This document discusses generator protection techniques. It begins by explaining why protective systems are needed to protect expensive power system elements like generators. It then describes different types of generator faults and various protection schemes. These include stator protection using differential protection and its modifications. Rotor faults and their protections like rotor earth fault protection are also explained. The document provides details on other protections like overcurrent, overvoltage, vibration and overheating protections. It concludes by stating that protective devices help detect faults, notify maintenance, and disconnect faulty elements to ensure continuous and safe operation of power systems.
Unit I: Introduction to Protection System:
Introduction to protection system and its elements, functions of protective relaying, protective zones, primary and backup protection, desirable qualities of protective relaying, basic terminology.
Relays:
Electromagnetic, attracted and induction type relays, thermal relay, gas actuated relay, design considerations of electromagnetic relay.
Unit-II: Relay Application and Characteristics:
Amplitude and phase comparators, over current relays, directional relays, distance relays, differential relay.
Static Relays: Comparison with electromagnetic relay, classification and their description, over current relays, directional relay, distance relays, differential relay.
Unit-III Protection of Transmission Line:
Over current protection, distance protection, pilot wire protection, carrier current protection, protection of bus, auto re-closing,
Unit-IV: Circuit Breaking:
Properties of arc, arc extinction theories, re-striking voltage transient, current chopping, resistance switching, capacitive current interruption, short line interruption, circuit breaker ratings.
Testing Of Circuit Breaker: Classification, testing station and equipments, testing procedure, direct and indirect testing.
Unit-V Apparatus Protection:
Protection of Transformer, generator and motor.
Circuit Breaker: Operating modes, selection of circuit breakers, constructional features and operation of Bulk Oil, Minimum Oil, Air Blast, SF6, Vacuum and d. c. circuit breakers.
Unit I: Introduction to Protection System:
Introduction to protection system and its elements, functions of protective relaying, protective zones, primary and backup protection, desirable qualities of protective relaying, basic terminology.
Relays:
Electromagnetic, attracted and induction type relays, thermal relay, gas actuated relay, design considerations of electromagnetic relay.
Unit-II: Relay Application and Characteristics:
Amplitude and phase comparators, over current relays, directional relays, distance relays, differential relay.
Static Relays: Comparison with electromagnetic relay, classification and their description, over current relays, directional relay, distance relays, differential relay.
Unit-III Protection of Transmission Line:
Over current protection, distance protection, pilot wire protection, carrier current protection, protection of bus, auto re-closing,
Unit-IV: Circuit Breaking:
Properties of arc, arc extinction theories, re-striking voltage transient, current chopping, resistance switching, capacitive current interruption, short line interruption, circuit breaker ratings.
Testing Of Circuit Breaker: Classification, testing station and equipments, testing procedure, direct and indirect testing.
Unit-V Apparatus Protection:
Protection of Transformer, generator and motor.
Circuit Breaker: Operating modes, selection of circuit breakers, constructional features and operation of Bulk Oil, Minimum Oil, Air Blast, SF6, Vacuum and d. c. circuit breakers.
Practical handbook-for-relay-protection-engineersSARAVANAN A
The ‘Hand Book’ covers the Code of Practice in Protection Circuitry including standard lead and device numbers, mode of connections at terminal strips, colour codes in multicore cables, Dos and Donts in execution. Also, principles of various protective relays and schemes including special protection schemes like differential,
restricted, directional and distance relays are explained with sketches. The norms of protection of generators, transformers, lines & Capacitor Banks are also given.
Tutorial on Distance and Over Current ProtectionSARAVANAN A
Contents
• Protection Philosophy of ERPC
• Computation of Distance Relay Setting
• System Study to Understand Distance Relay
Behaviour
• DOC and DEF for EHV system
Main equipment in the power plant is Generator. It's cost is much higher than any other equipment so we will have to protect the generator from all the possible faults and errors.
Functions and Performance Requirements
Elements of an Excitation System
Types of Excitation Systems
Control and Protection Functions
Modeling of Excitation Systems
The functions of an excitation system are
to provide direct current to the synchronous generator field winding, and
to perform control and protective functions essential to the satisfactory operation of the power system
The performance requirements of the excitation system are determined by
Generator considerations:
supply and adjust field current as the generator output varies within its continuous capability
respond to transient disturbances with field forcing consistent with the generator short term capabilities:
rotor insulation failure due to high field voltage
rotor heating due to high field current
stator heating due to high VAR loading
heating due to excess flux (volts/Hz)
Power system considerations:
contribute to effective control of system voltage and improvement of system stability
Protection of transmission lines (distance)Rohini Haridas
This gives idea about necessity of protection of transmission line and protection based on time grading as well as on current grading. Also includes three step distance protection of transmission line
To sense/detect the fault occurrence and other abnormal conditions at the protected equipment/area/section.
To operate the correct circuit breakers so as to disconnect only the faulty equipment/area/section as quickly as possible, thus minimizing the damage caused by the faults.
To operate the correct circuit breakers to isolate the faulty equipment/area/section from the healthy system in the case of abnormalities like overloads, unbalance, undervoltage, etc.
To clear the fault before the system becomes unstable.
To identify distinctly where the fault has occurred.
Practical handbook-for-relay-protection-engineersSARAVANAN A
The ‘Hand Book’ covers the Code of Practice in Protection Circuitry including standard lead and device numbers, mode of connections at terminal strips, colour codes in multicore cables, Dos and Donts in execution. Also, principles of various protective relays and schemes including special protection schemes like differential,
restricted, directional and distance relays are explained with sketches. The norms of protection of generators, transformers, lines & Capacitor Banks are also given.
Tutorial on Distance and Over Current ProtectionSARAVANAN A
Contents
• Protection Philosophy of ERPC
• Computation of Distance Relay Setting
• System Study to Understand Distance Relay
Behaviour
• DOC and DEF for EHV system
Main equipment in the power plant is Generator. It's cost is much higher than any other equipment so we will have to protect the generator from all the possible faults and errors.
Functions and Performance Requirements
Elements of an Excitation System
Types of Excitation Systems
Control and Protection Functions
Modeling of Excitation Systems
The functions of an excitation system are
to provide direct current to the synchronous generator field winding, and
to perform control and protective functions essential to the satisfactory operation of the power system
The performance requirements of the excitation system are determined by
Generator considerations:
supply and adjust field current as the generator output varies within its continuous capability
respond to transient disturbances with field forcing consistent with the generator short term capabilities:
rotor insulation failure due to high field voltage
rotor heating due to high field current
stator heating due to high VAR loading
heating due to excess flux (volts/Hz)
Power system considerations:
contribute to effective control of system voltage and improvement of system stability
Protection of transmission lines (distance)Rohini Haridas
This gives idea about necessity of protection of transmission line and protection based on time grading as well as on current grading. Also includes three step distance protection of transmission line
To sense/detect the fault occurrence and other abnormal conditions at the protected equipment/area/section.
To operate the correct circuit breakers so as to disconnect only the faulty equipment/area/section as quickly as possible, thus minimizing the damage caused by the faults.
To operate the correct circuit breakers to isolate the faulty equipment/area/section from the healthy system in the case of abnormalities like overloads, unbalance, undervoltage, etc.
To clear the fault before the system becomes unstable.
To identify distinctly where the fault has occurred.
In a generating station the generator and transformer are the most expensive equipments and hence it is desirable to employ protective system to isolate the faulty equipment as quickly as possible to keep the healthy section in normal operation and to ensure uninterruptable power supply.
Generator and Transformer Protection (PART 1)Dr. Rohit Babu
Part 1. Generator Protection
Protection of generators against stator faults
Rotor faults and abnormal conditions
Restricted earth fault and inter-turn fault protection
Numerical examples
Ground faults in generator stator and field/rotor circuits are serious events that can lead to damage, costly repair, extended outage and loss of revenue.
This paper explores advances in field/rotor circuit ground fault and stator ground fault protection. These advanced protection strategies employ AC injection and other tactics to provide benefits in security, sensitivity and speed.
This Presentation gives information on How Generator in Power Plants are protected with State of art technologies. Also provide information how latest Power System Protection technologies are more reliable operation.
Rotor earth fault protection of electric generatorCS V
As the field is operated ungrounded, a single fault does not cause any flow of current or affect the operation of the electric generator. However, a single rotor earth fault increases the stress to the ground in the field
The Roman Empire A Historical Colossus.pdfkaushalkr1407
The Roman Empire, a vast and enduring power, stands as one of history's most remarkable civilizations, leaving an indelible imprint on the world. It emerged from the Roman Republic, transitioning into an imperial powerhouse under the leadership of Augustus Caesar in 27 BCE. This transformation marked the beginning of an era defined by unprecedented territorial expansion, architectural marvels, and profound cultural influence.
The empire's roots lie in the city of Rome, founded, according to legend, by Romulus in 753 BCE. Over centuries, Rome evolved from a small settlement to a formidable republic, characterized by a complex political system with elected officials and checks on power. However, internal strife, class conflicts, and military ambitions paved the way for the end of the Republic. Julius Caesar’s dictatorship and subsequent assassination in 44 BCE created a power vacuum, leading to a civil war. Octavian, later Augustus, emerged victorious, heralding the Roman Empire’s birth.
Under Augustus, the empire experienced the Pax Romana, a 200-year period of relative peace and stability. Augustus reformed the military, established efficient administrative systems, and initiated grand construction projects. The empire's borders expanded, encompassing territories from Britain to Egypt and from Spain to the Euphrates. Roman legions, renowned for their discipline and engineering prowess, secured and maintained these vast territories, building roads, fortifications, and cities that facilitated control and integration.
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Culturally, the Romans were eclectic, absorbing and adapting elements from the civilizations they encountered, particularly the Greeks. Roman art, literature, and philosophy reflected this synthesis, creating a rich cultural tapestry. Latin, the Roman language, became the lingua franca of the Western world, influencing numerous modern languages.
Roman architecture and engineering achievements were monumental. They perfected the arch, vault, and dome, constructing enduring structures like the Colosseum, Pantheon, and aqueducts. These engineering marvels not only showcased Roman ingenuity but also served practical purposes, from public entertainment to water supply.
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Ethnobotany in herbal drug evaluation,
Impact of Ethnobotany in traditional medicine,
New development in herbals,
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The French Revolution, which began in 1789, was a period of radical social and political upheaval in France. It marked the decline of absolute monarchies, the rise of secular and democratic republics, and the eventual rise of Napoleon Bonaparte. This revolutionary period is crucial in understanding the transition from feudalism to modernity in Europe.
For more information, visit-www.vavaclasses.com
The Indian economy is classified into different sectors to simplify the analysis and understanding of economic activities. For Class 10, it's essential to grasp the sectors of the Indian economy, understand their characteristics, and recognize their importance. This guide will provide detailed notes on the Sectors of the Indian Economy Class 10, using specific long-tail keywords to enhance comprehension.
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The Art Pastor's Guide to Sabbath | Steve ThomasonSteve Thomason
What is the purpose of the Sabbath Law in the Torah. It is interesting to compare how the context of the law shifts from Exodus to Deuteronomy. Who gets to rest, and why?
How to Create Map Views in the Odoo 17 ERPCeline George
The map views are useful for providing a geographical representation of data. They allow users to visualize and analyze the data in a more intuitive manner.
2024.06.01 Introducing a competency framework for languag learning materials ...Sandy Millin
http://sandymillin.wordpress.com/iateflwebinar2024
Published classroom materials form the basis of syllabuses, drive teacher professional development, and have a potentially huge influence on learners, teachers and education systems. All teachers also create their own materials, whether a few sentences on a blackboard, a highly-structured fully-realised online course, or anything in between. Despite this, the knowledge and skills needed to create effective language learning materials are rarely part of teacher training, and are mostly learnt by trial and error.
Knowledge and skills frameworks, generally called competency frameworks, for ELT teachers, trainers and managers have existed for a few years now. However, until I created one for my MA dissertation, there wasn’t one drawing together what we need to know and do to be able to effectively produce language learning materials.
This webinar will introduce you to my framework, highlighting the key competencies I identified from my research. It will also show how anybody involved in language teaching (any language, not just English!), teacher training, managing schools or developing language learning materials can benefit from using the framework.
2. INTRODUCTION :
It is imperative need to install some protective system to protect the
expensive elements of modern power system such as generators,
transformers, station bus-bars, transmission lines etc. from different types
of faults which are likely to occur sooner & later.
In generating station, as a continuous operation of generators is much
more necessary so the faulty part has to be cleared very quickly for
uninterruptable power supply. Unlike other apparatus, opening a breaker
to isolate the faulty generator is not sufficient to prevent further damage.
The basic electrical quantities those are likely to change during abnormal
fault conditions are current, voltage, phase angle and frequency .
Protective elements utilizes one or more of these quantities to detect
abnormal conditions in a power system for taking further essential steps
to isolate the faulty equipment to keep the healthy part in normal working
condition.
3. GENERATOR FAULTS AND PROTECTION TECHNIQUES :
Generator Faults Can be Considered Under The Following Heads :
i. Stator Winding Faults
ii. Field Winding or Rotor Circuit Faults
iii. Abnormal Operating Conditions
Followings Are The Different Process of Protecting Generator :
i. Stator Protection
ii. Overload or Overcurrent Protection
iii. Overvoltage Protection
iv. Overspeed Protection
v. Protection Against Motoring
vi. Rotor Fault Protection
vii. Negative Sequence Protection Against Unbalanced Loads
viii. Protection Against Vibration
ix. Bearing Overheating Protection
x. External Fault Back-Up Protection
4. STATOR FAULTS AND ITS PROTECTION :
Stator faults include the following-
i. Phase-to-earth faults
ii. Phase-to-phase faults
iii. Inter-turn faults
Phase-to-phase faults & Inter-turn faults are less common, these generally
develop into an earth-faults. Inter-turn faults are more difficult to be detected.
The Different Protection Schemes for Stator Protection are :
i. Differential Protection
ii. Modified Differential Protection
iii. Biased Circulating Current Protection
iv. Self Balance Protection System
v. Balanced Earth-Fault Protection
vi. Stator Inter-Turn Protection
vii. Stator Overheating protection
5. DIFFERENTIAL PROTECTION :
Two sets of identical CTs, each set is mounted on either side of
stator phase winding. The secondaries of these current
transformer sets are connected in star & their ends are connected
through pilot wires (shown in fig).
At normal operating conditions, the currents at the two ends of
the protected section are same (I1=I2). So relay will not operate.
When the fault occurs the balance is disturbed and differential
current (I1-I2) flows through the operating coil of the relay
causing relay operation and the trip circuit of the circuit breaker
is closed.
The relays employed in this protection scheme are generally of
electro-magnetic type & are arranged for instantaneous
operation as faults are expected to be cleared as quick as possible
7. MODIFIED DIFFERENTIAL PROTECTION :
Generally protection is made for
80 to 85% of the winding in
Differential Protection scheme.
If any fault occurs near the
neutral point then the fault
current is very small and relay
does not operate.
Modified differential protection
scheme is used to over come this.
Two phase elements (PC and
PA) and balancing resistor(BR)
is connected in star and the
earth relay(ER) is connected
between the star point and
neutral pilot wire.
8. RESTRICTED OR BALANCED EARTH FAULT PROTECTION :
In case of small size generators
the neutral end of 3 phase
winding is not available
because it is made inside the
generator and grounded through
some low resistance then
percentage differential relay for
ground fault is provided and is
known as restricted earth fault
protection.
This scheme can be used only for
ground faults but not for phase
faults.
10. OVERCURRENT OVERVOLTAGE
PROTECTION PROTECTION
Overloading of the generators Overvoltage protection is required
may be caused either due to in case of hydro-electric or gas
turbine generators but not in case
i. Partial breakdown of of turbo generators.
winding insulation Over voltage may be caused due to-
ii. Excessive load on the
power supply system i. Transient over voltage in
the transmission line due
In occurrence of such to lightening.
faults, the generator can be ii. Defective operation of
disconnected from the system the voltage regulator.
manually. iii. Sudden loss of load due
In modern alternators it has to line tripping.
not so much importance though The protection is provided with an
unnecessary overloading over voltage relay.
interfere with the continuity of It is usually of induction pattern
the supply with an IDMT Characteristic
11. ROTOR FAULTS AND ITS PROTECTION :
Faults in the rotor circuit may be either earth faults or between the turns of
the field winding .
Field circuits are normally operated un-earthed. So a single earth fault will
not affect its operation.
But when a second fault arises then field winding is short circuited and
produce unsymmetrical field system which leads to unbalanced forces on
rotor and results in excess pressure and bearing and shaft distortion.
The Different Protection Schemes for Rotor Protection are
i. Rotor Earth Fault Protection
ii. Loss of Excitation Protection
iii. Protection Against Rotor Overheating because of Over excitation
iv. Rotor Temperature Alarm
v. Automatic Field Suppression & Use of Natural Circuit Breaker
vi. Alternative Arrangement of Field Suppression
12. ROTOR EARTH FAULT PROTECTION :
A high resistance is connected across
the rotor circuit and its mid point is
grounded through a sensitive relay.
The another method of rotor earth
fault protection is done by
i. DC injection method
ii. AC injection method
The dc or ac voltage is impressed
between the field circuit and ground
through a sensitive overvoltage relay
and current limiting resistor or
capacitor(in case of ac).
A single earth fault in rotor circuit
will complete the path and the fault
is sensed by the relay.
DC injection method is simple & has
no problems of leakage current.
13. LOSS OF EXCITATION PROTECTION :
It is caused by accidental tripping of
field breaker, short-circuit in the field
circuits, poor brush contact or
operating errors.
In absence of field current alternators
runs as an induction generator &
currents are inducted in the rotor teeth
and wedges & also draws reactive
power from the system.
Under-current moving coil relay is
connected in series with field winding
for loss of excitation protection.
The relay mostly used for this type of
protection is Directional distance type
relay.
14. ROTOR OVERHEATING PROTECTION BY TEMPERATURE ALARM :
This type of protection
scheme is installed generally
in large alternators.
It indicates the level of
temperature but not the
actual hot spot temperature.
The relay measures the
temperature by measuring
the resistance .(as shown in
fig).
The relay measures the ratio
of voltage & current.
15. AUTOMATIC FIELD SUPPRESSION AND USE OF NEUTRAL
CIRCUIT BREAKER :
In case of a fault in the
generator and though the
circuit breaker is tripped ,the
fault continues to fed as long
as excitation will exist because
emf is induced in the generator
itself.
Hence all protection system not
only trip the generator circuit
breaker but also trip the
“automatic field discharge
switch “
16. NEGATIVE PHASE SEQUENCE PROTECTION :
Unbalance may cause due to single phase fault or unbalanced
loading and it gives rise to negative sequence current .
This current in rotor causes rotor overheating and damage to the
rotor.
This can be protected by negative sequence current filter with
over current relay.
17. EXTERNAL FAULT BACK UP PROTECTION :
Over-current and earth-fault protection is provided for back-up protection of
large sized generators protected by differential protection against external
phase-to-phase faults & earth faults.
Induction type IDMT relay is used for this purpose.
High se, definite minimum time, induction type, inverse over-current, earth
fault relays are required for back-up protection of generators.
18. PROTECTION AGAINST VIBRATION AND BEARING
OVERHEATING PROTECTION :
Rotor earth fault protection & Negative sequence protection of
generator against unbalanced loads prevent vibration under those
circumstances.
A vibration detector mounted on one of the bearing pedestals & on
one of the upper guide bearing in case of horizontal & vertical shaft
generating set respectively.
Bearing overheating can be detected by a relay accounted by
i. A thermometer-type bulb inserted in the hole of the bearing
ii. A resistance-temperature-detector relay
If lubricating oil is circulated through the bearing under pressure, the
oil temperature should be taken into account for an alarm if oil
circulation is stopped
19. CONCLUSION :
Switchgears & other protective devices are used in the
electrical machines & in the power system elements
i. To detect the abnormal faulty condition
ii. To notify this information to the maintenance officer
of that factory or generation station
iii. To disconnect the faulty elements from the healthy
system or shutdown the faulted apparatus for
continuous operation of the machines, for safety of
this expensive electrical devises as well as for the
safety of the workers
The protective device does not prevent the cause of fault or
does not prevent ta occurrence of fault , it is used after the
occurrence of fault for quick action to remove those faulty
section for further normal operation .
20. REFERENCES :
A Course In Power Systems
by J.B.Gupta
Modern power System Analysis
by D.P.Kothari & I.J.Nagrath
www.wikipedia.com
www.google.co.in
