results are showed through next pages.
Page 91 of 263

92. Bayamón WWTP Case Study
Fig. 4.3: Original Oneline Diagram of
Bayamón WWTP.
This is the original oneline diagram given to us with the objective of perform the
protective device coordination. It does not include any protective device.
Page 92 of 263

93. Bayamón WWTP Sugested Oneline Diagram
Fig. 4.4: Suggested Oneline Diagram of
Bayamón WWTP.
Above diagram shows all suggested protective devices for power system of
Bayamón WWTP. Each device was selected to guarantee the best protective device
coordination. Shortly we present complete analysis of this coordination.
Page 93 of 263

94. 4.3 Input Data Report
Page 94 of 263

95. Data:
Lines cables 500 MCM TRXLPE
Z+ =(32+j36) µΩ/ft Z0 =(104+j18) µΩ/ft
Lines Distance R+ X+ R0 X0
L1 120’ 0.00384 0.00432 0.01248 0.00216
L2 120’ 0.00384 0.00432 0.01248 0.00216
L3 1000’ 0.032 0.036 0.104 0.018
L4 15’ 0.032 0.036 0.104 0.018
L5 15’ 0.00048 0.00054 0.00156 0.00027
L6 15’ 0.00048 0.00054 0.00156 0.00027
L7 15’ 0.00048 0.00054 0.00156 0.00027
L8 15’ 0.00048 0.00054 0.00156 0.00027
Fig. 4.5: Lines Cables. This table includes power system feeders’
parameters.
Line cable 2/0 AWG Cu TRXLPE
Z+ =(103+j44) µΩ/ft Z0 =(400+j25) µΩ/ft
Lines Distance R+ X+ R0 X0
L9 100’ 0.0103 0.0044 0.04 0.0025
Fig. 4.6: Existing Transformer Line Cable. The figure presents cable
characteristics of an existing transformer.
Generators cables 350 MCM TRXLPE
+
Z =(42+j38) µΩ/ft Z0 =(154+j20) µΩ/ft
Lines Distance R+ X+ R0 X0
LG1 75’ 0.00315 0.00285 0.01155 0.0015
LG2 75’ 0.00315 0.00285 0.01155 0.0015
Fig. 4.7: Generator Cables. Table above shows parameters of cables using
for generators.
Page 95 of 263

96. Project: ETAP Page: 1
5.5.0C
Location: Date: 04-16-2007
Contract: SN: BETA-ELECT
Engineer: Revision: Base
Study Case: SM
Filename: JHD-CS Config.: Normal
2-Winding Transformer Input Data
Transformer Rating Z Variation % Tap Setting Adjusted Phase Shift
ID MVA Prim. kV Sec. kV %Z X/R + 5% - 5% % Tol. Prim. Sec. %Z Type Angle
T1 5.000 38.000 4.160 6.21 12.14 0 0 0 0 0 6.2100 Std Pos. Seq. -30.0
T2 1.500 4.160 0.480 3.00 7.10 0 0 0 0 0 3.0000 Std Pos. Seq. -30.0
T3 1.500 4.160 0.480 3.00 7.10 0 0 0 0 0 3.0000 Std Pos. Seq. -30.0
T4 5.000 38.000 4.160 6.21 12.14 0 0 0 0 0 6.2100 Std Pos. Seq. -30.0
T5 1.500 4.160 0.480 3.00 7.10 0 0 0 0 0 3.0000 Std Pos. Seq. -30.0
T6 1.500 4.160 0.480 3.00 7.10 0 0 0 0 0 3.0000 Std Pos. Seq. -30.0
T7 0.150 4.160 0.480 2.50 20.00 0 0 0 0 0 2.5000 Std Pos. Seq. -30.0
2-Winding Transformer Grounding Input Data
Grounding
Transformer Rating Conn. Primary Secondary
ID MVA Prim. kV Sec. kV Type Type kV Amp Ohm Type kV Amp Ohm
T1 5.000 38.000 4.160 D/Y Solid
T2 1.500 4.160 0.480 D/Y Solid
T3 1.500 4.160 0.480 D/Y Solid
T4 5.000 38.000 4.160 D/Y Solid
T5 1.500 4.160 0.480 D/Y Solid
T6 1.500 4.160 0.480 D/Y Solid
T7 0.150 4.160 0.480 D/Y Solid
Page 96 of 263

97. 4.4 Calculations
Page 97 of 263

98. Impedance:
Distance at lines.
Line1 = Line2 = 120 ' Line3 = Line4 = 1000 ' Line5−8 = 15' Line9 = 100 '
LineG1 = LineG 2 = 75'
The cable used is TRXLPE 500 MCM.
µΩ
Z + LINE1−2 = (32 + j 36) (120 ')
ft
Z + LINE1− 2 = (0.00384 + j 0.00432)Ω
µΩ
Z 0 LINE1−2 = (104 + j18) (120 ')
ft
Z 0 LINE1− 2 = (0.01248 + j 0.00216)Ω
 Ω 
Z 0 LINE1− 2 =  (1.04 + j 0.18) 
 1000 ' 
Z 0 LINE1− 2 = (0.1248 + j 0.0216)Ω
 µΩ 
Z + LINE 3− 4 =  (32 + j 36)  (1000 ')
 ft 
Z + LINE 3− 4 = (0.032 + j 0.036)Ω
 µΩ 
Z 0 LINE 3−4 =  (104 + j18)  (1000 ')
 ft 
Z 0 LINE 3− 4 = (0.104 + j 0.018)Ω
µΩ
Z + LINE 5−8 = (32 + j 36) (15')
ft
Z + LINE 5−8 = (0.00048 + j 0.00054)Ω
µΩ
Z 0 LINE 5−8 = (104 + j18) (15')
ft
Z 0 LINE 5−8 = (0.00156 + j 0.00027)Ω
µΩ
Z + LINE 9 = (103 + j 44) (100 ')
ft
Z + LINE 9 = (0.0103 + j 0.0044)Ω
µΩ
Z 0 LINE 9 = (400 + j 25) (100 ')
ft
Z 0 LINE 9 = (0.04 + j 0.0025)Ω
Page 98 of 263

99. Generators and Cable Equipment Electrical Specification:
The cable used is TRXLPE 350 MCM.
Ω
Z + LINE −G1 = Z + LINE −G 2 = (42 + j 38) (75')
1000 '
Z + LINE −G1 = Z + LINE −G 2 = (0.00315 + j 0.00285)Ω
Ω
Z 0 LINE −G1 = Z 0 LINE −G 2 = (154 + j 20) (75')
1000 '
Z 0 LINE −G1 = Z 0 LINE −G 2 = (0.01155 + j 0.0015)Ω
Page 99 of 263

100. Calculating 3φ Short Circuit MVA with the utility:
Positive sequence impedance diagram for determine the fault current at the bus 1:
Fig. 4.8: Positive Sequence impedance
Diagram at Bus 1
The shtort circuit current from utility:
ISCH = 20,000 A
S SCH = 3(VL − L )( I SCH )
S SCH = 3(38kv)(20, 000 A) = 1316MVA
Finding base current:
SBASE = 5 MVA VBASE = 38 KV
S
I BASE = BASE
3VBASE
5MVA
I BASE = = 76.05 A
3(38kV )
Converting short circuit current in per unit:
I
I pu = real
I BASE
20, 000 A
I pu = = 263 pu
76.05 A
Page 100 of 263

101. Calculating the per unit current to per unit impedance.
1∠0
Z pu = = 3.8022*10−3 pu
263 pu
Simulating a short circuit at secondary side of transformer:
(V ) 2
Z BASE = BASE
S BASE
(38Kv) 2
Z BASE = = 289Ω
5MVA
The base impedance at the other side of the transformer.
(289Ω)
Z BASE = 2
= 3.46Ω
 38kV 
 
 4.16kV 
Calculating the line one impedance in per unit:
Z
Z L1 pu = real
Z BASE
0.00144Ω
Z L1 pu = = 0.416*10−3 pu
3.46Ω
Calculating short circuit current at the bus 1:
4.16
I BASE = (76.05 A)( ) = 698.68 A
0.48
1∠0o
I SCH pu =
ZTH pu
1∠0o
I SCH = = 15.07 pu
(3.8022*10−3 ) pu + (0.0621) pu + (0.416*10−3 ) pu
Changing per unit current to real current:
I SCH p = (15.07 pu )(694.68 A) = 10, 468.83 A
Page 101 of 263

102. Fig. 4.9: Three Phase Fault at Bus 1
Analysis
For the short circuit showed above, the device that operates are the instantaneous (50) and
back-up relay (51). If relay does not operate, fuse 1 will operate likes back up. This
coordination has approximately a 25 cycles different to the other coordination.
Transferring current to the other side of transformer 1:
I SCHprimary
I SCH sec ondary =
a
(10, 468.83)
I SCH sec ondary = = 1,146.06 A
 38 
 
 4.16 
Page 102 of 263

103. Positive sequence impedance diagram for current fault at the bus 2:
Fig. 4.10: Positive Sequence Impedance Diagram at Bus 2
Converting line three impedance to per unit:
0.012Ω
Z L 3 pu = = 0.003468 pu
3.46Ω
Doing a short circuit at the bus 2:
1∠0o
I SCH = = 14.33 pu
(3.8022*10−3 ) pu + (0.0621) pu + (0.416*10−3 ) pu + (0.003468) pu
Changing the current in amperes:
I BASE = 694.68) A
I SCH = (14.33 pu )(694.68 A) = 9,954.76 A
Page 103 of 263

104. ETAP Short circuit results:
Fig. 4.11: Three Phase Fault at Bus 2
Analysis
For this short circuit the device that operates as primary protection is fuse 2. If fuse does
not operate, relay (51) will operate as back up with approximately 25 cycles of different to
the other coordination.
Page 104 of 263

105. Doing a short circuit at load 1:
Positive sequence impedance diagram for current fault at the load 1:
Fig. 4.12: Positive Sequence Impedance Diagram at Load 1
Calculating line five per unit impedance:
0.00027Ω
Z L 5 pu = = 0.078*10 −3 pu
3.46Ω
Changing transformer impedance:
5MVA
Z newT 3 = 0.03 pu ( ) = 0.1 pu
1.5MVA
1∠0o
I SCH = = 5.89 pu
(3.8022*10 ) pu + (0.416*10 ) pu + (0.0621) pu + (0.003468) pu + (0.078*10−3 ) pu + (0.1) pu
−3 −3
Transferring current in secondary side of transformer:
4.16kV
I BASE = (694.68 A)( ) = 6014 A
480
I SCH = (6014 A)(5.89 pu ) = 35, 461.1A
Page 105 of 263

106. ETAP Short Circuits Results:
Fig. 4.13: Three Phase Fault at Load 1
Analysis
A fault at transformer 2 or 3 has a protection in secondary side. Fuse 3 will operates like a
back up with 25 cycles of different between primary protection. If fuse 3 does not operate,
fuse 2 will operate with 25 cycles different between the fuse 3.
Page 106 of 263

107. Doing a short circuit at load five:
Positive sequence impedance diagram for a short circuit current at the load 5:
Fig. 4.14: Positive Impedance Diagram at Load 5
Calculating new impedance of transformer 7:
5MVA
Z newT 7 = 0.025 pu ( ) = 0.833 pu
0.15MVA
Changing line impedance to per unit impedance:
0.0044Ω
Z Line9 = = 0.001272 pu
3.46Ω
1∠0o
I SCH = = 1.11 pu
(3.8022*10−3 ) pu + (0.416*10−3 ) pu + (0.0621) pu + (0.001272) pu + (0.833) pu
The real current in amperes:
I SCH = (1.11 pu )(6020.56) = 6, 682.82 A
Page 107 of 263

108. ETAP Short circuits results:
Fig. 4.15: Three Phase Fault at Load 6
Analysis
Transformer 7 has a protection in the secondary side as a protection to faults as showing
above. Fuse 9 will operates like a back up with 9 cycles of different between primary
protection.
Page 108 of 263

109. Calculating line to ground Short Circuit MVA:
Positive sequence impedance diagram for determine the short circuit curremt at the
bus 1:
Fig. 4.16: Positive Sequence Impedance
Diagram at Bus 1 for a Line to Ground Fault.
ZTH ( + ) = (3.8022*10 −3 + 0.0621 + 0.416 *10−3 ) pu = 0.066318 pu
Cero sequence impedance diagram for determine the short circuit curremt at the bus
1:
Fig. 4.17: Zero Sequence Impedance Diagram at Bus 1
0.000720
Z L1(0) = = 0.208*10−3 pu
3.36
ZTH (0) = (0.208*10−3 + 0.0621) pu = 0.062308 pu
Short circuit at the bus1:
 1∠00 
I0 =  (+) (−) 
 ZTH 2 + ZTH 
 1∠00 
I0 =   = 5.12 pu
 ((0.066318)2 + 0.0837) pu 
I SCH = (5.12 pu )(3) = 15.38
I SCH = (15.38 pu )(694.68 A) = 10, 684.17 A
Page 109 of 263

110. ETAP Short circuits Results:
Fig. 4.18: Line to Ground Fault at Bus 1
Analysis
When a line to ground fault occurs at bus 1 the instantaneous (50N) and back-up relay
(51N) must operate. If they do not operate, then fuse 1 will operate likes back up. This
coordination has approximately a 25 cycles different to other coordination.
Page 110 of 263

111. Short circuit at the bus 2:
Positive sequence impedance diagram for determine the short circuit curremt at the
bus 2:
Fig. 4.19: Positive Sequence Impedance
Diagram at Bus 2 for a Line to Ground Fault.
Z ( + ) = (3.8022*10−3 + 0.0621 + 0.416*10−3 + 0.003468) pu = 0.06978 pu
Cero sequence impedance diagram for determine the short circuit curremt at the bus
2:
Fig. 4.20: Zero Sequence Impedance Diagram
at Bus 2.
0.006
Z L 3(0) = = 0.001734 pu
3.46
Z (0) = (0.208*10−3 + 0.0621 + 0.001734) pu = 0.06404 pu
 1∠00 
I0 =   = 4.9 pu
 (0.06978)2 + 0.06404) pu 
I SCH = (4.9 pu )(3 A) = 14.7 A
I SCH = (14.7 pu )(694.68) = 10, 211.79 A
Page 111 of 263

112. ETAP Short Circuit Results:
Fig. 4.21: Line to Ground Fault at Bus 2.
Analysis
For this short circuit the device that operates as primary protection is fuse 2. If fuse does
not operate, relay (51N) will operate as back up with approximately 25 cycles of diffe
different
to the other coordination.
Page 112 of 263

113. Short circuit at the load 1:
Positive sequence impedance for determine the short circuit current at the load 1:
Fig. 4.22: Positive Sequence
Impedance Diagram at Load 1
for a Line to Ground Fault.
Z ( + ) = (3.8022*10−3 + 0.0621 + 0.416*10−3 + 0.003468 + 0.27 *10−3 + 0.1) pu = 0.17005 pu
Cero sequence impedance for determine the short circuit current at the load 1:
Fig. 4.23: Zero Sequence Impedance Diagram
at Load 1.
0.135*10−3
Z L 5(0) = = 0.039*10−3
3.46
Z (0) = 0.1 pu
The short circuit current:
 1∠00 
I0 =   = 2.27 pu
 (0.17005)2 + 0.1) pu 
I SCH = (2.27 pu )(3) = 6.81 pu
I SCH = (6.81 pu )(6020.56 A) = 41, 039 A
Page 113 of 263

114. ETAP Short Circuits Results:
Fig. 4.24: Line to Ground Fault at Load 1.
Analysis
Transformer 2 has a protection in secondary side. The fuse 3 will operates like a back up
with 25 cycles of different in between primary protection. If fuse 3 does not operate, fuse 2
will operate with 25 cycles different between the fuse 3.
Page 114 of 263

115. Short circuit at the load 5:
Positive sequence impedance for determine the short circuit current at the load 5:
Fig. 4.25: Positive Sequence
Impedance Diagram at
Load 5 for a Line to Ground
Fault.
Z ( + ) = (3.8022*10−3 + 0.0621 + 0.416*10−3 + 0.0044 + 0.833) pu = 0.9037 pu
Cero sequence impedance for determine the short circuit current at the load 5:
0Z Transformer 7
Fig. 4.26: Zero Sequence Impedance Diagram
at Load 5.
Z (0) = 0.833 pu
The short circuit current:
 1∠00 
I0 =   = 0.3787 pu
 (0.9037)2 + 0.833) pu 
I SCH = (0.3787 pu )(3) = 1.13 pu
I SCH = (6020.56)(1.13 pu ) = 6,803.23 A
Page 115 of 263

116. ETAP Short Circuit Results:
Fig. 4.27: Line to Ground Fault. At Load 5
Analysis
Transformer 7 has a protection in the secondary side against line to ground faults. If a fault
of this type happens, fuse 9 will operates like a back up with 9 cycles of different between
primary protection.
Page 116 of 263

117. Calculating 3φ Short Circuit with generators:
Simulating a short circuit at bus 1:
Positive sequence impedance to determine the short circuit current at the generator
bus:
Fig. 4.28: Positive Sequence Impedance
Diagram at Generator Bus.
Finding the new impedance of the generators:
2
V  S 
Z NEW = Z puold  BASEOLD   BASENEW 
 VBASENEW   S BASEOLD 
2
 4.16kV   5MVA  −3
Z NEW = 0.19     = 4.55*10 pu
 38kV   2.5MVA 
Changing the generators impedance to per unit impedance:
0.00285Ω
Z LG1 = Z LG 2 = = 0.824*10−3 pu
3.46Ω
The impedance at the bus 1:
2
 VBASE   S BASENEW 
Z NEW G1 = Z NEW G 2 = Z puold    
 VBASENEW   S BASEOLD 
   
2
 4.16   5MVA  −3
Z NEW G1 = Z NEW G 2 = 0.19    2.5MVA  = 4.55*10 pu
 38   
Z G1+ LG1 // Z G 2+ LG 2
Z G1+ LG1 // Z G 2 + LG 2 = 2.687 *10−3 pu
Calculating the short circuit current:
1∠0 1∠0
I SCH = =
ZTH Z G1+ LG1 // Z G 2 + LG 2
1∠0
I SCH = = 372.16 pu
2.687 *10−3 pu
Changing the per unit current to real current:
I BASE = 694.68 A
I SCH = (372.16 pu )(694.68 A) = 258,532.1A
Page 117 of 263

118. Positive sequence impedance to determine the short circuit current at the bus 2:
Fig. 4.29: Positive Sequence Impedance
Diagram at Bus 2 using Generators.
Doing a short circuit at the bus 2:
1∠0 1∠0
I SCH = =
ZTH Z LG1 // Z LG 2 + Z L 3
1∠0
I SCH = = 162.46 pu
(2.687 *10 + 3.468*10−3 ) pu
−3
Changing the per unit current to real current:
I SCH = (162.46 pu )(694 A) = 112,864.33 A
Page 118 of 263

119. Positive sequence impedance to determine a short circuit current at the load 1:
Fig. 4.30: Positive Sequence Impedance
Diagram at Load 1 using Generators.
Doing a short circuit at the load 1:
1∠0 1∠0
I SCH = =
ZTH Z G1+ LG1 // Z G 2 + LG 2 + Z L 3 + Z L 5 + ZT 2
1∠0
I SCH = = 9.41 pu
(2.687 *10 + 3.468*10−3 + 0.078*10−3 + 0.1) pu
−3
Converting the per unit current to real current:
I BASE = 6020.56 A
I SCH = (9.41 pu )(6020.56 A) = 56, 673.16 A
Page 119 of 263

120. Positive sequence impedance to determine a short circuit current at load 5:
Fig. 4.31: Positive Sequence Impedance
Diagram at Load 5 using Generators.
Doing a short circuit at the secondary size of transformer 7:
1∠0 1∠0
I SCH = =
ZTH Z G1+ LG1 // Z G 2 + LG 2 + Z L 4 + Z L 9 + ZT 7
1∠0
I SCH = −3
= 1.19 pu
(2.687*10 + 0.001272 + 0.833) pu
Changing the per unit current to real current:
I SCH = (1.19 pu )(6020.56 A) = 7,193.37 A
Page 120 of 263

121. Fault line to ground using the generators:
Positive sequence impedance to determine a short circuit current at the generator
bus:
Fig. 4.32: Positive Sequence Impedance
Diagram at Generators Bus for a Line to
Ground Fault.
ZTH + = 2.687 *10 −3 pu
Cero sequence impedance to determine a short circuit current at the generator bus:
Fig. 4.33: Zero Sequence Impedance Diagram
at Generators Bus.
Finding the new impedance of the generators:
2
 VBASEOLD   S BASENEW 
   
0
Z = Z puold
NEW
 VBASE   S BASE 
 NEW   OLD 
2
 4.16kV   5MVA 
Z 0 NEW = 0.05   
−3
 = 1.198*10 pu
 38kV   2.5MVA 
Page 121 of 263

122. The impedance at the bus 1:
0.015Ω
Z 0 LG1 = = 4.34*10 −3 pu
3.45Ω
Z G1+ LG1 = Z 0 G 2+ LG 2 = (1.198*10 −3 + 0.434 *10 −3 ) pu = 1.632*10−3 pu
0
Z 0TH = Z G1+ LG1 // Z G 2+ LG 2 = 0.816 *10−3 pu
Calculating the short circuit current:
1∠0
I0 =
2( Z TH ) + ZTH 0
+
1∠0
I0 = = (161.5 pu )3 = 484.65 pu
 2(2.687 *10 ) + 0.816 *10 −3  pu

−3

Changing the per unit current to real current:
I SCH = (484.65 pu )(694.68 A) = 336, 678.51A
Positive sequence impedance to determine a short circuit current at the bus 2:
Fig. 4.34: Positive Sequence Impedance
Diagram at Bus 2 Using Generators for a Line
to Ground Fault.
Z +TH = Z G1+ LG1 // Z G 2 + LG 2 + Z L 3 + Z L 5 = (2.687 *10−3 + 3.468*10−3 ) pu = 6.155 pu
Page 122 of 263

123. Cero sequence impedance to determine a short circuit current at the bus 2:
Fig. 4.35: Zero Sequence Impedance Diagram
at Bus 2 Using Generators.
Z 0TH = Z G1 // Z G 2 + Z L 3 + Z L 5 = (0.816*10−3 + 1.734 *10 −3 ) pu = 2.55*10 −3 pu
Doing a short circuit at the bus 2:
1∠0
I0 = = 67.29 pu
[ 2(0.006155) + 0.00255] pu
I SCH = (67.29 pu )(3) = 201.88 pu
Changing the per unit current to real current:
I SCH = (201.88 pu )(694.68 A) = 140, 244.95 A
Page 123 of 263

124. Positive sequence impedance to determine a short circuit current at the load 1:
Fig. 4.36: Positive Sequence Impedance
Diagram at Load 1 Using Generators for a
Line to Ground Fault.
ZTH + = (6.155*10−3 + 0.078*10−3 + 0.1) pu = 0.1062 pu
Cero sequence impedance to determine a short circuit current at the load 1:
Fig. 4.37: Zero Sequence Impedance Diagram
at Load 1 Using Generators.
Doing a short circuit at the load 1:
Z 0TH = ZT 2 = 0.1 pu
The short circuit current:
1∠0
I0 = = 3.2 pu
[ 2(0.1062) + 0.1] pu
I SCH = (3.2 pu )(3) = 9.6 pu
Converting the per unit current to real current:
I SCH = (9.6 pu )(6020.56 A) = 57,815.87 A
Page 124 of 263

125. Positive sequence impedance to determine a short circuit current at the load 5:
Fig. 4.38: Positive Sequence Impedance
Diagram at Load 5 Using Generators for a
Line to Ground Fault.
Z + TH = Z G1+ LG1 // Z G 2+ LG 2 + Z L 4 + Z L 9 + Z T 7 = (0.816 *10−3 + 1.272 *10−3 + 0.833) pu = 0.835 pu
Cero sequence impedance to determine a short circuit current at the load 5:
Fig. 4.39: Zero Sequence Impedance Diagram
at Load 5 Using Generators.
Z 0TH = ZT 7 = 0.833 pu
Doing a short circuit at the secondary side of the transformer 7:
1∠0
I0 = = 0.39 pu
[ 2(0.835) + 0.833] pu
I SCH = (0.39 pu )(3) = 1.19 pu
Changing the per unit current to real current:
I SCH = (1.19 pu )(6020.56 A) = 7,164.46 A
Page 125 of 263

126. Selecting the fuses:
Fuse at transformer 3:
Using the slow speed curve
1) Step 1: Nominal Current
1.5MVA
I No min al = = 208.4 A
3(38kV )
F ≥ 300 E
2) Step2: Inrush current
I Inrush = (208.42)(12) = 2,501A @ 6 cycles
F ≥ 300 E These fuses hold 9,546 A.
3) Step 3: Short circuit current
I SCH = 4, 090 A Looking in the graph total clearing time.
The fuse opens at 0.396s or 23.76 cycles.
Fuse at the bus 3:
Using the Time-delayed fuse
1) Step 1: Nominal current
3MVA
I No min al = = 416 A
3(4.16kV )
F ≥ 600
2) Step 2: Inrush current
I Inrush = (208)(12) + 208 = 2, 704 A @ 6 cycles
F ≥ 600 These fuse hold 7,037 A at 6 cycles.
3) Step 3: Short circuit current
I SCH = 9,950 A
Using the graph total clearing time the fuse will open at 0.027s or 1.62 cycles.
Page 126 of 263

127. The fuses at the transformer number 7.
Using the standard speed curve
1) Step 1: Nominal current
0.15MVA
I No min al = = 20.8 A
3(4.16kV )
F ≥ 30 E
2) Step 2: Inrush current
I Inrush = (20.8)(12) = 250 A @ 6 cycles
F ≥ 30 E These fuse hold 1,015 A at 6 cycles.
3) Step 3: Short circuit current
I SCH = 772 A
Finding the graph total clearing time the fuse will open at 0.133s or 7.98 cycles.
Fuse at the Utility:
Using the very slow speed curve
1) Step 1: Nominal current
5MVA
I No min al = = 75.97 A
3(38kV )
F ≥ 100
2) Step 2: Inrush current
I Inrush = (76)(12) = 912 A @ 6 cycles
F ≥ 100 These fuse hold 3,754 A at 6 cycles.
3) Step 3: Short circuit current
I SCH = 20, 000 A
Finding the graph total clearing time the fuse will open at 0.025s or 1.5 cycles.
Page 127 of 263

128. Calculating Relays:
Selecting the CTR for the transformers:
a) The CTR has to comply with all the methods:
I N = 695 A
 695 A 
CTR ≥ 1.2  
 5 
1200  695 A 
≥ 1.2  
5  5 
240 ≥ 167
The CTR complied with the equation.
I SC
b) ≤ 100 A
CTR
3, 460
≤ 100 A
240
14.4 ≤ 100A
The ratio between the short circuit and the CTR complied with the requirement.
CTRvoltage
c) Burden( z ) =
20 I N
1200
Burden( z ) = = 0.086Ω
20(695 A)
The burden could not exceed 0.086Ω.
Page 128 of 263

129. Selecting the CTR for the generators:
a) I N = 695 A
 695 A 
CTR ≥ 1.2  
 5 
7000  695 A 
≥ 1.2  
5  5 
1400 ≥ 167
The CTR complied with the equation.
I SC
b) ≤ 100 A
CTR
133, 248 A
≤ 100 A
7, 000
5
95 ≤ 100A
The ratio between the short circuit and the CTR complied with the requirement.
CTRvoltage
c) Burden( z ) =
20 I N
7, 000
Burden( z ) = = 0.5Ω
20(695 A)
The Burden could not exceed 0.5Ω.
Page 129 of 263

130. Equation Curve:
Relay 351A: Three phase fault at the bus 1 using utility:
Setting Overcurrent Relay:
Element 50
I SCH = 10,104 A
The multiple to use in the ETAP Program:
I
M = SCH
CTR
10,104 A
M= = 42.1 Instantaneous operation time
1, 200
5
Element 51
Pick − up = 1.2 I FL
Pick − up = 1.2(695 A) = 834 A Aproximated in ETAP program 816A .
I SCH
M=
Pick − up
9, 950
M= = 12.19
816
Time Operation Equation
TPRELAY = 0.344 s
 5.67 
TPR ELAY = TD 0.0352 + 2 
 M −1
 5.67 
0.344 = TD 0.0352 + 
 12.192 − 1 
TD = 4.67 Using the Extremely Inverse Curve
Page 130 of 263

131. Line to ground fault at the bus 1 using utility:
Setting for Overcurrent Relay.
Element 50N
I SCH = 10,104 A
Multiple used in the ETAP program.
I
M = SCH
CTR
10,104 A
M= = 42.1
1, 200
5
Instantaneous operation time
Element 51N
I SCH = 10, 729 A
834 A
Pick − up = 1.2(695 A) = = 278 A
3
The multiple used in the ETAP program. The multiple used in the
curves.
I I SCH
M = SCH M=
CTR Pick − up
278 A 10, 729
M= = 1.15 steps = 0.01 M= = 37.25
1200 288
5
Operation Time Equation:
TPRELAY = 0.335s
 5.67 
TPR ELAY = TD 0.0352 + 2 
 M −1
 5.67 
0.335 = TD 0.0352 + 
 37.252 − 1 
TD = 8.53 Using the Extremely Inverse Curve
Page 131 of 263

132. Generation Operation Overcurrent Relay:
Relay 300G: Three phase fault at the bus G using generators:
Primary protection
3φ Short circuit at the bus of the each generator:
258,532.1A
I SCH = = 129, 266.05 A
2
The multiple to be used the relay curve.
129, 266.05
M= = 310.10
416.84
Element 51
The pick-up current for the relay.
I FL = 347.37 A
Pick − up = 1.2 I FL
Pick − up = 1.2(347.37 A) = 416.84 A
Finding the operation time relay.
 5.67 
TPR ELAY = TD 0.0352 + 2 
 M −1
 5.67 
TPR ELAY = 8.48 0.0352 +  = 0.298s
 310.10 2 − 1 
TPR ELAY = 0.298s Using extremely inverse curve.
Page 132 of 263

133. Element 50
Multiple used in ETAP program.
100, 000
M= = 71.42
7, 000
5
Element 51N
The pick-up current for the relay.
I FL = 347.37 A
1.2 I FL
Pick − up =
3
1.2(347.37 A)
Pick − up = = 130.95 A
3
Short circuit Line to ground at the bus of the generator:
336, 678.51A
I SCH = = 168,339.25 A
2
Finding the multiple to be used in the ETAP program:
168, 339.25
M= = 1, 285.52
130.95
Finding operation time relay.
TD = 8.52
 5.67 
TPR ELAY = 8.52 0.0352 + 2  = 0.299 s
 1, 285.52 − 1 
TPR ELAY = 0.299 s Using extremely inverse curve
Element 50N
The multiple used in ETAP program.
I SCH = 200, 000 A
200, 000
M= = 142.85
7, 000
5
Page 133 of 263

134. Generator Relay working as backup protection.
Doing a 3φ Fault at the bus 2:
Element 51
The pick-up current for the relay.
Pick − up = 416.84 A
The short circuit current of each generator.
112,864.3
I SCH = = 54, 432.15
2
The multiple to be used in the Relay curve.
54, 432.15
M= = 135.38
416.84
Finding the operation time relay.
 5.67 
TPR ELAY = TD 0.0352 + 2 
 M −1
 5.67 
TPR ELAY = 8.48 0.0352 +  = 0.29 s
 135.382 − 1 
TPR ELAY = 0.29 s Using extremely inverse curve
Page 134 of 263

135. Doing a Line to ground fault at the bus 2:
Element 51N
The pick-up current for the relay.
416.84 A
Pick − up = = 138.94 A
3
The schort circuit current .
140, 244.95 A
I SCH = = 70,122.47 A
2
The multiple to be used in the Relay curve.
70,122.47
M= = 504.67
138.94
Finding the operation time relay.
 5.67 
TPR ELAY = TD 0.0352 + 2 
 M −1
 5.67 
TPR ELAY = 8.52 0.0352 +  = 0.30 s
 504.67 2 − 1 
TPR ELAY = 0.30 s Using extremely inverse curve
Page 135 of 263

136. Doing a 3φ Fault at the load 1:
Element 51
Short circuit current at load 1.
I SCH = 56, 673.16 A
Transferring short circuit current to generators side.
56, 673.16 A
I SCH = = 6,539.21A
4.16
0.48
Current contribution of each generator.
6, 539.21A
I SCH = = 3, 296.6 A
2
The pick-up current for the relay.
Pick − up = 416.84 A
Multiple to be used in Relay curve.
3, 296.6
M= = 7.84
416.84
Finding operation time relay.
 5.67 
TPR ELAY = TD 0.0352 + 2 
 M −1
 5.67 
TPR ELAY = 8.48 0.0352 +  = 1.093s
 7.842 − 1 
TPR ELAY = 1.093s Using extremely inverse curve
Page 136 of 263

137. Doing a Line to ground fault at the load 1:
Element 51N
The pick-up current for the relay.
416.84 A
Pick − up = = 138.94 A
3
The short circuit current .
57,815.87 A
I SCH = = 6, 671.06 A
4.16
0.48
The short circuit current of each generator.
6, 671.06
I SCH = = 3,335.53 A
2
The multiple to be used in the Relay curve.
3, 335.53
M= = 24
138.94
Finding the operation time relay.
 5.67 
TPR ELAY = TD 0.0352 + 2 
 M −1
 5.67 
TPR ELAY = 8.52 0.0352 + 2  = 0.38s
 24 − 1 
TPR ELAY = 0.38s Using extremely inverse curve
Page 137 of 263

138. 4.5 Short Circuit Study
Page 138 of 263

139. Short Circuit Study
A. Single Line Short circuit SM Report - Short Circuit Study for the Power
Transformers T1, T2, T3, T4, T5, T6 and T7.
The section VI. A. contains the ETAP computer program output single line short
circuit cases and SM reports, detailing the short circuit current available in each
distribution voltage buses.
The following table contains the power transformer characteristics and short circuit
summary.
# Power Transformers
T1 T2 T3 T4 T5 T6 T7
Characteristics
1 Voltage in kV 38/4.16 4.16/0.48 4.16/0.48 38/4.16 4.16/0.48 4.16/0.48 4.16/0.48
2 Capacity in MVA 5 1.5 1.5 5 1.5 1.5 0.15
3 Impedance in % 6.21 3 3 6.21 3 3 2.5
4 Connection D-Y D-Y D-Y D-Y D-Y D-Y D-Y
Secondary Winding Short
5 Circuit Three Phase Current 20,000 4,090 4,090 20,000 4,090 4,090 772
(A) at High Side
Secondary Winding Short
6 Circuit Three Phase Current 10,520 35,440 35,440 10,520 35,440 35,440 6,690
(A) at Low Side
Secondary Winding Short
7 Circuit Line to Ground 0 0 0 0 0 0 0
Current (A) at High Side
Secondary Winding Short
8 Circuit Line to Ground 10,730 41,060 41,060 10,730 41,060 41,060 6,850
Current (A) at Low Side
Each simulation page includes the incoming short circuit current magnitude from the 38 kV
PREPA’S electric power system (20000 amps for three phase and 11547 amps for phase to
ground) and the secondary current at distribution voltage busses at Bayamón Waste Water
Treatment Plant.
Page 139 of 263

140. 4.5.1: Three phase fault at utility
Fig. 4.40: Fault Simulation at Primary Side of
38KV/4.16KV Utility Transformer of BWWTP
*Note: The presented fault is the same at T4 primary side.
Page 140 of 263

141. Fig. 4.41: Sequence of Operations Events at
Primary Side of T1.
When a three phase fault arise at primary side of 38KV/4.16KV transformer (T1)
the fuse 1 will operate at 1.50 cycles (24.9ms) as shown above.
Page 141 of 263

142. Project: Protective Device Coordination ETAP Page: 1
5.5.0C
Location: WWTP, Bayamon Date: 04-16-2007
Contract: SN: BETA-ELECT
Engineer: Hector, Jose, Daniel Revision: Base
Study Case: SM
Filename: JHD-CS Config.: Normal
SHORT- CIRCUIT REPORT
Fault at bus: BTP-2
Prefault voltage = 38.000 kV = 100.00 % of nominal bus kV ( 38.000 kV)
= 100.00 % of base kV ( 38.000 kV)
Positive & Zero Sequence Impedances
Contribution 3-Phase Fault Line-To-Ground Fault Looking into "From Bus"
From Bus To Bus %V kA % Voltage at From Bus kA Symm. rms % Impedance on 100 MVA base
ID ID From Bus Symm. rms Va Vb Vc Ia 3I0 R1 X1 R0 X0
BTP-2 Total 0.00 20.000 0.00 173.21 173.21 0.000 0.000 3.79E-001 7.59E+000
BTS-2 BTP-2 0.00 0.000 100.00 100.00 100.00 0.000 0.000
Utility 1 BTP-2 100.00 20.000 0.00 173.21 173.21 0.000 0.000 3.79E-001 7.59E+000
Bus-1 BTS-2 0.00 0.000 100.00 100.00 100.00 0.000 0.000
Bus-2 Bus-1 0.00 0.000 100.00 100.00 100.00 0.000 0.000
Bus-1 Bus7 0.00 0.000 100.00 100.00 100.00 0.000 0.000
# Indicates fault current contribution is from three-winding transformers
* Indicates a zero sequence fault current contribution (3I0) from a grounded Delta-Y transformer
Page 142 of 263

143. Analysis
When the system has a Three Phase Fault the impedance view is only the utility impedance.
The impedance is founded by Puerto Rico Electric Authority (PREPA). We can find the
short circuit current in the line asking to PREPA which is the short circuit current at that
point of the system. However when the system occur a Line to Ground Fault the
transformers configuration is Delta at the primary winding and the circuit impedance is
open by the configuration. For these reason the short circuit current is zero amperes.
Page 143 of 263

144. 4.5.2: Three phase fault at bus 1
Fig. 4.42: Fault Simulation at Bus 1 of
BWWTP
*Note: The presented fault is the same at bus 6.
Page 144 of 263

145. Fig. 4.43: Sequence of Operation Events at Bus 1
Analysis
For the short circuit showed above, the device that operates are the instantaneous (50) and
back-up relay (51). If relay does not operate, fuse 1 will operate likes back up. This
coordination has approximately a 25 cycles different to the other coordination.
Page 145 of 263

146. Project: Protective Device Coordination ETAP Page: 1
5.5.0C
Location: WWTP, Bayamon Date: 04-16-2007
Contract: SN: BETA-ELECT
Engineer: Hector, Jose, Daniel Revision: Base
Study Case: SM
Filename: JHD-CS Config.: Normal
SHORT- CIRCUIT REPORT
Fault at bus: Bus-1
Prefault voltage = 4.160 kV = 100.00 % of nominal bus kV ( 4.160 kV)
= 100.00 % of base kV ( 4.160 kV)
Positive & Zero Sequence Impedances
Contribution 3-Phase Fault Line-To-Ground Fault Looking into "From Bus"
From Bus To Bus %V kA % Voltage at From Bus kA Symm. rms % Impedance on 100 MVA base
ID ID From Bus Symm. rms Va Vb Vc Ia 3I0 R1 X1 R0 X0
Bus-1 Total 0.00 10.522 0.00 98.93 99.13 10.729 10.729 1.07E+001 1.31E+002 1.05E+001 1.24E+002
BTS-2 Bus-1 0.10 10.522 0.14 98.98 99.09 10.729 10.729 1.07E+001 1.31E+002 1.05E+001 1.24E+002
Bus-2 Bus-1 0.00 0.000 0.00 98.93 99.13 0.000 0.000
BTP-2 BTS-2 94.24 10.522 97.02 100.00 97.14 10.729 10.729 * 1.06E+001 1.31E+002 1.02E+001 1.24E+002
BTP-4 Bus-2 0.00 0.000 0.00 98.93 99.13 0.000 0.000
BTP-6 Bus-2 0.00 0.000 0.00 98.93 99.13 0.000 0.000
Utility 1 BTP-2 100.00 1.152 100.00 100.00 100.00 0.678 0.000 3.79E-001 7.59E+000
BTS-4 BTP-4 0.00 0.000 57.23 57.12 100.00 0.000 0.000
BTS-6 BTP-6 0.00 0.000 57.23 57.12 100.00 0.000 0.000
Bus-1 Bus7 0.00 0.000 0.00 98.93 99.13 0.000 0.000
# Indicates fault current contribution is from three-winding transformers
* Indicates a zero sequence fault current contribution (3I0) from a grounded Delta-Y transformer
Page 146 of 263

147. Analysis
For this system occurred a Three Phase Fault at the bus-1. The systems see the utility
impedance, the transformer impedance and the line impedance. For this fault the short
circuit is 10,522 A at the bus-1. However when the system occur a Line to Ground Fault we
have to consider the zero sequence impedance. The connection for the transformer 1 is
Delta-Wye. For this configuration we have to open the second winding at the primary side.
The zero sequence is diagram is open by the configuration. For these reason the short
circuit current is 10,729 A at the bus-1.
Page 147 of 263

148. 4.5.3: Three phase fault at the bus 2
Fig. 4.44: Fault Simulation at Bus 2 of
BWWTP
*Note: The presented fault is the same at bus 3.
Page 148 of 263

149. Fig. 4.45: Sequence of Operation Events at Bus 2
Analysis
For this short circuit the device that operates as primary protection is fuse 2. If fuse does
not operate, relay (51) will operate as back up with approximately 25 cycles of different to
the other coordination.
Page 149 of 263

150. Project: Protective Device Coordination ETAP Page: 1
5.5.0C
Location: WWTP, Bayamon Date: 04-16-2007
Contract: SN: BETA-ELECT
Engineer: Hector, Jose, Daniel Revision: Base
Study Case: SM
Filename: JHD-CS Config.: Normal
SHORT- CIRCUIT REPORT
Fault at bus: Bus-2
Prefault voltage = 4.160 kV = 100.00 % of nominal bus kV ( 4.160 kV)
= 100.00 % of base kV ( 4.160 kV)
Positive & Zero Sequence Impedances
Contribution 3-Phase Fault Line-To-Ground Fault Looking into "From Bus"
From Bus To Bus %V kA % Voltage at From Bus kA Symm. rms % Impedance on 100 MVA base
ID ID From Bus Symm. rms Va Vb Vc Ia 3I0 R1 X1 R0 X0
Bus-2 Total 0.00 9.954 0.00 95.69 102.22 10.176 10.176 1.68E+001 1.38E+002 3.05E+001 1.27E+002
Bus-1 Bus-2 6.65 9.954 8.97 98.87 99.31 10.176 10.176 1.68E+001 1.38E+002 3.05E+001 1.27E+002
BTP-4 Bus-2 0.00 0.000 0.00 95.69 102.22 0.000 0.000
BTP-6 Bus-2 0.00 0.000 0.00 95.69 102.22 0.000 0.000
BTS-2 Bus-1 6.75 9.954 9.10 98.92 99.26 10.176 10.176 1.07E+001 1.31E+002 1.05E+001 1.24E+002
BTS-4 BTP-4 0.00 0.000 59.02 55.25 100.00 0.000 0.000
BTS-6 BTP-6 0.00 0.000 59.02 55.25 100.00 0.000 0.000
BTP-2 BTS-2 94.57 9.954 97.07 100.00 97.42 10.176 10.176 * 1.06E+001 1.31E+002 1.02E+001 1.24E+002
Bus-1 Bus7 6.65 0.000 8.97 98.87 99.31 0.000 0.000
# Indicates fault current contribution is from three-winding transformers
* Indicates a zero sequence fault current contribution (3I0) from a grounded Delta-Y transformer
Page 150 of 263

151. Analysis
The Three Phase failure that occurred at the bus-2 is adding the line impedance three. The
short circuit current is 9.954A. When we compare the short circuit at the bus-1 is less
because the impedance magnitude has changed. For a Line to Ground Fault the system have
the same change in the zero sequence impedance. The systems consider the zero sequence
impedance at the line three at this fault. The short circuit current is 10,176 A at the bus-2.
Page 151 of 263

152. 4.5.4: Three phase fault at load 1
Fig. 4.46: Fault Simulation at Load 1 of
BWWTP
*Note: The presented fault is the same at the Loads 2, 4, 5.
Page 152 of 263

153. Fig. 4.47: Sequence of Operations Events at
Load 1
Analysis
A fault at transformer 2 or 3 has a protection in secondary side. Fuse 3 will operates like a
back up with 25 cycles of different between primary protection. If fuse 3 does not operate,
fuse 2 will operate with 25 cycles different between the fuse 3.
Page 153 of 263

154. Project: Protective Device Coordination ETAP Page: 1
5.5.0C
Location: WWTP, Bayamon Date: 04-16-2007
Contract: SN: BETA-ELECT
Engineer: Hector, Jose, Daniel Revision: Base
Study Case: SM
Filename: JHD-CS Config.: Normal
SHORT- CIRCUIT REPORT
Fault at bus: BTS-4
Prefault voltage = 0.480 kV = 100.00 % of nominal bus kV ( 0.480 kV)
= 100.00 % of base kV ( 0.480 kV)
Positive & Zero Sequence Impedances
Contribution 3-Phase Fault Line-To-Ground Fault Looking into "From Bus"
From Bus To Bus %V kA % Voltage at From Bus kA Symm. rms % Impedance on 100 MVA base
ID ID From Bus Symm. rms Va Vb Vc Ia 3I0 R1 X1 R0 X0
BTS-4 Total 0.00 35.438 0.00 92.90 93.28 41.060 41.060 4.47E+001 3.36E+002 2.79E+001 1.98E+002
BTP-4 BTS-4 58.93 35.438 77.20 100.00 77.66 41.060 41.060 * 4.47E+001 3.36E+002 2.79E+001 1.98E+002
Bus-2 BTP-4 58.93 4.089 77.20 100.00 77.66 2.735 0.000 1.79E+002 7.10E+001
Bus-1 Bus-2 61.22 4.089 77.73 100.00 79.48 2.735 0.000 1.79E+002 7.10E+001
BTP-6 Bus-2 58.93 0.000 77.20 100.00 77.66 0.000 0.000
Bus-1 Bus7 61.22 0.000 77.73 100.00 79.48 0.000 0.000
# Indicates fault current contribution is from three-winding transformers
* Indicates a zero sequence fault current contribution (3I0) from a grounded Delta-Y transformer
Page 154 of 263

155. Analysis
A Three Phase Fault is happened in the secondary side of the transformer 7 (BTS-12). The
transformer capacity is 0.15 MVA and the connection is Delta-Wye. The impedance
viewed at this point is by the utility, two transformers and lines. The short circuit current is
6,687A. When the Line to Ground Fault occur the zero sequence impedance is open by the
primary side of the transformer 7 (BTS-12). The short circuit current at the secondary side
of the transformer is 6,855A.
Page 155 of 263

156. 4.5.5: Three phase fault at Load 6
Fig. 4.48: Fault Simulation at Load 6 of
BWWTP
Page 156 of 263

157. Fig. 4.49: Sequence of Operation Events at
Load 6
Analysis
Transformer 7 has a protection in the secondary side as a protection to faults as showing
above. Fuse 9 will operates like a back up with 9 cycles of different between primary
protection.
Page 157 of 263

158. Project: Protective Device Coordination ETAP Page: 1
5.5.0C
Location: WWTP, Bayamon Date: 04-16-2007
Contract: SN: BETA-ELECT
Engineer: Hector, Jose, Daniel Revision: Base
Study Case: SM
Filename: JHD-CS Config.: Normal
SHORT- CIRCUIT REPORT
Fault at bus: BTS-12
Prefault voltage = 0.480 kV = 100.00 % of nominal bus kV ( 0.480 kV)
= 100.00 % of base kV ( 0.480 kV)
Positive & Zero Sequence Impedances
Contribution 3-Phase Fault Line-To-Ground Fault Looking into "From Bus"
From Bus To Bus %V kA % Voltage at From Bus kA Symm. rms % Impedance on 100 MVA base
ID ID From Bus Symm. rms Va Vb Vc Ia 3I0 R1 X1 R0 X0
BTS-12 Total 0.00 6.687 0.00 98.84 98.70 6.855 6.855 9.45E+001 1.80E+003 8.32E+001 1.66E+003
BTP-12 BTS-12 92.65 6.687 96.34 100.00 96.18 6.855 6.855 * 9.45E+001 1.80E+003 8.32E+001 1.66E+003
Bus6 BTP-12 92.67 0.772 96.33 100.00 96.20 0.457 0.000 8.97E+002 1.56E+002
BTS-3 Bus6 92.68 0.772 96.34 100.00 96.21 0.457 0.000 8.96E+002 1.56E+002
Bus-3 Bus6 92.67 0.000 96.33 100.00 96.20 0.000 0.000
Bus10 Bus6 92.67 0.000 96.33 100.00 96.20 0.000 0.000
# Indicates fault current contribution is from three-winding transformers
* Indicates a zero sequence fault current contribution (3I0) from a grounded Delta-Y transformer
Page 158 of 263

159. Analysis
A Three Phase Fault is happened in the secondary side of the transformer 7 (BTS-12). The
transformer capacity is 0.15 MVA and the connection is Delta-Wye. The impedance
viewed at this point is by the utility, two transformers and lines. The short circuit current is
6,687A. When the Line to Ground Fault occur the zero sequence impedance is open by the
primary side of the transformer 7 (BTS-12). The short circuit current at the secondary side
of the transformer is 6,855A.
Page 159 of 263

160. 4.6 Power Fuses Selection for
Power Transformers T1, T2,
T3, T4, T5, T6 and T7
Page 160 of 263

161. V. Protective Device Selection
A. Power Fuses Selection
Power Transformers T1, T2, T3, T4, T5, T6 and T7
The Power Fuse Time Coordination show the analysis for the short circuit
simulations at the utility side and the power plant side for the T1, T2, T3, T4, T5,
T6 and T7.
The fuse coordination complies with time (12-30cycles) permitted by each
coordination.
The following table shows the power fuse summary for the transformers.
# Power Transformer Recommended Power Fuse Curve
1 T1 38/4.16 SMD-2C-100E Slow Speed
2 T2 4.16/0.48 SMU-40-300E Slow Speed
3 T3 4.16/0.48 SMU-40-300E Slow Speed
4 T4 38/4.16 SMD-2C-100E Slow Speed
5 T5 4.16/0.48 SMU-40-300E Slow Speed
6 T6 4.16/0.48 SMU-40-300E Slow Speed
7 T7 4.16/0.48 SMU-40-30E STD Speed
8 Main Feeder Fault Fiter-600 Time-delayed
Fig. 4.50: Recommendations to Fuse Protection
*Note: The fuse curves are in the appendix.
Page 161 of 263

162. Treatment power Plant
Power Transformer 1-2 Time Fuse Coordination
Project: Bayamón Waste Water Treatment Plant
Voltage (kV): 38/4.16
Connection (Type): DELTA-WYE
Capacity (MVA): 5
Impedance (Z%): 6.21 @ 5 MVA
IFL (Amps High Side): 76.05 @ 5 MVA IINRUSH CURRENT = (IFL *12): 912.16
ISC (AEE): 20,000
Fig. 4.51: Time Fuse 1 and 5 Coordination
Page 162 of 263

163. Fig. 4.52: Characteristics Curves for Fuse 1 and 5
The fuse chosen has the capacity to break the short circuit at 0.475 A or 28.5 cycles.
Page 163 of 263

164. S&C SMD-2C
The next figures show the operation of different fuses by ours recommendation and
alternatives options. The fuses are operating like a back up protection to accomplish to our
protection criteria.
Curve Fuse 65E 80E 100E 125E 150E
STD Speed
Minimum 4.39 9.28 10.92 18.06 27.00
Melting Time
Total clearing 8.52 11.58 16.50 24.78 36.06
Time
Curve Fuse 65E 80E 100E 125E 150E
Slow Speed
Minimum 7.02 12.12 20.58 33.30 51.48
Melting Time
Total clearing 11.70 17.82 28.32 44.28 67.32
Time
Curve Fuse
Recommended Slow Speed 100 E
Fuse Fig. 4.53: Fuse 1 and 5 recommended
Alternative STD Speed 125 E
Fuse
Page 164 of 263

165. Treatment power Plant
Main Feeder Time Fuse Coordination
Project: Power Treatment Plant
Voltage (kV): 4.16
IFL (Amps High Side): 416.85
Fig. 4.54: Time Fuse 2 and 6 Coordination
Page 165 of 263

166. Fig. 4.55: Characteristics Curves for fuse 2 and 6
The fuse chosen has the capacity to break the arch at 0.84s or 50.4 cycles.
Fault Fiter
The fault fiter fuse has the same curves for the other fusible. That makes the option to select
the best operation time in the case that has to operate the fuse
Curve Fuse 400 600
Time Delayed
Minimum 22.62 43.8
Melting Time
Total clearing 26.34 50.4
Time
Fig. 4.56: Fuse 2 and 6 Recommended
Page 166 of 263

167. Treatment power Plant
Power Transformer 2-3, 5-6 Time Fuse Coordination
Project: Power Treatment Plant
Voltage (kV): 4.16/0.48
Connection (Type): DELTA-WYE
Capacity (MVA): 1.5
Impedance (Z%): 3 @ 1.5 MVA
IFL (Amps High Side): 208.45 @ 1.5 MVA IINRUSH CURRENT = (IFL *12): 2,501.45
Fig. 4.57: Time Fuse 3, 4, 7 and 8 Coordination
Page 167 of 263

168. Fig. 4.58: Characteristics Curves for fuses 3, 4, 7 and 8
The fuse selected has the capacity to break the arch at 0.395s or 23.7 cycles.
Page 168 of 263

169. S&C SMU-40
The next figures show the operation of different fuses by ours recommendation and
alternatives options. The fuses are operating like a back up protection to accomplish to our
protection criteria.
Curve Fuse 200E 250E 300E 400E
STD Speed
Minimum 3.27 4.65 7.14 11.76
Melting Time
Total clearing 7.20 8.88 14.28 20.22
Time
Curve Fuse 200E 250E 300E 400E
Slow Speed
Minimum 6.72 10.20 14.94 24.96
Melting Time
Total clearing 11.40 15.54 23.76 33.36
Time
Curve Fuse
Recommended Slow Speed 300 E
Fuse
Alternative STD Speed 400 E Fig. 4.59: Fuse 3, 4, 7 and 8 Recommended
Fuse
Page 169 of 263

170. Treatment power Plant
Power Transformer 7 Time Fuse Coordination
Project: Power Treatment Plant
Voltage (kV): 4.16/0.48
Connection (Type): DELTA-WYE
Capacity(MVA): 0.15
Impedance (Z%): 2,5 @ 0.15 MVA
IFL (Amps High Side): 20.84 @ 1.5 MVA IINRUSH CURRENT = (IFL *12): 250.11
Fig. 4.60: Time Fuse 9 Coordination
Page 170 of 263

171. Fig. 4.61: Characteristics Curves for fuse 9
The fuse chosen has the capacity to break the short circuit at 0.155s or 9.30 cycles.
Page 171 of 263

172. S&C SMU-40
The next figures show the operation of different fuses by ours recommendation and
alternatives options. The fuses are operating like a back up protection to accomplish to our
protection criteria.
Curve Fuse 20E 25E 30E 40E 50E
STD Speed
Minimum 1.08 1.75 2.15 3.53 5.27
Melting Time
Total clearing 6.66 7.50 7.98 9.66 11.76
Time
Curve Fuse 20E 25E 30E 40E 50E
Slow Speed
Minimum 1.40 1.86 3.24 6.66 10.80
Melting Time
Total clearing 7.08 7.62 9.30 13.44 18.40
Time
Curve Fuse
Recommended Slow Speed 30 E
Fuse Fig. 4.60: Fuse 9 Recommended
Alternative STD Speed 40 E
Fuse
Page 172 of 263

173. 4.7 Protection Relay
Settings for
Distribution Feeders
Page 173 of 263

174. Page 174 of 263

175. Page 175 of 263

176. Page 176 of 263

177. Page 177 of 263

178. 4.8 Relay Settings
Page 178 of 263

179. Relay 351A:
Relay 351A
Operation Protection Devices
Element Pick-up Extremely Inverse Curve
M TD
51 816 A 12.19 4.67
50 10,104 A X X
Extremely Inverse Curve
51N 278 A 37.25 8.53
50N 10,104 A X X
Directional Power Relay
Pick-up (pu) Time
32 0.57 0.5
Fig. 4.63: Relay 351A Settings
After finish all necessary calculations by hand to reach al requirements of
coordination using 23 to 25 cycles between coordinaion levels we found setings
specifications for Relay 351A. These setting are shown above. The coordination was
performed with ETAP software.
Relay 351A is used for protect transformer 1 an 2. The elements in the relay are 50,
51, 50N, 51N, 32.
Page 179 of 263

180. Relay 300G:
Relay 300G
Operation Protection Devices
Element Pick-up Extremely Inverse Curve
M TD
51 416.84 A 188.47 8.48
50 80,000 A X X
Extremely Inverse Curve
51N 138.95 A 565.39 8.52
50N 80,000 A X X
Fig. 4.64: Overcurent Relay Settings for Generator
Relay 300G
Operation Protection Devices
Element Voltage
Under voltage Overvoltage
27/59 4,160 V 4,035 V 4,285 V
Frequency Relay
Frequency Over Frequency Under Frequency
81 60 Hz 61.2 Hz 58.8 Hz
Fig. 4.65: Undervoltage, Overvoltage, Frequency
of Power Relay for Generator
Relay 300G is used to protect generator. The relay components are overcurrent
protection (50, 51, 50N, 51N), overvoltage (59) and underoltage (27), frequency protection
(81). After finish calculations with necessary coordination levels and criteria we select the
settings presented in tables above.
Page 180 of 263

181. 4.9 Results
Page 181 of 263

182. Results
We realized a three phase fault through BWWTP power system using PREPA
connection. Our evaluation criteria to all faults were 23 to 25 cycles of difference between
coordination levels. Figure 4.60 shows the short circuits magnitudes at the points analyzed.
It also includes operation time for each equipment.
Page 182 of 263

183. Fault using the utility:
Three Phase Fault
Operating Short
Localization
Voltage Circuit Operation Protection Devices Time (Cycles)
Fault
(kV) Current
Fuse1/5 Fuse2/6 Fuse3/4/7/8 Fuse9 Relay(50) Relay(51)
T1, T4 Primary 38 20,000A 1.44 -------- -------- -------- -------- --------
T1, T4
4.16 10,504 A 44.70 -------- -------- -------- -------- --------
Secondary
Bus1, Bus 6 4.16 10,500 A 44.82 -------- -------- -------- 0 19.5
Bus2, Bus 3 4.16 9,950 A 49.62 1.62 -------- -------- -------- 23.64
T2, T3, T5, T6
4.16 9,950 A -------- 1.62 5.88 -------- -------- 23.64
Primary
T2, T3, T5, T6
0.48 35,440 A -------- 50.4 23.76 -------- -------- 75.78
Secondary
T7 Primary 4.16 9,950 A 49.62 1.62 -------- -------- -------- 23.64
T7 Secondary 0.48 6,690 A -------- -------- -------- 7.98 -------- --------
Fig. 4.66: Three Phase Fault Results
Page 183 of 263

184. The figure below shows line to ground fault at different areas of system. This kind of fault
change operation time of devices. However, protective device coordination still working
the same. All points reach coordination criteria of 23 to 25 cycles between coordination
levels. Results was verified with manual calculations and using ETAP software.
Line to ground Fault
Operating Short
Localization
Voltage Circuit Operation Protection Devices Time (Cycles)
Fault
(kV) Current
Fuse 1/5 Fuse 2/6 Fuse 3/4/7/8 Fuse 9 Relay(50) Relay(51)
T1, T4 Primary 38 0A -------- -------- -------- -------- -------- --------
T1, T4
4.16 0A -------- -------- -------- -------- -------- --------
Secondary
Bus1, Bus 6 4.16 10,730 A -------- -------- -------- -------- 0 23.10
Bus2, Bus 3 4.16 10,180 A -------- 1.62 -------- -------- 0 23.10
T2, T3, T5, T6
4.16 10,180 A -------- 1.62 5.7 -------- -------- 23.10
Primary
T2, T3, T5, T6
0.48 41,060 A -------- -------- 48.78 -------- -------- --------
Secondary
T7 Primary 4.16 10,730 A -------- -------- -------- -------- 0 23.10
T7 Secondary 0.48 6,850 A -------- -------- -------- 14.34 -------- --------
Fig. 4.67: Line to Ground Fault Results
Page 184 of 263

185. When Bayamón WWTP is working with generators is possible that faults could
happen. For that reason we made protective device coordination for BWWTP using
generators. For a three phase fault at generators the overcurrent relay operates. If a fault
occurs in system far from generators, protective devices work faster than when using
utility. It reduces time between coordination devices. Coordination results are showing in
table below.
Fault using the generators:
Three Phase Fault
Operated
Localization Short Circuit
Voltage Operation Protection Devices Time (Cycles)
Fault Current
(kV)
Fuse Fuse Fuse
Fuse 9 RelayG(50) RelayG(51)
1/5 2/6 3/4/7/8
Bus1, Bus 6 4.16 258,532.1 A -------- -------- -------- 0 0 17.91
Bus2, Bus 3 4.16 112,864.33 A -------- 0 -------- -------- -------- 18.06
T2, T3, T5, T6
0.48 56,673.16 A -------- 0.78 5.4 -------- -------- 65.58
Secondary
T7 Secondary 0.48 7,193.37 A -------- -------- -------- 1.8 -------- --------
Fig. 4.68: Three Phase Fault Results Using
Generators.
Line to ground Fault
Localization Operated Short Circuit
Fault Voltage Current Operation Protection Devices Time (Cycles)
(kV)
Fuse 1/5 Fuse 2/6 Fuse Fuse 9 Relay(50) Relay(51)
3/4/7/8
336,678,51 A -------- -------- -------- 0 0 18.0
Bus1, Bus 6 4.16
140,244.95 A -------- 0 -------- -------- -------- 18.0
Bus2, Bus 3 4.16
T2, T3, T5, T6 57,815.87 A -------- 33.6 5.58 -------- -------- 33.6
0.48
Secondary
T7 Secondary 7,164.46 A -------- -------- -------- 1.8 -------- --------
0.48
Fig. 4.69: Line to Ground Fault Results Using
Generators
Page 185 of 263

186. Chapter 5: Protective Device
Coordination Project Results
Page 186 of 263

187. Contents
Alternatives Considered…………………………………………………………………. 188
System Specification…………………………………………………………………….. 190
Magazine Article………………………………………………………………………… 195
Budget…………………………………………………………………………………… 196
Bibliography……………………………………………………………………………... 197
Conclusions……………………………………………………………………………… 199
Page 187 of 263

188. 5.1 Alternatives Considered
Through the capstone project appears many questions with multiple solutions. That
moved us to realize brainstorming to find the best way of action. We analyzed each
possible solution as a great alternative and visualized their advantages and disadvantages.
Then, we chose the best answer. There is a summary of alternatives considered.
I. Protective Devices
There are a lot of protective devices at market today. It gives us many alternatives
to considered. However, to choose a protective device, first we have to look system
capacity, localization and kind of charge connected to it.
II. Manufacturer Selection
Every manufacturer offers different protective devices to perform the same thing in
a power system. For that reason we have a lot of alternatives about which protective
device should be used. Each device does not work at same way. According to this, we
prefer to use most commonly used manufacturers and devices in Puerto Rico.
III. Compatibility of Devices
As part of protective device coordination each protective device has to work as a
team with other devices. But, unfortunately, some devices are not compatible with
devices produced by others manufacturers. It force us to considerate the alternative of
use devices of same manufacturer of existing devices in power system. If we do not
considered this alternative, protective device coordination will not be complete.
IV. Fault Analysis
There are many things that could make a system fault. In field of power system,
these faults are classified in four categories. These are: phase to phase, single phase to
ground, double phase to ground and, three phase fault. A fault can occur everywhere at
any time. Also, is possible that occur more than once at in power system at the same
Page 188 of 263

189. time. Is very important remember this detail. If we do it, then we could realize a better
contingency, which means best protective device coordination.
In our design the short circuit study give us the information to select the appropriate
protective devices. With the faults magnitude in the different parts of the system our
devices operates with our coordination criteria (23 to 25 cycles) and protect the
equipments of damage.
V. User Guide:
a. One user guide.
The option of write only one user guide was very tempting. It
represents less work for us. But, write one manual with an explanation of all
elements in program, data required, and possible mistakes made by user,
could make it too long. A long user guide can make that people do not want
to read it. Also, we thought in busy engineers who do not have time to read
a long manual. They need something short and easy to read. For that reason
we discard the idea.
b. Two user guides.
We realized the idea of create two user guides, basic one and advance
one. The basic user guide has the purpose of give an explanation step by
step of how to use ETAP program. It covers from how to build a one-line
diagram to how to perform a short circuit analysis. Also, this guide is
written to be easy to read and understand. Busy engineers can perform a
power system simulation fast and without problem.
At this time, we thought that some people may ask for more
information. For them, we prepared a second user guide, an advance user
guide. In this guide we give more specific details of some features of ETAP
program. For example, we include a case study solution as a model of how
made a simulation with program. Also, it includes equipment data
requirements, and technical terms uses by ETAP software.
Page 189 of 263

190. We chosen this second alternative, because we understand it is more
practical for today’s engineers.
Page 190 of 263

191. 5.2 System Specifications
Circuit Breaker
A circuit breaker is an automatically-operated electrical switch designed to protect
an electrical circuit from damage caused by overload or short circuit. Unlike a fuse, which
operates once and then has to be replaced, a circuit breaker can be reset (either manually or
automatically) to resume normal operation. Circuit breakers are made in varying sizes, from
small devices that protect an individual household appliance up to large switchgear
designed to protect high voltage circuits feeding an entire city.
Fig. 5.1: Vacuum Circuit Breaker
Fuse
In electronics and electrical engineering a fuse, short for 'fusible link', is a type of
overcurrent protection device. Its essential component is a metal wire or strip that melts
when too much current flows. When the metal strip melts, it opens the circuit of which it's a
part, and so protects the circuit from excessive current.
A practical fuse was one of the essential features of Edison's electrical power distribution
system. An early fuse was said to have successfully protected an Edison installation from
tampering by a rival gas-lighting concern.
Fuses (and other overcurrent devices) are an essential part of a power distribution system to
prevent fire or damage. When too much current flows through a wire, it may overheat and
be damaged or even start a fire. Wiring regulations give the maximum rating of a fuse for
protection of a particular circuit. Local authorities will incorporate national wiring
Page 191 of 263

192. regulations as part of law. Fuses are selected to allow passage of normal currents, but to
quickly interrupt a short circuit or overload condition.
Fig. 5.2: Power Fuse
Relay
A relay is an electrical switch that opens and closes under the control of another
electrical circuit. In the original form, the switch is operated by an electromagnet to open or
close one or many sets of contacts. It was invented by Joseph Henry in 1835. Because a
relay is able to control an output circuit of higher power than the input circuit, it can be
considered to be, in a broad sense, a form of an electrical amplifier.
Fig. 5.3: Protective Relay
Page 192 of 263

193. Operation
When a current flows through the coil, the resulting magnetic field attracts an
armature that is mechanically linked to a moving contact. The movement either makes or
breaks a connection with a fixed contact. When the current to the coil is switched off, the
armature is returned by a force approximately half as strong as the magnetic force to its
relaxed position. Usually this is a spring, but gravity is also used commonly in industrial
motor starters. Most relays are manufactured to operate quickly. In a low voltage
application, this is to reduce noise. In a high voltage or high current application, this is to
reduce arcing.
If the coil is energized with DC, a diode is frequently installed across the coil, to
dissipate the energy from the collapsing magnetic field at deactivation, which would
otherwise generate a spike of voltage and might cause damage to circuit components. Some
automotive relays already include that diode inside the relay case. Alternatively a contact
protection network, consisting of a capacitor and resistor in series, may absorb the surge. If
the coil is designed to be energized with AC, a small copper ring can be crimped to the end
of the solenoid. This "shading ring" creates a small out-of-phase current, which increases
the minimum pull on the armature during the AC cycle.
By analogy with the functions of the original electromagnetic device, a solid-state
relay is made with a thyristor or other solid-state switching device. To achieve electrical
isolation an optocoupler can be used which is a light-emitting diode (LED) coupled with a
photo transistor.
Protective relay
A protective relay is a complex electromechanical apparatus, often with more than
one coil, designed to calculate operating conditions on an electrical circuit and trip circuit
breakers when a fault was found. Unlike switching type relays with fixed and usually ill-
defined operating voltage thresholds and operating times, protective relays had well-
established, selectable, time/current (or other operating parameter) curves. Such relays were
very elaborate, using arrays of induction disks, shaded-pole magnets, operating and
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194. restraint coils, solenoid-type operators, telephone-relay style contacts, and phase-shifting
networks to allow the relay to respond to such conditions as over-current, over-voltage,
reverse power flow, over- and under- frequency, and even distance relays that would trip
for faults up to a certain distance away from a substation but not beyond that point. An
important transmission line or generator unit would have had cubicles dedicated to
protection, with a score of individual electromechanical devices. The various protective
functions available on a given relay are denoted by standard ANSI Device Numbers. For
example, a relay including function 51 would be a timed overcurrent protective relay.
These protective relays provide various types of electrical protection by detecting
abnormal conditions and isolating them from the rest of the electrical system by circuit
breaker operation. Such relays may be located at the service entrance or at major load
centers.
Design and theory of these protective devices is an important part of the education
of an electrical engineer who specializes in power systems. Today these devices are nearly
entirely replaced (in new designs) with microprocessor-based instruments (numerical
relays) that emulate their electromechanical ancestors with great precision and convenience
in application. By combining several functions in one case, numerical relays also save
capital cost and maintenance cost over electromechanical relays. However, due to their very
long life span, tens of thousands of these "silent sentinels" are still protecting transmission
lines and electrical apparatus all over the world.
Overcurrent relay
An "Overcurrent Relay" is a type of protective relay which operates when the load
current exceeds a preset value. The ANSI Device Designation Number is 50 for an
Instantaneous OverCurrent (IOC), 51 for a Time OverCurrent (TOC). In a typical
application the overcurrent relay is used for overcurrent protection, connected to a current
transformer and calibrated to operate at or above a specific current level. When the relay
Page 194 of 263

195. operates, one or more contacts will operate and energize a trip coil in a Circuit Breaker and
trip (open) the Circuit Breaker.
Distance relay
It is a protective relay used to protect power transmission and distribution lines
against different fault types. The relay monitors line impedance by measuring line voltage
and current. Once a fault occurs, the voltage drops to zero and thus the measured
impedance become less than the setting value ``reach``. As a result the relay issues a trip
command.
Transformer
A transformer is a device that transfers electrical energy from one circuit to
another through inductively coupled wires. A changing current in the first circuit (the
primary) creates a changing magnetic field; in turn, this magnetic field induces a changing
voltage in the second circuit (the secondary). By adding a load to the secondary circuit, one
can make current flow in the transformer, thus transferring energy from one circuit to the
other.
The secondary induced voltage VS is scaled from the primary VP by a factor ideally
equal to the ratio of the number of turns of wire in their respective windings:
By appropriate selection of the numbers of turns, a transformer thus allows an alternating
voltage to be stepped up — by making NS more than NP — or stepped down, by making it
less.
A key application of transformers is to reduce the current before transmitting
electrical energy over long distances through wires. Most wires have resistance and so
dissipate electrical energy at a rate proportional to the square of the current through the
wire. By transforming electrical power to a high-voltage, and therefore low-current form
for transmission and back again afterwards, transformers enable the economic transmission
Page 195 of 263

196. of power over long distances. Consequently, transformers have shaped the electricity
supply industry, permitting generation to be located remotely from points of demand. All
but a fraction of the world's electrical power has passed through a series of transformers by
the time it reaches the consumer.
Transformers are some of the most efficient electrical 'machines', with some large units
able to transfer 99.75% of their input power to their output. Transformers come in a range
of sizes from a thumbnail-sized coupling transformer hidden inside a stage microphone to
huge units weighing hundreds of tones used to interconnect portions of national power
grids. All operate with the same basic principles, though a variety of designs exist to
perform specialized roles throughout home and industry.
ETAP Software
This software is designed to perform power system simulations. It is a very advance
program capable to simulate most of power system analysis. Unfortunately, it is a little
hard to understand. To run the software you need at least 1 Mb RAM processor with
Windows XP or higher.
Page 196 of 263

197. Magazine Article
Page 197 of 263

198. 5.4 Budget
Table A. Materials required developing the data base
Amount Description Price p/u Total
1 Laptop $800.00 $800.00
1 ETAP software $4000.00 $4000.00
1 Logbook $23.00 $23.00
Total $4823.00
Table B. Professional Service Cost
Job Title Number of Salary per Weekly Monthly 6 Month
Employers Hour Hours Hours Salary
Research &
Development 3 $15.00 15 60 $16,200
Team
Page 198 of 263

199. 5.5 Bibliography
• Power System Protection, [Online]. Available:
http://en.wikipedia.org/wiki/Protection_and_monitoring_of_the_electrical_energy_t
ransmission_networks
• Electrical Engineering History, [Online]. Available:
http://www.history.com/encyclopedia.do?articleId=208367
• Electricity, [Online]. Available:
http://www.eia.doe.gov/kids/history/timelines/electricity.html
• Short Circuit Analysis, [Online]. Available: http://www.answers.com/topic/short-
circuit?cat=technology
• General Electric: (www.ge.com/products_services/electrical_distribution.html).
• ABB: (http://www.abb.com/ProductGuide/Alphabetical.aspx)
• Cutler Hammer:
(http://www.eaton.com/EatonCom/Markets/Electrical/Products/SwitchingDevicesan
dDisconnects/EnclosedCircuitBreakers/index.htm)
• Siemens: (http://w1.siemens.com/en/us/entry.html)
• Square D:
(http://www.squared.com/us/squared/corporate_info.nsf/unid/ECA90110AB7098C
A85256A3A007091D7/$file/productsa2zFrameset.htm)
• ETAP Program, [Online] Available: www.etap.com
• International Electric Power Encyclopedia, 1998 Per Wel, Publishing Company,
Tulas, UK.
• International Electric Power Encyclopedia, 1999 Per Wel, Publishing Company,
Tulas, UK.
• Zaberszky, John; Rittenhouse, Joseph W.; Electric Power Transmission, The Ronald
Press Company, 1954.
• T. Davies C., Protection of Industrial Power Systems; Pergamon Press, 1984.
• Duncan Glober, J.; Sarma Mulukutla; Power System Analysis and Design; PWS-
KENT Publishing Company, Boston.
• Anderson, P.M.; Power System Protection; McGraw Hill, 1998.
Page 199 of 263

200. • Circuit Breakers, suitehged, substations and fuses, Ed. 1995; IEEE standards
Collection.
Page 200 of 263

201. 5.6 Conclusion
In this project we work with computer software, called ETAP, to analyze the
protection coordination of an electrical design. We started analyzing and searching
information about how to use the program. We prepared two User guides to help in the use
and comprehension of the program. Our purpose was preparing something easy for reading
and understanding. When the user guide was complete, we make an example design and
utilize the program to corroborate the protective device coordination of the power system.
In the final part, we analyzed a new design, a real develop. All the coordination of the
system was make manually and in the ETAP program.
Page 201 of 263

202. Chapter 6: Administrative Section
Page 202 of 263

203. Contents
Protective Device Coordination Project Proposal……………………………………….. 203
Capstone Design 1 Proposal Presentation….…………………………………………..... 214
Progress Report………………………………………………………………………….. 220
Work Schedule…………………………………………………………………………... 239
Page 203 of 263

204. Table of Figures
Fig. 6.1: Protective Devices……………………………………………………………... 213
Fig. 6.2: Budget to Complete Design…………………………………………………… 218
Fig. 6.3: Salary Cap……………………………………………………………………... 218
Page 204 of 263

205. 6.1 Protective Device
Coordination Project
Proposal
Page 205 of 263

206. POYTECHNIC UNIVERSITY OF PUERTO RICO
ELECTRICAL ENGINEERING DEPARTMENT
HATO REY, PUERTO RICO
CAPSTONE DESIGN COURSE 1
EE 5002 - 22
PROF. ASDRUBAL MORALES COLÓN
PROPOSAL
PROTECTIVE DEVICE COORDINATION
GROUP 28
Laporte Plaza, Daniel J. 0108949
Pagán Hernández, José A. A0000002020
Rivera Alejandro, Héctor J. 0109470
SEPTEMBER 25, 2007
Page 206 of 263

207. Problem Definition
The power protection analysis is one of the main criteria’s in the electrical design. Different
kinds of programs have been created to analyze the coordination of protection in electrical
systems. Some of protection programs do not provide a database with sufficient
information about relays and others protection equipments.
In our project we will work to improve the database of an existent program. Searching
information about different power relays, fuses and other protection mechanism we will
work to analyze the behavior of these and improve the database of the program. The
equipments utilized in electric system are very expensive. The electrical systems must be
very reliable and the protection of these is one of the principle fields in electrical
engineering. Our projects talks about different topics in electrical engineering like
protection coordination, database for programs, power engineering, power relays,
protection equipment and others fields in power.
Page 207 of 263

208. Introduction
Electricity has been a subject of scientific interest since at least the early 17th century.
Probably the first electrical engineer was William Gilbert who designed the versorium: a
device that detected the presence of statically charged objects. He was also the first to draw
a clear distinction between magnetism and static electricity and is credited with establishing
the term electricity. However it was not until the 19th century that research into the subject
started to intensify. Notable developments in this century include the work of Georg Ohm,
who in 1827 quantified the relationship between the electric current and potential difference
in a conductor, Michael Faraday, the discoverer of electromagnetic induction in 1831, and
James Clerk Maxwell, who in 1873 published a unified theory of electricity and magnetism
in his treatise on Electricity and Magnetism. They are the fathers of electrical engineering
and the electric systems.
Today, power system protection is that part of electrical power engineering that deals with
protecting the electrical power system from faults by isolating the faulted part from the rest
of the network.
Any electric-distribution system involves a large amount of supplementary equipment for
the protection of generators, transformers, and the transmission lines. Circuit breakers are
employed to protect all elements of a power system from short circuits and overloads, and
for normal switching operations.
The principle of a protection scheme is to keep the power system stable by isolating only
the components that are under fault, even as leaving as much of the network as possible still
in operation. Thus, protection schemes must apply a very pragmatic and pessimistic
approach to clearing system faults. For this reason, the technology and philosophies utilized
in protection schemes are often old and well-established because they must be very reliable.
In much the same way as the early computers of the 1950s and 1960s were a precursor to
the computational capabilities of today’s computers. Specialized hardwire systems were
developed for locally monitoring the operation of power plants and for remotely monitoring
and controlling switches in transmission substation. The Remote Terminal Units of these
early monitoring systems were implemented with relay logic, while the master station
consisted primarily of large banks of annunciator panels with red and green light indication
Page 208 of 263

209. the state of the points being monitored with flashing light indication a change in state or an
alarm condition.
The impact of computers has nowhere been more revolutionary than in electrical
engineering. The design, analysis and operation of electrical and electronic systems has
become completely dominated by computers, a transformation that has been motivated by
the natural ease of interface between computers and electrical systems, and the promise of
spectacular improvements in speed and efficiency.
Our project consists of develop a protective device coordination using a graphical software
program to add features and flexibility in the area of electrical system protection. Also, this
graphical software program it’s going to be using for all kind of element that used these.
We will select the software program, analyze all types of element protection that are
utilizing in electrical systems, and simulate the program using various management studies.
Page 209 of 263

210. Objectives
• To make a research about technical references of fuses, relays and breakers.
• Understand technical data format of protection devices.
• To learn how to use the protective device coordination program.
• Create the database of a graphical software program.
• Build a library to graphical system to represent every fuses, relay and breaker.
• Perform a case study with the improved software program.
• Establish the system coordination of a case study with the improved program.
Page 210 of 263

211. Constraints
• Ways to use library of ETAP program. Start by understanding.
• How to create the monolineal diagram of the design in this program.
• Method on building the protection diagram of it design.
• Understand how to work a short circuit test in the program.
• Interpret results in the program to establish the coordination of a protection system.
• Run the program with all kind of requisites.
Page 211 of 263

212. Expected Results
• Find the technical data of relays, fuses and breakers.
• Understand clearly the operation of the protection devices.
• Domain the use program to perform analyze of the system.
• Create a set of easy drawings to selection with the system protection symbols.
• Improve the graphic system with the greatest quantity of protective equipment.
• Develop a case study with the program completely improved.
• Expand database to allow user realize a simulation with the most parts of the
equipment available in market.
• Prepare the protection coordination of an electric design and test it, in the program.
Page 212 of 263

213. Procedure
1. Search information about relays.
2. Make a research of breakers.
3. Find information about fuses.
4. Understand most of concepts of power system protection.
5. Learn how to perform a short circuit analysis.
6. Create a suppliers list.
7. Understand technical data format of the operation mechanism of relays.
8. Comprehend operation mechanism of breakers.
9. Know how work fuses.
10. Obtain program to work with the protection systems.
11. Learn how to use the program.
12. Discover the way to create a database.
13. Develop a database with the available information.
14. Create a library with the graphic system of protection equipment.
15. Perform the mathematic justification of a case study.
16. Make a drawing of an electrical design.
17. Perform a short circuit analysis with the computer program.
18. Realize the protection coordination justification of the design.
19. Create protection coordination with the computer program.
20. Prepare tables of coordinate studies.
Page 213 of 263

214. Design Specifications
Improve an existing power system program to make these most efficient. The work will
consist in develop the database of the program and establish protection coordination of any
scheme protection. In addition, it will include a created electrical design to make a short
circuit test to prove it.
Relay Hardware
The relay hardware for electronic relays consists of both analog and digital devices. The
input signals are analog and require, at very minimum, a conversion to digital form.
Therefore, the relays design is often a mixture of analog electronic devices and digital
hardware. The relays may also contain transformers or other components that are also
found in electromagnetic and electromechanical protective devices.
Induction relays are available in many variations to provide accurate pickup and time-
current responses for a wide range of simple or complex system conditions. Induction
relays are basically induction motors. The moving element, or rotor, is usually a metal disk,
although it sometimes may be a metal cylinder or cup. Electronic relays require less power
to operate than their mechanical equivalents, producing a smaller load burden on the CT’s
and PT’s that supply them. The most frequently used relay is the over current relay,
combining both instantaneous and inverse-time tripping functions.
Page 214 of 263

215. Over current Relays
Fig. 6.1: Protective Devices
Protective Devices
The protective system device usually consists of several elements that are arranged to test
the system condition, make decision regarding the normally of observed variables, and take
action as required. Over current time unit have characteristics such that its operation time
vary inversely with the current flow in the relay. These characteristics are available
generally in three types of curves, Inverse, Very Inverse, and Extremely Inverse.
Other protective device is fuses. Fuses are designed for many different applications and
with variety of characteristics to meet the requirements both routine and special situations.
Fuses have different curves to realize these requirements. The minimum melting curve is an
average melting time measured in low voltage test where arcing does not occur. Other
curve is total clearing curve should be used in coordinating against the minimum melting
characteristics of a larger fuse, located toward the power source. Distribution fuses links are
given voltage ratings of 7.2, 14.4, and 17 KV nominal, or 7.8, 15, and 18 KV maximum for
use in open-link cutouts.
Page 215 of 263

216. Computer Engineering
The Power-flow computer program is the basic tool for investigating power system
operation requirement. Power-flow programs compute the voltage magnitudes, phase
angles, and transmission- line power flows for a network under steady-state operating
conditions. The computers have sufficient networks for more than 200 buses and 2500
transmission lines. Short circuit programs are used to compute three-phase and line-to-
ground faults in power- systems network in order to select circuit breakers for fault
interruption, select relays that detect faults and control circuit breakers and determine the
relay settings. Short-circuit currents are computed for each relay and circuit breaker
location, and for various system-operation conditions such as lines or generating units out
of service, in order to determine minimum and maximum fault currents.
ETAP Program
ETAP seamlessly integrates the analysis of power control circuits within one electrical
analysis program. The control system diagram simulates the sequence of the operation
control devices such as solenoids, relays, controlled contacts multi-sequence contacts and
actuators including inrush conditions. The control system diagram has the capability of
determine pick-up and dropout voltage, losses and current flows at any time instance as
well as overall margin and critical alerts. A large library of equipment enables engineers to
quickly model and simulate the action of relays associate with the control interlocks after
given time delays.
Page 216 of 263

217. Work Schedule
Page 217 of 263

218. Page 218 of 263

219. Page 219 of 263

220. Budget
Table A. Materials required developing the data base
Amount Description Price p/u Total
1 Laptop $800.00 $800.00
1 ETAP software $4000.00 $4000.00
1 Logbook $23.00 $23.00
Total $4823.00
Fig. 6.2: Budget to Complete Design
Table B. Professional Service Cost
Job Title Number of Salary per Weekly Monthly 6 Month
Employers Hour Hours Hours Salary
Research &
Development 3 $15.00 15 60 $16,200
Team
Fig. 6.3: Salary Cap
Page 220 of 263

221. References
• [Online]. Available:
http://en.wikipedia.org/wiki/Protection_and_monitoring_of_the_electrical_energy_t
ransmission_networks
• [Online]. Available: http://www.history.com/encyclopedia.do?articleId=208367
• [Online]. Available:
http://www.eia.doe.gov/kids/history/timelines/electricity.html
• [Online]. Available: http://www.answers.com/topic/short-circuit?cat=technology
• General Electric: (www.ge.com/products_services/electrical_distribution.html).
• ABB: (http://www.abb.com/ProductGuide/Alphabetical.aspx)
• Cutler Hammer:
(http://www.eaton.com/EatonCom/Markets/Electrical/Products/SwitchingDevicesan
dDisconnects/EnclosedCircuitBreakers/index.htm)
• Siemens: (http://w1.siemens.com/en/us/entry.html)
• Square D:
(http://www.squared.com/us/squared/corporate_info.nsf/unid/ECA90110AB7098C
A85256A3A007091D7/$file/productsa2zFrameset.htm)
Page 221 of 263

222. Progress Report
Page 222 of 263

223. Page 223 of 263

224. Page 224 of 263

225. Page 225 of 263

226. Page 226 of 263

227. Page 227 of 263

228. Page 228 of 263

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230. Page 230 of 263

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234. Page 234 of 263

235. Page 235 of 263

236. Page 236 of 263

237. Page 237 of 263

238. Page 238 of 263

239. Page 239 of 263

240. Page 240 of 263

241. Work Schedule
Page 241 of 263

242. Page 242 of 263

243. Page 243 of 263

244. Page 244 of 263

245. Page 245 of 263

246. Appendix
Page 246 of 263

247. Tables and Curves
Page 247 of 263

248. Fig. A.1: NEC Fuse Table
Our design was performed considering NEC requirements.
Page 248 of 263

249. Relays Setting Calculations:
Multiple Curve:
Fig. A.2: Relay Extremely Inverse Curve
Page 249 of 263

250. Fig. A.3: Relay 300G Curves
Page 250 of 263

251. Fig. A.4: Connection Diagrams
Page 251 of 263

252. Protection Relay Settings for
Generators
Page 252 of 263

253. VII. Protection Relay Settings for the Generators
The generator relay coordination and setting were selected following the IEEE Tutorial on
the Protection of Synchronous Generators. The selected relay settings are for the generator
capacity available for the loads.
For the maximum three phase fault cases the coordination relay setting selected is
approximated 24 cycles as a backup protection. Also there is an instantaneous overcurrent
protection adjusted to the maximum short circuit available at the generators bus. For a
ground fault the coordination relays has the approximated 24 cycles between as a backup
protection. The instantaneous over current protection adjusted to the maximum short circuit
at the generator bus.
Protective Relay settings for generators
1. Generator 1
2. Generator 2
Page 253 of 263

254. IEEE Tutorial on the Protection of Synchronous Generators
Abstracting is permitted with credit to the source. For copying, reprint, or republication
permission, write to the IEEE Copyright Manager, IEEE Operation Center, 445 Hoes Lane,
Piscataway, NJ 08855-1331. All rights reserved. Copyright 1995 by The Institute of
Electrical and Electronics Engineers, Inc.
First Printing July 1995
Second Printing October 1995
Third Printing July 1997
Fourth Printing August 1999
IEEE Catalog Number: 95TP102
Additional copies of this publication are available from
IEE Operations Center
P. O. Box 1331
455 Hoes Lane
Piscataway, NJ 08855-1331 USA
1-800-701-IEEE
1-732-981-0060
1-732-981-9667 (FAX)
Email: customer.service@ieee.org
Page 254 of 263

255. A.3 General Information
Page 255 of 263

256. Fault Fiter Electronic Power Fuses:
Fault Fiter® Electronic Power Fuses are a major advancement in
circuit-interruption technology. They integrate state-of-the-art electronics with
an advanced-design high-continuous-current fuse. The electronics provide
current sensing, time-current characteristics, and control power. No remote
relaying or external power is required. Fault Fiter provides unsurpassed high-
speed interruption of fault currents to 40,000 amperes RMS symmetrical. Fault
Fiters are maintenance-free, maintenance-proof.
Fault Fiter Electronic Power Fuses offer superior coordination with source-side
overcurrent relays and load-side feeder fuses. They offer unmatched high-speed circuit-
interrupting performance without producing excessive voltage surges, and they respond
more quickly to high-current faults than conventional fuses. They're ideal for:
• Service-entrance protection and coordination,
• Transformer protection
• Overdutied device protection.
Fuse Protection
Fig. A.7: Fault Fiter Fuse
Page 256 of 263

257. SMU-40 300E, 30E and SMD-2C 100E
Fuses Specifications:
In accordance with procedures described in ANSI Standard C37.41-1981, minimum
melting time-current characteristic curves for S&C power fuses are based on tests starting
at no initial load. When in service, of course, every fuse will be carrying a load that may
approach or even exceed the ampere rating. This preloading reduces the heat-dissipating
ability of the fusible element, and hence reduces its melting time. This effect has been
minimized in S&C power fuses by designing their fusible elements to melt at current levels
not less than 200% of rating.
Fig. A.8: Fuse Units
Page 257 of 263

258. Fault Interruption — SM-20, SML-20, and SMU-40 Power Fuses
Fast, positive fault interruption is achieved in the SMU Fuse Unit through high-speed
elongation of the arc in the solid-material-lined bore, and by the efficient deionizing action
of gases generated through thermal reaction of the solid material due to the heat of the
confined arc. Here's how it works:
• Overcurrent melts the silver fusible element. The strain wire severs, initiating
arcing.
• Released force of drive spring accelerates arcing rod upward, causing rapid
elongation of the arc in the solids-material-lined bore.
Under maximum fault conditions, heat from confined arc causes solid material
in the large-diameter lower section of the arc-extinguishing chamber to undergo
thermal reaction, generating turbulent gases and effectively enlarging the bore
diameter so that the arc energy is released with a mild exhaust.
Under low-to-moderate fault conditions, arc is extinguished in small-diameter
up-per section of the arc-extinguishing chamber, where deionizing gases are
effectively concentrated for efficient arc extinction.
• Continued upper travel of the arcing rod after arc extinction causes actuating pin
to penetrate the upper seal, resulting in projection of the brilliant-red blown-fuse
target from the upper end fitting.
Fig. A.9: SMU-40 Fuse
Page 258 of 263

259. SMD-2C
Fig. A.10: SMD-2C Fuse Units
Fig. A.11: SMD-2C Fuse
Page 259 of 263

260. Protection for Small- and Medium-Sized
Generator Machines
Applications: Fig. A.12: SEL 300G
• Connect the SEL-300G Relay across large generators for complete primary and
backup protection. Adding the neutral voltage connection provides 100 percent
stator ground protection for most machines, based on third-harmonic voltage
measurements. Connecting the neutral current input provides protection for solidly
grounded or resistance grounded machines.
• Apply sensitive percentage-restrained current differential elements and an
unrestrained element, along with synchronism check and volts-per-hertz elements,
across the entire unit to protect both the generator and the step-up transformer.
• Replace auxiliary meters at the generating station by taking advantage of accurate
internal metering.
• Monitor and record generator utilization with internal hour meters that record
stopped time, and full load hours.
Connecting Diagram
Fig. A.13: SEL 300G Installation
Page 260 of 263

261. SEL-351A
Fig. A.14: SEL 351A
The SEL-351A includes a robust set of phase, negative sequence, residual, and neutral
overcurrent elements. Each element type has six levels of instantaneous protection (four of
these levels have definite-time functions). The relay provides directional control for each of
these overcurrent elements.
Overcurrent Elements for Phase Fault Detection
Phase and negative-sequence overcurrent elements detect phase faults. Negative sequence
current elements ignore three-phase load to provide more sensitive coverage of phase-to-
phase faults. Phase overcurrent elements detect three-phase faults that do not have
significant negativesequence quantities.
Directional Protection for Various System
Grounding Practices
Current channel IN, ordered with the optional 0.2 A secondary nominal rating, provides
directional ground protection for the following systems:
• Ungrounded systems
• High-impedance grounded systems
• Petersen Coil grounded systems
• Low-impedance grounded systems
Under- and Overfrequency Protection
Six levels of secure under- (81U) or overfrequency (81O) elements detect true frequency
disturbances. Use the independently time-delayed output of these elements to shed load or
trip local generation. Phase undervoltage supervision prevents undesired frequency element
operation during faults.
Page 261 of 263

262. Functional Overview
Fig. A.15: SEL 351A Overview
Page 262 of 263

263. ABB vacuum circuit breakers
Ratings
ADVAC is available in the full range of ANSI ratings through
15 kV, with interrupting ratings to 1000 MVA and continuous currents through 3000 A
(self-cooled). The ADVAC series of vacuum circuit breakers is a complete line of ANSI-
rated circuit breakers offering power distribution system customers the advantages of the
latest vacuum circuit breaker technology.
Operating
Mechanism
ADVAC uses a simple, front-accessible stored-energy operating mechanism designed
specifically for use with vacuum technology. This provides the benefits of dependable
vacuum interrupters with advanced contact design and proven reliability, without the
complexity of mechanisms and linkages found in previous generation circuit breakers.
Ratings
The switchgear shall be rated at (4.76, 8.25, 15) kV maximum continuous voltage, (250,
350, 500, 750, 1000) MVA nominal interrupting capacity, and (1200, 2000, 3000) amps
continuous current, as shown in the “Rating Structure” table (page 40), with required and
related capabilities in accordance with referenced ANSI standards.
Fig. A.16: ABB Vacuum Circuit Breaker
Page 263 of 263