for my collage work .I need this.

1. SILIGURI INSTITUTE OF TECHNOLOGY
DEPARTMENT OF ELECTRICAL ENGINEERING
SILIGURI - 734009
REPORT
Fault Analysis of Power System
By
Name :Arico Dhar
Roll no. :11901620004
Course title :Power System II
Course Code :PC-EE-601

2. Acknowledgement
I would like to express my gratitude and appreciation to all those who gave me the possibility to complete this report. I would like to convey my
heartfelt gratitude to Mr. Pralay Roy for his tremendous direction and assistance in the completion of my report on the topic ““Fault analysis of
power system”. I got to learn a lot more about this topic which will be very helpful for me. In the end, I would like to thank my parents. Without
them, I would not have been able to complete this project.
Thanking you,
NAME-Arico Dhar
Roll No.- 11901620004

3. Abstract
The fault analysis of a power system is needed in order to provide information for the choice of switch-gear,
size of conductors, setting of relays, finding the rating requirements of other power equipment and
confirming system stability. All the equipment must be chosen to work with the fault current that sometimes
flows in great quantity.

4. Table of Contents
• INTRODUCTION
• TYPES OF FAULT IN POWER SYSTEM
Open circuit fault
Short circuit fault
Asymmetrical fault
Symmetrical fault
• CAUSES OF FAULTS
• CONCLUSION
• REFERENCE

5. Introduction
Fault analysis is an essential tool for the determination of short-circuit currents that result from
different fault phenomena, the estimation of fault locations, the identification of under-rated equipment
in electric power systems and the sizing of various system components including Distributed
Generation components

6. Types of Faults in Power System
The faults in the power system are mainly categorized into two types:
1. Open Circuit Fault
2. Short Circuit Fault

7. Open Circuit Fault:
• The open circuit fault happens due to the failure of one or two conductors. These faults take
place in series with the line so referred as series fault. Such types of faults have a strong
impact on the reliability of the system. The open circuit fault is classified as:
• Open Conductor Fault
• Two conductors Open Fault
• Three conductors Open Fault

8. Short Circuit Fault:
The short-circuit fault is commonly divided into symmetrical and asymmetrical types. These
faults are further categorized as one of five types. In order of frequency of occurrence, they are:
Asymmetrical Faults:
• Asymmetrical faults mandate the calculation of positive negative and zero sequence components
separately.
• Single Line to Ground Fault: This type of fault occurs when you have one of the phases (A, B or C) is
shorted with the ground.
• Line to Line Fault: This type of fault occurs when you have one of the phases (A, B or C) is shorted with
the ground.
• Double Line to Ground Fault: This type of fault occurs when two phases are shorted with the ground
together (A-B-G, B-C-G or C-A-G)

9. Symmetrical Faults:
• Symmetrical faults do not give rise to zero sequence or negative sequence components because
they are perfectly balanced, symmetrical faults only have positive sequence values.
• Three Phase Line to Ground Fault: The 3-phase to ground faults are faults in where all the phases
(A, B and C) are shorted together and they are grounded.
• Three Phase Line to Line Fault: The three phase faults occur when you have A, B and C phases are
shorted together but ground is not involved.

10. Causes of Power System Faults
Weather Conditions
• The weather factors that typically cause power system faults are: lightning strikes,
accumulation of snow on transmission lines, heavy rains, high speed winds, earthquake, salt
pollution depositing on overhead lines and conductors, floods and fires adjacent to electrical
instrument, etc. These environmental conditions interrupt the power supply and also damage
electrical installations.
Equipment Failures
• Electrical equipment's like machines, motors, generators, transformers, cables, reactors, switch
devices, etc. causes electrical faults. These faults may be caused due to malfunctioning, ageing
and degradation, insulation failure of cables and winding, breakdown due to high switching.
These failures lead to high current to flow through the devices or equipment which further
damages it.

11. Causes of Power System Faults
Human Errors
• Electrical faults are also caused due to human errors like choosing improper rating of
equipment or devices, forgetting metallic or electrical conducting components once coupling
or maintenance, switching the circuit while its below servicing, etc. A classic example is one
wherever maintenance staffs unwittingly leave isolated instrument connected through safety
earth clamps once maintenance work is completed. A three-phase to earth short-circuit fault
occurs when the equipment is re energized to return it to service.
Smoke of Fires​
• The smoke of fires under overhead lines consists of tiny particles results in spark between the
lines or between conductors to insulator. This arc causes insulators to lose their insulting
capability because of high voltages. The hot air in the flames of a fire has a much lower
insulation strength than air at close temperature.

12. Conclusion
Short circuit fault current is many times larger than the normal current. A short circuit is simply
a low resistance connection between the two conductors supplying electrical power to any
circuit. This results in excessive amount of current flow in the power systems through the path
of low resistance and may even cause the power source to be destroyed and causes more heat
and fires. A power system operates under balanced conditions with all equipment's carrying
normal load currents and also the bus voltages inside the prescribed limits. This condition can
be disrupted because of fault within the system. If the electrical fault current exceeds the
interrupting rating of the protective device, the consequences can be devastating. It can be a
serious threat to human life and is capable of causing injury, extensive equipment damage.

13. References
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