This document provides an introduction to power system protection. It discusses the need for protection systems to detect and isolate faults to minimize damage. Short circuits can occur due to insulation failures, contamination, or mechanical issues. Protection systems aim to continue supply to the rest of the system while protecting faulty equipment. The types of protection discussed include fuses, overcurrent, differential, distance, and miscellaneous protections. Design criteria for protection systems include simplicity, economy, speed, reliability, sensitivity and selectivity. System protection components, zones of protection, and fault currents and voltages are also introduced.
The document discusses differential protection principles and schemes. It describes how differential protection compares currents on the primary and secondary sides of a transformer to detect internal faults. A basic differential scheme directly compares currents but can operate due to CT ratio mismatches or inrush currents. A bias/restraining differential scheme uses an operating coil to detect differential currents and a restraining coil to prevent operation due to through currents. It provides examples of calculating currents and determining if relays would operate for different faults.
This document discusses overcurrent protection and different types of overcurrent relays. It describes the causes and effects of overcurrent, and introduces overcurrent protection using fuses, circuit breakers and overcurrent relays. It explains the operating principles of different types of overcurrent relays including attracted armature, definite time, and inverse definite minimum time (IDMT) relays. Examples are provided to illustrate how to select settings for IDMT relays in a power system to achieve coordinated overcurrent protection.
This document discusses auto-reclosing, which aims to minimize power interruptions by automatically reconnecting faulty lines after faults. It describes the benefits of auto-reclosing such as reduced outages and manpower. It also discusses different types of faults and various auto-reclosing schemes for transient, permanent, and EHV transmission line faults. Factors considered for high speed auto-reclosing include protection characteristics, de-ionization time, circuit breaker performance, and reclaim time. Single phase auto-reclosing is also covered. The document concludes by describing features of auto-reclosing schemes and examples of auto-isolation in single switch and 4 switch mesh corner substations.
The document provides information about a course on power systems analysis and protection. It includes:
1. An overview of topics covered in the course including per-unit systems, power flow analysis, fault analysis, stability, and protection schemes.
2. Expected learning outcomes including analyzing balanced and unbalanced faults, demonstrating power flow software, and expressing suitable protection schemes.
3. A lecture plan outlining the contents to be covered each week.
4. Assessment details including oral exams, written tests, assignments, and a final exam.
The document discusses protection and coordination of electrical equipment. It covers objectives like human safety, equipment protection, system protection and selectivity. It describes various protection types like overcurrent, differential and distance protection. It also discusses coordination techniques like time-current curves and provides examples of protective devices for low voltage equipment like circuit breakers, fuses and motors.
The document discusses relay coordination and grading methods for protective relays in power systems. It describes various coordination techniques including current grading, time grading, and a combination of time and current grading using inverse definite minimum time (IDMT) characteristics. The key aspects covered are:
1) Current grading sets relays closer to the power source to operate at higher fault currents. Time grading sets relays to operate at progressively longer times closer to the source.
2) IDMT coordination uses inverse-time overcurrent relays set to different time multiples and pickup currents to achieve coordination over a wide range of fault levels.
3) Proper coordination requires isolating the faulty section, preventing tripping of healthy equipment, and
The document summarizes the different generations of electrical relays used in digital protection systems. It discusses fuse relays, electromechanical relays, solid state relays, digital relays, adaptive digital relays, multifunction relays, and intelligent relays. Electromechanical relays were prone to failures over time but newer digital and solid state relays are more reliable with no moving parts. Digital relays allow for more complex functions, self-testing, and communication compared to earlier relay technologies. Adaptive digital relays can automatically adjust settings based on changes in power system conditions. Multifunction relays provide multiple protection functions in a single unit to reduce space and wiring needs. Intelligent relays allow customers to change
Power Transformer Differential protectionRishi Tandon
This document discusses power transformer protection. It begins by explaining that transformers are static devices that transform electrical energy between circuits without changing frequency. Power transformers are vital but expensive components that are difficult to repair if damaged. Transformer protection is needed to prevent severe damage from faults and ensure continuous network operation. Common fault types and causes are then outlined, including insulation breakdown, overheating, contamination, and phase/turn faults. The document proceeds to describe the general scheme of differential protection and specific protection functions like bias differential, overfluxing, over/under voltage, and restricted earth fault protection. It provides an example calculation for setting a transformer differential relay and diagrams demonstrating differential relay operation. Finally, it reviews models from various manufacturers and presents a case study
The document discusses differential protection principles and schemes. It describes how differential protection compares currents on the primary and secondary sides of a transformer to detect internal faults. A basic differential scheme directly compares currents but can operate due to CT ratio mismatches or inrush currents. A bias/restraining differential scheme uses an operating coil to detect differential currents and a restraining coil to prevent operation due to through currents. It provides examples of calculating currents and determining if relays would operate for different faults.
This document discusses overcurrent protection and different types of overcurrent relays. It describes the causes and effects of overcurrent, and introduces overcurrent protection using fuses, circuit breakers and overcurrent relays. It explains the operating principles of different types of overcurrent relays including attracted armature, definite time, and inverse definite minimum time (IDMT) relays. Examples are provided to illustrate how to select settings for IDMT relays in a power system to achieve coordinated overcurrent protection.
This document discusses auto-reclosing, which aims to minimize power interruptions by automatically reconnecting faulty lines after faults. It describes the benefits of auto-reclosing such as reduced outages and manpower. It also discusses different types of faults and various auto-reclosing schemes for transient, permanent, and EHV transmission line faults. Factors considered for high speed auto-reclosing include protection characteristics, de-ionization time, circuit breaker performance, and reclaim time. Single phase auto-reclosing is also covered. The document concludes by describing features of auto-reclosing schemes and examples of auto-isolation in single switch and 4 switch mesh corner substations.
The document provides information about a course on power systems analysis and protection. It includes:
1. An overview of topics covered in the course including per-unit systems, power flow analysis, fault analysis, stability, and protection schemes.
2. Expected learning outcomes including analyzing balanced and unbalanced faults, demonstrating power flow software, and expressing suitable protection schemes.
3. A lecture plan outlining the contents to be covered each week.
4. Assessment details including oral exams, written tests, assignments, and a final exam.
The document discusses protection and coordination of electrical equipment. It covers objectives like human safety, equipment protection, system protection and selectivity. It describes various protection types like overcurrent, differential and distance protection. It also discusses coordination techniques like time-current curves and provides examples of protective devices for low voltage equipment like circuit breakers, fuses and motors.
The document discusses relay coordination and grading methods for protective relays in power systems. It describes various coordination techniques including current grading, time grading, and a combination of time and current grading using inverse definite minimum time (IDMT) characteristics. The key aspects covered are:
1) Current grading sets relays closer to the power source to operate at higher fault currents. Time grading sets relays to operate at progressively longer times closer to the source.
2) IDMT coordination uses inverse-time overcurrent relays set to different time multiples and pickup currents to achieve coordination over a wide range of fault levels.
3) Proper coordination requires isolating the faulty section, preventing tripping of healthy equipment, and
The document summarizes the different generations of electrical relays used in digital protection systems. It discusses fuse relays, electromechanical relays, solid state relays, digital relays, adaptive digital relays, multifunction relays, and intelligent relays. Electromechanical relays were prone to failures over time but newer digital and solid state relays are more reliable with no moving parts. Digital relays allow for more complex functions, self-testing, and communication compared to earlier relay technologies. Adaptive digital relays can automatically adjust settings based on changes in power system conditions. Multifunction relays provide multiple protection functions in a single unit to reduce space and wiring needs. Intelligent relays allow customers to change
Power Transformer Differential protectionRishi Tandon
This document discusses power transformer protection. It begins by explaining that transformers are static devices that transform electrical energy between circuits without changing frequency. Power transformers are vital but expensive components that are difficult to repair if damaged. Transformer protection is needed to prevent severe damage from faults and ensure continuous network operation. Common fault types and causes are then outlined, including insulation breakdown, overheating, contamination, and phase/turn faults. The document proceeds to describe the general scheme of differential protection and specific protection functions like bias differential, overfluxing, over/under voltage, and restricted earth fault protection. It provides an example calculation for setting a transformer differential relay and diagrams demonstrating differential relay operation. Finally, it reviews models from various manufacturers and presents a case study
This document discusses transformer overcurrent protection calculations and settings. It provides information on:
1. Coordination principles for transformer protection and examples of typical protection zones for different fault locations.
2. Guidelines for setting instantaneous and time-overcurrent relays to ensure selective coordination, including maintaining coordination intervals.
3. Calculations for determining short circuit currents and relay settings for different transformer configurations, including delta-wye transformers. Thermal and mechanical withstand curves for different transformer categories are also presented.
Fundamentals of Power System protection by Y.G.Paithankar and S.R.BhideSourabh Ghosh
This document provides an overview of fundamentals of power system protection. It discusses various types of faults that can occur in power systems such as shunt faults, series faults, and abnormal operating conditions. It describes classification of faults and evolution of protection schemes from isolated to interconnected power systems. Various system transducers such as current transformers, potential transformers and circuit breakers are introduced. Principles of overcurrent, differential, distance and other protection schemes are outlined. Protection of transmission lines, transformers, buses, generators and motors are covered along with numerical protection and static comparators. The document aims to equip students with sound concepts of power system protection to handle real-life scenarios.
Characteristic of idmt curves for overcurrent relaystahseen alshmary
The document discusses inverse-time overcurrent protection relays and their time-current curves. It describes the standard inverse, very inverse, extremely inverse, and long time inverse curves defined by IEC 60255 with their corresponding K and E values. It then provides examples of calculating the operating times for different relay types and settings based on the inverse-time equations, for short circuit currents of 2, 4, 6, 10, and 20 times the pickup setting.
This document provides an overview of testing solutions and products from OMICRON for electrical power systems. It describes OMICRON's focus on innovation in secondary testing equipment over 20 years. It also outlines OMICRON's global customer support network and commitment to high quality products and services. The catalog then provides detailed information on OMICRON's test sets, software, IEC 61850 testing tools, and accessories.
Overcurrent and Distance Protection in DigSilent PowerFactoryAreeb Abdullah
This project involves the theoretical study of Protection Devices, Protection Schemes, Analysis of Control and Logical Blocks of relays being used in the project and practical implementation of both schemes in DigSilent PowerFactory.
This document provides guidelines for overcurrent protection and coordination settings for industrial equipment such as transformers, buses, feeders, and motors above 600V. It outlines typical recommended pickup and time delay settings as rules of thumb for phase and ground overcurrent relays protecting this equipment. Care must be taken to properly coordinate settings between protective devices to prevent unintended tripping and ensure equipment is protected against damage from faults.
This document discusses upgrading generator protection systems using digital technology. It provides an overview of generator fundamentals and industry standards for protection. Key reasons to upgrade include improved sensitivity to detect faults, adding new protection functions, and using digital relays. Specific protection functions that can be upgraded include negative sequence, field ground fault detection, dual-level loss of field, overexcitation, inadvertent energizing, VT fuse monitoring, and sequential tripping. Digital relays provide benefits like oscillographic monitoring for fault analysis. Special applications like generator breaker failure and over/under frequency protection are also reviewed.
This document discusses various circuit elements used to model real devices, including resistors, sources, open/short circuits, and diodes. It defines ideal circuit elements as having two terminals, being described mathematically by current and voltage, and not being subdividable. Resistors follow Ohm's Law, where voltage is proportional to current. Sources maintain a constant voltage or current regardless of the other parameter. Open and short circuits have zero current or voltage respectively. Diodes only allow current in one direction.
Unit 04 Protection of generators and transformers PremanandDesai
The document discusses faults and protection methods for alternators and transformers. For alternators, common faults include failure of the prime mover, field failure, overcurrent, overspeed, overvoltage, and unbalanced or stator winding faults. Differential and inter-turn protection are described. For transformers, faults include open circuits, overheating, and winding short-circuits. Buchholz devices, earth fault relays, overcurrent relays, and differential systems provide protection. Earth fault protection for transformers uses a core-balance leakage scheme.
This document discusses power transformer protection. It begins by explaining that transformers are static devices that transform electrical energy between circuits without changing frequency. Power transformers are vital but expensive components that are difficult to repair if damaged. Protection is needed to prevent severe damage from faults.
It then describes the types of faults as incipient, internal, or external. Potential causes of faults are listed as insulation breakdown, overheating, oil contamination, reduced cooling, and phase/ground faults.
The document outlines the general scheme of differential protection and lists specific protection functions used. It provides an example calculation for setting a transformer differential relay and describes the relay's operating characteristics. Models of differential protection relays from various manufacturers are also listed.
Unit 03 Construction & Operation of Watt meter & Energy meterPremanandDesai
An induction watt-hour meter measures electrical energy consumption by using two electromagnets to induce eddy currents in an aluminum disk and rotate it. The disk's rotation is proportional to energy used and is registered to indicate kilowatt-hours. It works by using a series coil carrying load current and a shunt coil carrying voltage-proportional current to generate a rotating magnetic field. This field interacts with eddy currents in the disk to provide a driving torque while a brake magnet provides a braking torque proportional to disk speed. Errors can occur due phase shifts or other issues, but the meter can be adjusted to ensure accurate readings.
single phase ac voltage controller with RL loadKathanShah32
AC voltage controllers use pairs of thyristors like SCRs or triacs to control the voltage output without changing frequency. Voltage control is accomplished through either phase control under natural commutation or on/off control under forced commutation using devices like GTOs, transistors, or IGBTs. The document then describes how a single phase AC voltage controller with an RL load uses two thyristors (T1 and T2) to control the output voltage by varying the firing angle (a) of each thyristor during the positive and negative half cycles.
This document provides an overview of transformer protection. It discusses the types of faults that can occur in transformers, including internal faults like winding faults and external faults. It describes Buchholz relays, which detect faults inside the transformer tank by sensing gas and oil movement. Differential protection is also covered, which can detect faults not caught by Buchholz relays. The document outlines considerations for transformer differential protection like current transformer ratings and connections. It provides examples of Merz-Price protection schemes for star-delta and star-star transformers.
This document provides an introduction to medium voltage (MV) equipment, including key concepts such as:
- Voltage levels including operating voltage, rated voltage, insulation levels, and derating factors
- Current levels including operating current, short circuit current, and thermal withstand current
- Frequency standards of 50Hz and 60Hz
- Types of MV switchgear including air insulated switchgear, metal enclosed, compartmented, and block types
- Standards that MV switchgear must comply with such as IEC 62271
- Main functions of switchgear including protection, isolation, and control
- Comparison of SF6 and vacuum circuit breaker technologies
The document concisely covers the essential electrical concepts and specifications
EDS Unit 4 (Protection and Coordination).pptxDr. Rohit Babu
Protection:
Objectives of distribution system protection
Types of common faults and procedure for fault calculations
Protective devices: Principle of operation of fuses Circuit reclosures
Line sectionalizes and circuit breakers.
Coordination:
Coordination of protective devices: General coordination procedure
Residual current circuit breaker RCCB (Wikipedia).
Power System protection and Metering,Types of Faults and effects,Symmetrical faults,Unsymmetrical faults,Fault Statics,Components of power System protection,Relay,Classification of Relay,Induction relay,thermal relay,Static Relay,Numerical Relay
The document summarizes instrument transformers, which are used to isolate protection, control, and measurement equipment from high voltages in power systems. It discusses current transformers (CTs) and potential transformers (PTs). CTs reduce system current to a lower value for measurement. They function by inducing a current in a secondary winding from the magnetic field of a primary winding connected to the power circuit. PTs provide isolation from high voltages and measure voltage. They have errors in voltage ratio and phase angle between primary and secondary voltages.
The document discusses over current protection in electrical systems. It describes over current as a situation where excess current flows through a conductor, risking heat generation and equipment damage. Possible causes of over current include short circuits, excessive load, incorrect design, or ground faults. Over current relays protect systems by detecting excess current from current transformers and tripping circuit breakers. Relays are classified based on their time of operation as instantaneous, definite time, or inverse time relays. The document outlines various over current protection schemes used in electrical equipment like transformers and generators.
This document discusses short-circuit calculations, protective device coordination, and arc flash analysis. It covers topics such as short-circuit fault types and calculations, the purpose of short-circuit studies, system components involved, and protective device coordination principles. Methods to perform arc flash analysis and mitigate incident energy exposure are also examined, such as improving coordination settings, installing current limiting fuses or circuit breakers, and using Type 50 protective devices.
This document provides an overview of a training session on protection fundamentals presented by Craig Wester and John Levine of GE Multilin. The training covers protection tools, demonstration relays, future training classes, and protection fundamentals. The fundamentals section discusses desirable protection attributes, selection of protective relays, primary equipment components, and various types of protection including overcurrent, differential, voltage, frequency, power, and distance protection. Information required for applying protection is also listed.
This document discusses transformer overcurrent protection calculations and settings. It provides information on:
1. Coordination principles for transformer protection and examples of typical protection zones for different fault locations.
2. Guidelines for setting instantaneous and time-overcurrent relays to ensure selective coordination, including maintaining coordination intervals.
3. Calculations for determining short circuit currents and relay settings for different transformer configurations, including delta-wye transformers. Thermal and mechanical withstand curves for different transformer categories are also presented.
Fundamentals of Power System protection by Y.G.Paithankar and S.R.BhideSourabh Ghosh
This document provides an overview of fundamentals of power system protection. It discusses various types of faults that can occur in power systems such as shunt faults, series faults, and abnormal operating conditions. It describes classification of faults and evolution of protection schemes from isolated to interconnected power systems. Various system transducers such as current transformers, potential transformers and circuit breakers are introduced. Principles of overcurrent, differential, distance and other protection schemes are outlined. Protection of transmission lines, transformers, buses, generators and motors are covered along with numerical protection and static comparators. The document aims to equip students with sound concepts of power system protection to handle real-life scenarios.
Characteristic of idmt curves for overcurrent relaystahseen alshmary
The document discusses inverse-time overcurrent protection relays and their time-current curves. It describes the standard inverse, very inverse, extremely inverse, and long time inverse curves defined by IEC 60255 with their corresponding K and E values. It then provides examples of calculating the operating times for different relay types and settings based on the inverse-time equations, for short circuit currents of 2, 4, 6, 10, and 20 times the pickup setting.
This document provides an overview of testing solutions and products from OMICRON for electrical power systems. It describes OMICRON's focus on innovation in secondary testing equipment over 20 years. It also outlines OMICRON's global customer support network and commitment to high quality products and services. The catalog then provides detailed information on OMICRON's test sets, software, IEC 61850 testing tools, and accessories.
Overcurrent and Distance Protection in DigSilent PowerFactoryAreeb Abdullah
This project involves the theoretical study of Protection Devices, Protection Schemes, Analysis of Control and Logical Blocks of relays being used in the project and practical implementation of both schemes in DigSilent PowerFactory.
This document provides guidelines for overcurrent protection and coordination settings for industrial equipment such as transformers, buses, feeders, and motors above 600V. It outlines typical recommended pickup and time delay settings as rules of thumb for phase and ground overcurrent relays protecting this equipment. Care must be taken to properly coordinate settings between protective devices to prevent unintended tripping and ensure equipment is protected against damage from faults.
This document discusses upgrading generator protection systems using digital technology. It provides an overview of generator fundamentals and industry standards for protection. Key reasons to upgrade include improved sensitivity to detect faults, adding new protection functions, and using digital relays. Specific protection functions that can be upgraded include negative sequence, field ground fault detection, dual-level loss of field, overexcitation, inadvertent energizing, VT fuse monitoring, and sequential tripping. Digital relays provide benefits like oscillographic monitoring for fault analysis. Special applications like generator breaker failure and over/under frequency protection are also reviewed.
This document discusses various circuit elements used to model real devices, including resistors, sources, open/short circuits, and diodes. It defines ideal circuit elements as having two terminals, being described mathematically by current and voltage, and not being subdividable. Resistors follow Ohm's Law, where voltage is proportional to current. Sources maintain a constant voltage or current regardless of the other parameter. Open and short circuits have zero current or voltage respectively. Diodes only allow current in one direction.
Unit 04 Protection of generators and transformers PremanandDesai
The document discusses faults and protection methods for alternators and transformers. For alternators, common faults include failure of the prime mover, field failure, overcurrent, overspeed, overvoltage, and unbalanced or stator winding faults. Differential and inter-turn protection are described. For transformers, faults include open circuits, overheating, and winding short-circuits. Buchholz devices, earth fault relays, overcurrent relays, and differential systems provide protection. Earth fault protection for transformers uses a core-balance leakage scheme.
This document discusses power transformer protection. It begins by explaining that transformers are static devices that transform electrical energy between circuits without changing frequency. Power transformers are vital but expensive components that are difficult to repair if damaged. Protection is needed to prevent severe damage from faults.
It then describes the types of faults as incipient, internal, or external. Potential causes of faults are listed as insulation breakdown, overheating, oil contamination, reduced cooling, and phase/ground faults.
The document outlines the general scheme of differential protection and lists specific protection functions used. It provides an example calculation for setting a transformer differential relay and describes the relay's operating characteristics. Models of differential protection relays from various manufacturers are also listed.
Unit 03 Construction & Operation of Watt meter & Energy meterPremanandDesai
An induction watt-hour meter measures electrical energy consumption by using two electromagnets to induce eddy currents in an aluminum disk and rotate it. The disk's rotation is proportional to energy used and is registered to indicate kilowatt-hours. It works by using a series coil carrying load current and a shunt coil carrying voltage-proportional current to generate a rotating magnetic field. This field interacts with eddy currents in the disk to provide a driving torque while a brake magnet provides a braking torque proportional to disk speed. Errors can occur due phase shifts or other issues, but the meter can be adjusted to ensure accurate readings.
single phase ac voltage controller with RL loadKathanShah32
AC voltage controllers use pairs of thyristors like SCRs or triacs to control the voltage output without changing frequency. Voltage control is accomplished through either phase control under natural commutation or on/off control under forced commutation using devices like GTOs, transistors, or IGBTs. The document then describes how a single phase AC voltage controller with an RL load uses two thyristors (T1 and T2) to control the output voltage by varying the firing angle (a) of each thyristor during the positive and negative half cycles.
This document provides an overview of transformer protection. It discusses the types of faults that can occur in transformers, including internal faults like winding faults and external faults. It describes Buchholz relays, which detect faults inside the transformer tank by sensing gas and oil movement. Differential protection is also covered, which can detect faults not caught by Buchholz relays. The document outlines considerations for transformer differential protection like current transformer ratings and connections. It provides examples of Merz-Price protection schemes for star-delta and star-star transformers.
This document provides an introduction to medium voltage (MV) equipment, including key concepts such as:
- Voltage levels including operating voltage, rated voltage, insulation levels, and derating factors
- Current levels including operating current, short circuit current, and thermal withstand current
- Frequency standards of 50Hz and 60Hz
- Types of MV switchgear including air insulated switchgear, metal enclosed, compartmented, and block types
- Standards that MV switchgear must comply with such as IEC 62271
- Main functions of switchgear including protection, isolation, and control
- Comparison of SF6 and vacuum circuit breaker technologies
The document concisely covers the essential electrical concepts and specifications
EDS Unit 4 (Protection and Coordination).pptxDr. Rohit Babu
Protection:
Objectives of distribution system protection
Types of common faults and procedure for fault calculations
Protective devices: Principle of operation of fuses Circuit reclosures
Line sectionalizes and circuit breakers.
Coordination:
Coordination of protective devices: General coordination procedure
Residual current circuit breaker RCCB (Wikipedia).
Power System protection and Metering,Types of Faults and effects,Symmetrical faults,Unsymmetrical faults,Fault Statics,Components of power System protection,Relay,Classification of Relay,Induction relay,thermal relay,Static Relay,Numerical Relay
The document summarizes instrument transformers, which are used to isolate protection, control, and measurement equipment from high voltages in power systems. It discusses current transformers (CTs) and potential transformers (PTs). CTs reduce system current to a lower value for measurement. They function by inducing a current in a secondary winding from the magnetic field of a primary winding connected to the power circuit. PTs provide isolation from high voltages and measure voltage. They have errors in voltage ratio and phase angle between primary and secondary voltages.
The document discusses over current protection in electrical systems. It describes over current as a situation where excess current flows through a conductor, risking heat generation and equipment damage. Possible causes of over current include short circuits, excessive load, incorrect design, or ground faults. Over current relays protect systems by detecting excess current from current transformers and tripping circuit breakers. Relays are classified based on their time of operation as instantaneous, definite time, or inverse time relays. The document outlines various over current protection schemes used in electrical equipment like transformers and generators.
This document discusses short-circuit calculations, protective device coordination, and arc flash analysis. It covers topics such as short-circuit fault types and calculations, the purpose of short-circuit studies, system components involved, and protective device coordination principles. Methods to perform arc flash analysis and mitigate incident energy exposure are also examined, such as improving coordination settings, installing current limiting fuses or circuit breakers, and using Type 50 protective devices.
This document provides an overview of a training session on protection fundamentals presented by Craig Wester and John Levine of GE Multilin. The training covers protection tools, demonstration relays, future training classes, and protection fundamentals. The fundamentals section discusses desirable protection attributes, selection of protective relays, primary equipment components, and various types of protection including overcurrent, differential, voltage, frequency, power, and distance protection. Information required for applying protection is also listed.
Lec 1_Introduction to Power System
Protection.pdfAhmedHElashry
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
lines, bus bars and others. Short circuits and other
abnormal conditions in the power system are
common and can cause damage to power system
equipment.
Electric power system is composed of the
components or elements such as generators,
transformers, transmission lines and distribution
line
This document provides an overview of power system protection fundamentals presented by John Levine. It covers protection tools, objectives, fundamentals such as reliability and selectivity, common protection types including overcurrent, differential, voltage, frequency, power, and distance protection. It also discusses primary system components, protection zones, applying protection including required information, one-line diagrams, and current and voltage transformer basics. System grounding methods are also reviewed. The presentation aims to help engineers apply protection and make their jobs easier.
This document provides an overview of power system protection fundamentals presented by John Levine. It covers topics such as protection objectives, types of protection including overcurrent, differential, voltage, frequency, power, and distance protection. It also discusses primary system components, protection zones, coordination, information required for protection application, one-line diagrams, current and voltage transformers, grounding methods, and more. The presentation aims to help attendees with protection applications and encourages questions from the audience.
The document discusses various protection schemes for generators. It describes (1) differential protection that protects the stator winding from internal faults, (2) rotor earth fault protection that protects the rotor winding, and (3) loss of excitation protection that protects the power system from instability if the generator loses its field excitation. Various other protections discussed include overcurrent, overvoltage, temperature, and reverse power protections. The document provides details on the operating principles and components of these various generator protection schemes.
This document provides an overview of the course EEE 6903: Advanced Protective Relays. It discusses the contents of the course, which includes reviewing different types of relays and their principles of operation, the effects of transients on relays, harmonic relaying, and applications of static and digital relays. It also provides background on power systems, the need for protective relays, common faults in power systems, and desirable qualities for protective relays such as selectivity, speed, sensitivity, reliability and economy. Key terms related to protective relaying are defined.
Lecture 1. INTRODUCTION TO BASIC PROTECTION AND RELAYING SCHEMES.pptxssuserb444c3
The document discusses power system protection and protective relaying. It covers the need for protection systems to maintain reliable power supply and prevent damage during faults. The key elements of a protection system include protective relays, circuit breakers, transducers, and communication channels. Relays detect faults using principles like overcurrent, directional overcurrent, distance and differential protection. Coordination between primary and backup protection is also discussed. Digital relays offer advantages like multifunctionality, adaptability and reduced maintenance over electromechanical relays. The document emphasizes the importance of properly designing protection schemes for reliable power system operation.
This document discusses power system protection schemes, including:
- Zones of protection with protective relays coordinated between zones
- Attributes of reliable, selective, and fast relaying
- Fault clearing times of relays and circuit breakers
- Protection of system components like feeders, transmission lines, transformers, generators
It provides examples of overcurrent protection design using time-graded and current-graded discrimination. Directional relays, differential protection, and power line carrier communication are also summarized.
- Protective systems are needed for power systems to isolate faulty sections from healthy sections quickly through devices like relays and circuit breakers. This is important to prevent equipment damage and total system failure.
- A good protective system must have selectivity, sensitivity, reliability, stability, and speed to properly identify and clear faults within the critical clearing time. The design is balanced between protecting equipment and keeping costs reasonable. Zones of protection are established at different voltage levels from generation to distribution.
basicprotectionandrelayingbysomaliajaldas-121126030037-phpapp01.pptThien Phan Bản
This document discusses basic protection and relaying schemes used in electric power systems. It begins by explaining why protection is needed to maintain reliable operation during both small and severe disturbances. The key elements of a protection system are then introduced, including protective relays, circuit breakers, and current/voltage sensors. Common types of faults that can occur on power systems are described. The document proceeds to explain various basic protection schemes such as overcurrent, directional, and differential relaying and how they are applied to protect different power system components. Digital relays are noted as having advantages like multifunctionality and adaptability over traditional electromechanical relays.
basicprotectionandrelayingbysomaliajaldas-121126030037-phpapp01.pptThien Phan Bản
This document discusses basic protection and relaying schemes used in electric power systems. It begins by explaining why protection is needed to handle both small and severe disturbances. The key elements of a protection system are then introduced, including protective relays, circuit breakers, and current/voltage transducers. Common fault types and the high currents they produce are described. The document goes on to explain various basic protection schemes like overcurrent, directional, distance, and differential protection. It also covers relay types, applications of inverse-time relays, and coordination between protection devices. Digital relays provide benefits like multifunctionality, adaptability, and reduced equipment burden. Protection schemes are crucial to maintain reliable power system operation during normal and fault
The document provides an overview of protective relaying. It discusses the knowledge required for protective relaying including equipment behavior, faults, protection philosophies and terminology. It describes power system components that require protection like generators, transformers, transmission lines etc. The objectives, philosophy and requirements of protection schemes are explained. The document discusses zones of protection, primary and backup protection. It also covers protective relay inputs, outputs, settings, and characteristics. The evolution of relay technology from electromechanical to solid state to numerical relays using microprocessors is summarized.
System protection detects problems on the power system like short circuits, abnormal conditions, and equipment failures. It protects components like generators, transformers, transmission lines, buses, and capacitors. Protective relays monitor current and voltage to detect issues. Current and potential transformers scale currents and voltages for relay inputs. Generator protection methods include differential, impedance, and voltage relays. Transformer protection uses fuses, overcurrent, and differential schemes. Transmission line protection employs overcurrent, directional, distance, and pilot schemes like blocking and permissive transfer trip to isolate faults.
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.
This document provides an introduction to basic electrical concepts. It discusses various electrical careers including electricians, residential electricians, industrial/commercial electricians, telecommunications technicians, outside linemen, and electronics technicians. It also describes common electrical components such as resistors, capacitors, inductors, transformers, switches, fuses, and circuit breakers. Additionally, it covers electrical meters, units of measurement, engineering notation, and how to use a digital multimeter and volt-ohm-meter to measure electrical properties. The document provides examples and questions to check the reader's understanding of these foundational electrical concepts.
Unit 05 Protection of feeders and bus-bars PremanandDesai
1. Faults are more common in transmission lines than other electrical equipment due to lines running through open atmosphere over long distances. Common faults include overloads, earth faults, and line-to-line faults.
2. Protection schemes for feeders and lines include time-graded overcurrent protection using definite time or inverse time relays to isolate only the faulty section. Differential pilot-wire protection compares currents at both ends of a line and trips breakers if they are unequal due to an internal fault.
3. Distance or impedance protection is used for very long extra-high voltage lines as other schemes provide slow fault clearance or are too expensive. It relies on measuring the voltage-current ratio to determine the
Feeder protection systems aim to safely and reliably isolate faults while maintaining power supply. Unit and non-unit schemes are used. Non-unit schemes include time-graded overcurrent protection which operates relays closer to faults first. Distance and impedance relays also detect faults within a set distance. Earth fault protection separately monitors ground faults. Protection coordination is important to isolate only faulty areas.
This document provides an introduction to basic electrical concepts. It discusses various electrical careers including electricians, residential electricians, industrial/commercial electricians, telecommunications technicians, outside linemen, and electronics technicians. It also describes common electrical components such as resistors, capacitors, inductors, transformers, switches, fuses, and circuit breakers. Additionally, it covers electrical meters, units of measurement, and engineering notation for representing large and small numbers. Check questions are included to test the reader's understanding.
Similar to 2_Intro Protection + Protection CT.pdf (20)
This document summarizes inverters and their operation. It begins with an introduction that defines inverters as devices that convert DC to AC power by switching the DC input voltage in a predetermined sequence. It then discusses the basic principles of inverters including single-phase half-bridge and full-bridge inverter circuits. Fourier series analysis is introduced as a tool to analyze the output waveforms of inverters in terms of harmonic components. The document concludes with a discussion of total harmonic distortion as a measure of output waveform quality.
This document discusses single-phase and three-phase rectifiers. It describes how a single-phase half-wave rectifier works by only allowing current to flow during one half of the AC cycle. Waveforms are provided for the voltage and current. When an inductive load is used, the current remains continuous. Performance parameters for rectifiers include efficiency, form factor, ripple factor, and total harmonic distortion. Three-phase bridge rectifiers are also covered.
chapter_1 Intro. to electonic Devices.pptLiewChiaPing
The document discusses power electronics concepts and devices. It begins with an introduction to power electronics and outlines various power electronic converters including controlled rectifiers, choppers, inverters, cycloconverters, and AC voltage controllers. It then discusses applications of power electronic converters in various industries. The document also describes several power semiconductor devices used in power electronics, such as power diodes, transistors, MOSFETs, IGBTs, thyristors, GTOs, and IGCTs. It covers the characteristics, ratings, and drive circuits of these devices.
Chapter 7 Application of Electronic Converters.pdfLiewChiaPing
This document discusses power electronics applications in DC and AC drives. It describes the basic characteristics and equivalent circuits of DC motors and how their speed can be controlled through various single-phase and three-phase converter configurations. It also summarizes the operation of induction motors, including cage and slip-ring types, and how their speed can be controlled through variable frequency inverters or by adjusting the slip-ring voltage. The document concludes by outlining the main components of HVDC converter stations used for long distance and asynchronous power transmission.
This document discusses AC-AC controllers that convert AC voltage from one form to another by varying amplitude, frequency, or phase. It describes:
- Single-phase and three-phase AC-AC controllers that control output waveform through switching electronic power devices.
- Half-wave and full-wave phase control principles where the firing angle of thyristors controls power flow to the load.
- Equations to calculate output voltage, current, power factor for half-wave and full-wave controllers with resistive loads.
- Waveforms and operating principles of full-wave controllers, including discontinuous output and zero-average current when thyristors conduct equal times.
So in summary, it
1) DC-DC converters control the output voltage by converting the unregulated DC input voltage to a regulated DC output voltage. Switching regulators have near zero power loss by rapidly opening and closing a switch to transfer power from input to output in pulses.
2) A buck converter is a type of step-down DC-DC converter that produces an output voltage lower than the input voltage. It contains a switch, diode, and inductor. The inductor current ripples between a maximum and minimum value depending on the duty cycle of the switch.
3) Key parameters in buck converter design include duty cycle, switching frequency, inductor value, and capacitor value. These are selected to achieve the desired output voltage
This document summarizes inverters, which convert DC power to AC power by switching the DC input voltage in a predetermined sequence. It describes various types of inverters including single-phase half-bridge and full-bridge inverters, three-phase inverters, and discusses Fourier analysis of inverter output waveforms. Key concepts covered include the generation of output voltages from DC inputs, harmonic analysis using Fourier series, total harmonic distortion, and pulse-width modulation techniques for improving output waveform quality.
This document describes single-phase and three-phase half-wave and full-wave controlled rectifier circuits. It discusses the operation of these circuits, including which thyristors are conducting during different periods of the input voltage cycle. Key waveforms like input voltage, output voltage, and load current are shown. Equations are provided for calculating average and RMS output voltage and current values for different circuit configurations. Examples are given to demonstrate how to determine performance metrics like efficiency and voltage/current ratings for a single-phase full-wave converter with an RL load.
This chapter discusses uncontrolled rectifiers, which convert AC to DC. It describes single-phase half-wave and full-wave rectifiers, as well as three-phase bridge rectifiers. Key performance parameters for rectifiers are defined, including efficiency, form factor, ripple factor, and power factor. Operation of a half-wave rectifier with resistive and inductive loads is examined. Application of rectifiers to battery chargers is also discussed.
Chapter 1 Introduction to power Electronic Devices.pdfLiewChiaPing
The document provides an introduction to power electronics. It discusses power electronic systems and various types of electronic converters including AC-DC, DC-DC, DC-AC, and AC-AC converters. It also describes common power semiconductor devices such as power diodes, thyristors, MOSFETs, IGBTs, and IGCTs. Applications of power electronics in areas like power supplies, motor drives, renewable energy and power transmission are also highlighted. Gate drive circuits, switching losses, and heat dissipation in power switches are some other topics covered in the document.
This document discusses overcurrent protection methods used in power systems, including reclosers, fuses, and directional relays. It provides examples of how reclosers and fuses can clear temporary and permanent faults on a distribution feeder. It also explains how directional relays work by only tripping circuit breakers when current flows in the forward direction, allowing protection of systems with multiple power sources where faults may be fed from either direction. Directional relays are necessary in these two-source systems since overcurrent relays cannot be properly coordinated.
This document discusses overcurrent protection and radial system protection. It describes different types of overcurrent relays, including instantaneous and time-delay relays. Instantaneous relays trip immediately when current exceeds the pickup setting, while time-delay relays introduce an intentional delay based on how many times the pickup current is exceeded. The document includes examples of selecting settings for time-delay relays in a radial power system to coordinate protection among circuit breakers while maintaining a minimum coordination time interval between devices.
Here are the key steps and settings for the distance relay protection of the transmission line:
- Zone 1 reach is set to 80% of Line 1-2 impedance for fast tripping of faults close to the relay location.
- Zone 2 reach is set to 120% of Line 1-2 impedance to cover faults beyond the far end of Line 1-2 up to Bus 2.
- Zone 3 reach covers 100% of Line 1-2 plus 120% of the longer of Lines 2-3 and 2-4 to coordinate with downstream relays.
The settings determined for zones 1, 2 and 3 are 4.05∠80.9°Ω, 6.08∠80.9
This document discusses distance protection in power systems. It begins by introducing system protection and explaining why it is needed to protect systems from short circuits. It then describes the typical components of a protection system including instrument transformers, relays, and circuit breakers. Current transformers and voltage transformers are explained in detail, including their purposes, characteristics, and how they are used to scale down high voltages and currents for relay operation. Examples are provided to demonstrate how to evaluate current transformer performance.
BEF43303_-_201620171_W8 Power System Stability.pdfLiewChiaPing
This document discusses power system stability analysis and protection. Section 8.1 applies the equal-area criterion to determine stability limits for a sudden increase in power input. The maximum additional power that can be applied without losing stability is found by ensuring the accelerating and decelerating energy areas are equal. Section 8.2 applies the same technique to determine critical clearing times and angles for temporary three-phase faults on transmission lines connecting a generator to an infinite bus. The power-angle curve shifts during a fault, and stability is lost if the angle increases too much before fault clearing. Examples calculate critical clearing parameters for specific generator and line configurations.
BEF43303_-_201620171_W7 Power System Stability.pdfLiewChiaPing
This document provides an overview of power system stability analysis and the transient stability equal area criterion. It introduces steady-state and transient stability, defines the swing equation that describes the relative motion of a generator rotor during a disturbance, and presents synchronous machine models used for stability studies. It also explains the equal area criterion method for determining transient stability of a single machine connected to an infinite bus system by equating the accelerating and decelerating energy areas on the generator's power-angle curve.
BEF43303_-_201620171_W6 Analysis of Fault.pdfLiewChiaPing
This document discusses the analysis of balanced and unbalanced faults in power systems. It covers the modeling and calculation of fault currents for single line-to-ground, line-to-line, and double line-to-ground faults using symmetrical components. Equivalent circuits are presented for each type of fault. An example problem is also given to calculate fault currents for different fault types using given system data and a simple one-line diagram.
BEF43303_-_201620171_W5 Analysis of fault.pdfLiewChiaPing
The document discusses sequence impedances and fault analysis of power systems. It covers:
- Sequence impedances of equipment like loads, transmission lines, synchronous machines and transformers.
- How to derive the positive, negative and zero sequence impedance matrices.
- Representing the system using sequence networks that allow independent analysis of each sequence.
- Examples of analyzing single line to ground, line to line and other faults using the sequence impedance approach. Diagrams of sequence networks are provided for different fault conditions.
BEF43303_-_201620171_W4 Analysis of Balance and Unbalance Fault.pdfLiewChiaPing
This document discusses the analysis of balanced and unbalanced faults in power systems. It introduces balanced three-phase faults and various types of unbalanced faults. The key aspects covered include:
- Determining bus voltages and line currents during different fault types for protection and rating equipment.
- Generator behavior during sub-transient, transient, and steady-state periods of a fault.
- Calculating fault current, bus voltages, and line currents using bus impedance matrix methods for examples of three-phase faults on different buses.
- Definitions and calculations related to short-circuit capacity and symmetrical components analysis for unbalanced faults.
BEF43303 - 201620171 W3 Power Flow Analysis.pdfLiewChiaPing
The document describes power flow analysis and the Gauss-Seidel method for solving power flows. It discusses:
1) Power flow equations relating voltage, current, real and reactive power at each bus.
2) The Gauss-Seidel method iteratively solves these nonlinear equations to determine voltage phasors and power flows.
3) Line flows and losses are then calculated using the bus voltages and currents based on admittance matrices.
Examples and tutorials demonstrate applying the method to simple systems.
THE SACRIFICE HOW PRO-PALESTINE PROTESTS STUDENTS ARE SACRIFICING TO CHANGE T...indexPub
The recent surge in pro-Palestine student activism has prompted significant responses from universities, ranging from negotiations and divestment commitments to increased transparency about investments in companies supporting the war on Gaza. This activism has led to the cessation of student encampments but also highlighted the substantial sacrifices made by students, including academic disruptions and personal risks. The primary drivers of these protests are poor university administration, lack of transparency, and inadequate communication between officials and students. This study examines the profound emotional, psychological, and professional impacts on students engaged in pro-Palestine protests, focusing on Generation Z's (Gen-Z) activism dynamics. This paper explores the significant sacrifices made by these students and even the professors supporting the pro-Palestine movement, with a focus on recent global movements. Through an in-depth analysis of printed and electronic media, the study examines the impacts of these sacrifices on the academic and personal lives of those involved. The paper highlights examples from various universities, demonstrating student activism's long-term and short-term effects, including disciplinary actions, social backlash, and career implications. The researchers also explore the broader implications of student sacrifices. The findings reveal that these sacrifices are driven by a profound commitment to justice and human rights, and are influenced by the increasing availability of information, peer interactions, and personal convictions. The study also discusses the broader implications of this activism, comparing it to historical precedents and assessing its potential to influence policy and public opinion. The emotional and psychological toll on student activists is significant, but their sense of purpose and community support mitigates some of these challenges. However, the researchers call for acknowledging the broader Impact of these sacrifices on the future global movement of FreePalestine.
How Barcodes Can Be Leveraged Within Odoo 17Celine George
In this presentation, we will explore how barcodes can be leveraged within Odoo 17 to streamline our manufacturing processes. We will cover the configuration steps, how to utilize barcodes in different manufacturing scenarios, and the overall benefits of implementing this technology.
This presentation was provided by Rebecca Benner, Ph.D., of the American Society of Anesthesiologists, for the second session of NISO's 2024 Training Series "DEIA in the Scholarly Landscape." Session Two: 'Expanding Pathways to Publishing Careers,' was held June 13, 2024.
Temple of Asclepius in Thrace. Excavation resultsKrassimira Luka
The temple and the sanctuary around were dedicated to Asklepios Zmidrenus. This name has been known since 1875 when an inscription dedicated to him was discovered in Rome. The inscription is dated in 227 AD and was left by soldiers originating from the city of Philippopolis (modern Plovdiv).
Leveraging Generative AI to Drive Nonprofit InnovationTechSoup
In this webinar, participants learned how to utilize Generative AI to streamline operations and elevate member engagement. Amazon Web Service experts provided a customer specific use cases and dived into low/no-code tools that are quick and easy to deploy through Amazon Web Service (AWS.)
Elevate Your Nonprofit's Online Presence_ A Guide to Effective SEO Strategies...TechSoup
Whether you're new to SEO or looking to refine your existing strategies, this webinar will provide you with actionable insights and practical tips to elevate your nonprofit's online presence.
3. d
Introduction
• Short circuit occur when equipment
insulation fails due to system overvoltages
caused by:
caused by:
– Lightning or switching surges
• Flashover line-line (caused by wind)
• Flashover to tree
• Flashover to tree
– Insulation contamination by dirt/salt
– Mechanical failure
Cable insulation failure
• Cable insulation failure
– Natural causes
• Tower/pole or conductor falls
• Objects fall on conductors
• Objects fall on conductors
4. d
Introduction
• Short circuit currents can be several orders
of magnitude larger than normal operating
currents
currents
• If it is allowed to persist, may cause:
– Damage to the equipment due to heavy currents
Damage to the equipment due to heavy currents,
unbalanced current, or low voltage produces by
the short circuit
Fire and explosion effect equipment/people
– Fire and explosion effect equipment/people
– Disruption of service in the entire power system
area
5. d
Introduction
• Careful design, operation and
maintenance of system protection can
y p
minimize the occurrence of short
circuit but cannot eliminate them.
7. f
Function of System Protection
• Why do we need system protection:
– Detect fault
Detect fault
– Isolate faulted component
– Restore faulted component
Restore faulted component
• Aims:
Continued supply for rest of system
– Continued supply for rest of system
– Protect faulted part from damage
8. f
Types of Protection
A – Fuses
• For LV Systems, Distribution Feeders and
Transformers VT’s Auxiliary Supplies
Transformers, VT’s, Auxiliary Supplies
B - Over current and earth fault
B Over current and earth fault
• Widely used in All Power Systems
– Non-Directional
– Directional
9. f
Types of Protection
C - Differential
• For Distribution Feeders, Busbars,
Transformers Generators etc
Transformers, Generators etc
10. f
Types of Protection
D - Distance
• For Transmission and Sub-transmission Lines
and Distribution Feeders
and Distribution Feeders,
• Also used as back-up protection for
transformers and generators without
g
signaling/with signaling to provide unit
protection e.g.:
– Time-stepped distance protection
Time stepped distance protection
– Phase comparison for transmission lines
– Directional comparison for transmission lines
11. f
Types of Protection
E - Miscellaneous:
• Under and over voltage
Under and over voltage
• Under and over frequency
• A special relay for generators transformers
• A special relay for generators, transformers,
motors etc.
• Control relays: auto-reclose, tap change
Control relays: auto reclose, tap change
control, etc.
• Tripping and auxiliary relays
pp g y y
13. Design Criteria/Characteristics
• Reliability
– Operate dependably and in healthy operating
condition when fault conditions occur, even after
condition when fault conditions occur, even after
remaining idle for months or years.
• Selectivity
Clearly discriminate between normal and
– Clearly discriminate between normal and
abnormal system condition to avoid unnecessary,
false trips.
• Sensitivity
• Sensitivity
– Ability to distinguish the fault condition,
although the different between fault and normal
condition is small
condition is small.
14. Design Criteria/Characteristics
• Speed
– Fault at any point in the system must be
detected and isolated rapidly to minimize fault
detected and isolated rapidly to minimize fault
duration and equipment damage. Any intentional
time delays should be precise.
• Economy
Economy
– Provide maximum protection at minimum cost
• Simplicity
– Minimize protection equipment and circuitry
15. Economic Factor
• Total cost should take account of :
– Relays, schemes and associated panels and panel wiring
Relays, schemes and associated panels and panel wiring
– Setting studies
– Commissioning
– CTs and VTs
– Maintenance and repairs to relays
– Damage repair if protection fails to operate
– Lost revenue if protection operates unnecessarily
16. Economic Factor
• The cost of protection is equivalent to an insurance
policy against damage to plant, and loss of supply
and customer goodwill.
• Acceptable cost is based on a balance of economics
p
and technical factors. Cost of protection should be
balanced against the cost of potential hazards.
g p
• There is an economic limit on what can be spent.
• MINIMUM COST :Must ensure that all faulty
• MINIMUM COST :Must ensure that all faulty
equipment is isolated by protection.
18. System Protection Components
System Protection Components
Function:
• Transducers/Instrument Transformers (PT/VT & CT)
– Provide low current and voltage, standardized levels
suitable for the relays operation.
y p
• Relays
– Discriminate between normal operating and fault
conditions.
conditions.
– When current exceed a specified value, relay will be
operated and cause the trip coil of CB to be
energized/open their contact.
• Circuit Breakers
– Open the line, isolate the fault portion from the rest of the
system
y
21. l
System Protection Flow
voltage or current rise from normal condition
voltage or current rise from normal condition
voltage/current is reduced to match with relay rating
ti t i it b k
activate circuit breaker
circuit isolation
Relay
Transducer
Fault
Occur
Circuit
Breaker
Fault
Clear
22. I’ d ifi d l
I’ exceeds a specified value
O i il h NO
I’I’
Operating coil causes the NO
contacts to close
Trip coil of CB is energized (by
relay operation @ manually)
CB open
23. f
Zones of Protection
• For fault anyway within the zone, the
protection system responsible to
p y p
isolate everything within the zone from
the rest of the system.
y
• Isolation done by CB
• Must isolate only the faulty equipment
• Must isolate only the faulty equipment
or section
24. f
Zones of Protection
• Zones are defined for:
– Generators
Generators
– Transformers
– Buses
Buses
– Transmission and distribution lines
– Motors
– Motors
26. f
Zones of Protection
• 3 main characteristics:
– Zones are overlapped.
Zones are overlapped.
– Circuit breakers are located in the overlap
regions.
g
– For a fault anywhere in a zone, all circuit
breakers in that zone open to isolate the
fault.
27. l d f
Overlapped of Protection
• No blind spot:
– Neighboring zones are overlapped to avoid
Neighboring zones are overlapped to avoid
the possibility of unprotected areas
• Use overlapping CBs:
Use overlapping CBs:
– Isolation done by CB. Thus, it must be
inserted in each overlap region to identify
se ted eac ove lap eg o to de t y
the boundary of protective zones.
28. k
Primary & Back-up Protection
• Primary protection is the protection
provided by each zone to its elements.
p y
• However, some component of a zone
protection scheme fail to operate
protection scheme fail to operate.
• Back-up protection is provided which
take over only in the event of primary
take over only in the event of primary
protection failure.
29. l
Example
a) Consider the power system shown below, with the
generating source beyond buses 1, 3 and 4. What
are the zones of protection in which the system
are the zones of protection in which the system
should be divided? Which circuit breakers will open
for faults at P1 and P2?
1
2
3
P1 P
A C
P1
B
P2
A C
4
B
30. Fault at P1 = A, B, C
Fault at P2 = A, B, C,D, E
2 , , , ,
31. l
Example
a) If three circuits breakers are added at the tap
point 2, how would the zones of protection be
modified? Which circuit breakers will operate for
modified? Which circuit breakers will operate for
fault at P1 and P2 under these conditions?
1 3
2
P1 P2
A C
B
4
35. Zone Discrimination
• A system as shown with relays and breakers marked.
A single fa lt has res lted in the operation of
A single fault has resulted in the operation of
breakers B1, B2, B3 and B4.Identify the location of
the fault
Answer:
• Answer:
– Fault in the overlap zone at breaker B2 as shown
36. Discrimination
A t ti t t b bl t
• A protection system must be able to
discriminate between healthy and
f lt i t i it
faulty equipment or circuits.
• Discrimination can be achieved by
1. Current (Magnitude)
2. Time
2. Time
3. Comparison
37. d
Transducers
• Also known as Instrument Transformer
• Use to reduce abnormal current & voltage
l l d i i i l h
levels and transmit input signals to the
relays of a protection system.
• Why do we need transducer:
• Why do we need transducer:
– The lower level input to the relays ensures that
the physical hardware used to construct the
l ill b ll & h
relays will be small & cheap
– The personnel who work with the relays will be
working in a safe environment.
g
38. d
Transducers
• Current and Voltage Transformers
– Correct connection of CTs and VTs to the
Correct connection of CTs and VTs to the
protection is important directional,
distance, phase comparison and
differential protections.
– Earth CT and VT circuits at one point only;
40. l f
Voltage Transformers
• VT is considered to be sufficiently
accurate.
• It is generally modeled as an ideal
transformer
transformer.
• VT secondary connected to voltage-
sensing device with infinite
sensing device with infinite
impedance.
41. l f
Voltage Transformers
• Types of VTs
– Electromagnetic VT
– Capacitive VT
• Busbar VTs
S i l id i d d h d f li
– Special consideration needed when used for line
protection
• LV application(12 kV or lower)
• LV application(12 kV or lower)
– Industry standard – transformer with a primary
winding at a system voltage and secondary winding at
g y g y g
67 V(line-to-neutral) and 116 V(line-to-line).
46. l f
Voltage Transformers
HV and EHV
• Capacitor-coupled VT (CVT)
p p ( )
– C1 & C2 are adjusted, so that a few kVs of
voltage is obtains across C2
g 2
– Then, stepped down by T
• VTs must be fused or protected by MCB.
VTs must be fused or protected by MCB.
48. l f
Voltage Transformers
• VT ratios:
– ratio of the high voltage/secondary
ratio of the high voltage/secondary
voltage
1:1 2:1 2.5:1 4:1
5:1 20:1 40:1 60:1
80:1 100:1 200:1 300:1
80:1 100:1 200:1 300:1
400:1 600:1 800:1 1000:1
2000:1 3000:1 4500:1
2000:1 3000:1 4500:1
49. f
Current Transformers
• CT is an instrument transformer that is used
to supply a reduced value of current to
meters, protective relays, and other
instruments.
Th i i di i f i l
• The primary winding consist of a single turn
which is the power conductor itself.
CT d i t d t t
• CT secondary is connected to a current-
sensing device with zero impedance.
50. Function
Function
Isolate the high primary voltage of the system (main
Isolate the high primary voltage of the system (main
system) from the protection and measuring
equipment
Transform the high primary current of the circuit to a
small secondary current in the 1 – 5 Amp range
Example of CT ratio: 100/1, 200/1 100/5, 200/5, etc
If the primary current changes the secondary
current output will change accordingly For
current output will change accordingly. For
example, if 150 amps flow through the 300 amp
rated primary (300:5), the secondary current
p y ( ), y
output will be 2.5 amps.
51. Advantages:
Safety
provide electrical isolation from power system so that
personnel working with relays will work in a safer
personnel working with relays will work in a safer
environment
currents of 10 to 20 times (or greater) normal rating
often occur in CT windings for a few cycles during short
often occur in CT windings for a few cycles during short
circuit
Economy
Economy
lower input for relays ( smaller, simpler and less
expensive)
52. • Accuracy
– reading from measurement will be more
accurate since the range has been scaled
down.
– Because of their high degree of accuracy,
h CT i ll d b ili
these CTs are typically used by utility
companies for measuring usage for billing
purposes
purposes
53. Two main types
Two main types
Protection CT
Monitor operation of power grid
Monitor operation of power grid
not as accurate as Measuring CTs
for supplying current to protective relays.
The wider range of current allows the protective relay
The wider range of current allows the protective relay
to operate at different fault levels.
M i CT ( t i )
Measuring CT (metering)
are used where a high degree of accuracy is required
from low-load values up to full-load of a system.
An e ample : tili ed b tilit companies for large
An example : utilized by utility companies for large
capacity revenue billing.
54. f
Current Transformers
• CTs ratio(secondary current rating is 5A)
50:5 100:5 150:5 200:5
250:5 300:5 400:5 450:5
500:5 600:5 800:5 900:5
1000:5 1200:5
• CTs also available with the secondary rating
CTs also available with the secondary rating
of 1A
55. Current transformers used in metering equipment for 3 phase 400 ampere electricity supply
Shapes and sizes can vary depending on the
end user or switchgear manufacturer. Typical
examples of low voltage single ratio metering
examples of low voltage single ratio metering
current transformers are either ring type or
plastic moulded case. High-voltage current
transformers are mounted on porcelain
transformers are mounted on porcelain
bushings to insulate them from ground.
59. 4 Important Parameters on CT
R d i
• Rated primary current.
• Rated secondary current (usually in the 1 – 5 Amp range)
• Burden (in VA)
• Burden (in VA)
– max load can be connected to the secondary of the CT.
– Expressed in VA or impedance
p p
– CT is unloaded if the secondary winding is short‐circuited
(burden = 0 because voltage = 0)
• Accuracy class
– the error limits of the CT specified in the standard
specification (on the label or the nameplate of the CT)
specification (on the label or the nameplate of the CT)
– Eg: Protection CT – class 5P, 10P
60. Types of CT
Types of CT
1. Protection CT
divided into Class 5P or 10P
CT marked “5P20” indicates the composite error of 5%
which is applicable for current up to 20 times rated
which is applicable for current up to 20 times rated
current.
Special purpose of CT are designed as Class X
p p p g
Examples of Protection CT:
Instantaneous over current relays & trip coils : 2.5VA class 10P5
Thermal in erse time rela s :7 5VA Class 10P10
Thermal inverse time relays :7.5VA Class 10P10
Low consumption Relay : 2.5VA class 10P10
(IDMT) Over current : 15VA Class 10P10/15
IDMT th f lt l ith f lt t bilit t ti di
IDMT earth fault relays with fault stability or accurate time grading :
15VA 5P10
61. 2 Measuring CT
2. Measuring CT
Divided into accuracy classes 0.1, 0.2, 0.5, 1.0
Measuring CT with a specification 800/5 A 15 VA Class
Measuring CT with a specification 800/5 A, 15 VA, Class
0.5 means the rated primary current is 800 A, the
rated secondary current is 5A, the burden is 15 VA and
th t ti f 0 5% t th t d t
the current ratio error of 0.5% at the rated current
Accuracy Class Requirements:
0 1 or 0 2 for precision measurements
0.1 or 0.2 for precision measurements
0.5 for high grade kilowatt hour meters.
1.0 for commercial grade kilowatt hour meters
g
1 or 3 for general industrial measurements.
3 or 5 for approximate measurements
62. l
Example:
• Protection CT Class 5P
– Protection CT with a composite error of 5% for
current up to rated current
– A CT marked “5P20’ indicates that this is a
protection CT with a composite error of 5% for
protection CT with a composite error of 5% for
currents up to 20 times the rated current.
• Measuring CT Class 0.1
– Measuring CT has current ratio error of 0.1% for
g
currents between 100% to 120% of the rated
current.
63. CT Performance
CT Performance
A measuring CT has to be accurate from
above 10% to 120% of their rated current
above 10% to 120% of their rated current.
On the other hand a protection CT has to be
On the other hand, a protection CT has to be
accurate for currents well in excess of the
rated current i.e. at least 10 times the rated
current.
To provide the required accuracy the CT’s
To provide the required accuracy, the CT s
have to operate in the linear portion of the
magnetizing curve as shown in figure below;
64. CT Errors
hi i d b d hi h i ll l i h i i
•This error is due to burden which is parallel with excitation
impedance.
•A small value of input current is used to excite the core, thus,
p , ,
current flows to the burden is reduced.
Ip’ = Io’ + Is Ip = Io + Is’
Ip’ = Primary current referred secondary Ip = primary current
Io’ = excitation current referred to secondary Io = excitation current
Io excitation current referred to secondary Io excitation current
Is = secondary current Is’ = secondary current referred to primary.
65. Current ratio error (refer to sec)
( )
%
100
p
s
I
I
I
Where,
Kn rated transformer ratio
%
100
n
p
s
p
I
K
I
I
I Kn – rated transformer ratio
Ip ‐ actual primary current
Is ‐ actual secondary current
Current ratio error (refer to primary)
n
p
K
I when Ip is flowing
Current ratio error (refer to primary)
%
100
p
s
I
I
I
%
100
p
p
s
n
p
I
I
I
K
I
66. Example
p
In a 300/5A CT, the measured secondary current of a
primary current of 300 is 4.9 A. Calc the CT ratio error.
300
Solution
60
5
300
n
K
Refer to sec Refer to
%
100
p
n
p
s
I
K
I
I
error
ratio
Current
or %
100
p
s
n I
I
K
error
ratio
Current
Refer to sec
primary
%
2
%
100
60
300
60
300
9
.
4
n
p
K
or
%
2
%
100
300
300
)
9
.
4
(
60
%
100
p
I
error
ratio
Current
60
67. Example 2
p
Evaluate the performance & calculate the CT
error of a 100/5A CT for the following secondary
error of a 100/5A CT for the following secondary
output currents & burdens :
• Is = 5A , = 0.5Ω
• Is = 8A , = 0.8Ω
• Is = 15A , = 1.5Ω
Use excitation curve & secondary resistance for
Use excitation curve & secondary resistance for
multiratio CT
68.
69. Solution '
( ) 5 , 0.5
0 082 0 5
S B
Total eq B
a I A Z
Z Z Z
0.082 0.5
0.582
S S Total
E I Z
5 0.582
2.91
, ' 0.25
o
V
From the curve I A
F th t bl 100/5A CT
' '
o
P o s
I I I
0.25 5
5 25A
• From the table, 100/5A CT
has secondary resistance of
0.082Ω. Thus Zeq’= 0.082Ω
5.25
100
5.25
5
105
P
A
I
A
q
105
'
100%
'
s P
P
A
I I
current ratio error
I
5 5.25
100%
5.25
4.8%
71. ( ) 8 , 0.8
0.082 0.8
0 882
S B
Total
b I A Z
Z
0.882
8 0.882
S S Total
E I Z
8 0.882
7.06
, ' 0.4
o
V
From the curve I A
' 0.4 8
8.4
P
I
A
100
8.4
P
I
100
5
168A
'
100%
'
8 8 4
s P
P
I I
current ratio error
I
8 8.4
100%
8.4
4.8%
72. C) IS = 15A , ZS = 1.5Ω
Z = 0 082 + 1 5
ZTOTAL 0.082 + 1.5
= 1.582Ω
ES = IS X ZTOTAL
15 X 1 582
=15 X 1.582
= 23.73V
From the curve, IO’=20A
Conclusion:
O
IP’ = 20 + 15 = 35A
IP = 35 X 100/5
= 700A
Conclusion:
High CT saturation causes a
large CT error as in case( C ).
S d d i i l
700A
•Current ratio error =
%
1
57
%
100
35
15
Standard practice is to select a
CT ratio to give a little less
than 5A secondary current
%
1
.
57
%
100
35
y
(IS< 5A) at max normal load.
However, case (a) is still
suitable for a max primary load
suitable for a max primary load
current of about 100A
73. Example
p
• An over current relay set to operate at 8A is
connected to a 100/5A CT with Is = 8A. Will
the relay detect a 200A primary fault
current if the burden ZB
(a) 0.8 Ω
(b) 3.0 Ω
• Use excitation current curve and secondary
• Use excitation current curve and secondary
resistance table for multi‐ratio CT
74. Solution
Solution
I 8A ( t l tti )
• IS = 8A (overcurrent relay setting)
• IP = 200A (fault current), 100/5A CT , ZEQ’ = 0.082
V
Z
I
E
Z
Z
Z
A
I
b
eq
total
s
06
7
882
0
8
882
.
0
8
.
0
082
.
0
'
8
A
I
I
I
A
I
curve
the
from
V
Z
I
E
o
total
s
s
4
8
4
0
8
'
'
4
.
0
'
,
06
.
7
882
.
0
8
A
K
I
I
A
I
I
I
n
p
p
o
s
p
168
5
100
4
.
8
'
4
.
8
4
.
0
8
IP = 168A produces IS = 8A
– relay will operate
y p
So, if IP = 200A (>168A)
– relay will operate
75.
76. l d
Reclosers and Fuses
• Automatic reclosers are commonly used for
distribution circuit protection.
• Recloser: self-controlled device for automatically
• Recloser: self-controlled device for automatically
interrupting and reclosing an AC circuit with preset
sequence of openings and reclosures
Ha e b ilt in control to clear temporar fa lts and
• Have built-in control to clear temporary faults and
restores service with momentary outages.
• Disadvantages:
– increase hazard when circuit is physically contacted by
people.
– Recloser should be locked out during live-line maintenance.
77. l d
Reclosers and Fuses
1. An upstream fuse/relay
has detected a fault
2. Downstream system
isolated by fuse or
b k
breaker
3. Automatic re-closing
ft d l f l if
after delay successful if
fault not permanent
78. l
Relays
• Discriminate between normal operating
and fault conditions.
• Type of Relays
– Magnitude Relay
– Directional Relay
– Distance/Ratio Relay
– Differential Relay
– Pilot Relay
79. d l
Magnitude Relays
• Also called as Overcurrent Relay
• Response to the magnitude of input
quantities ie current
quantities ie. current.
• Energize CB trip coil when the fault current
magnitude exceeds a predetermined value or
i h i b i
trips when a current rises above a set point
(pick-up current).
• If it is less than the set point value, the relay
If it is less than the set point value, the relay
remains open, blocking the trip coil.
• Time-delay Overcurrent Relay also have the
same operating method but with an
same operating method but with an
intentional time-delay.
80. l l
Directional Relays
R d t f lt l i di ti
• Responds to fault only in one direction,
either to the left or to the right of its
location
location
• Operation depends upon the direction (lead
or lag) of the fault current with respect to a
reference voltage.
• The directional element of these relays
checks the phase angle between the current
checks the phase angle between the current
and voltage of one phase, and allows the
overcurrent unit to operate if this phase
p p
angle indicates current in the reverse
direction.
81. l
Ratio Relays
f l b h
• Operate for certain relations between the
magnitudes of voltage, current and the
phase angle between them
phase angle between them.
• Measures the distance between the relay
location and the point of fault in term of
location and the point of fault, in term of
impedance, reactance and admittance.
• Respond to the ratio of two phasor
• Respond to the ratio of two phasor
quantities as example Voltage and Current (Z
= V/R)
)
• Also called impedance or distance relay
82. ff l l
Differential Relays
• Respond to the vector difference between two
currents within the zone protection determined by
the location of CTs
the location of CTs.
• Not suitable for transmission-line protection
because the terminals of a line are separated by too
p y
great a distance to interconnect the CT secondaries.
• For the protection of generators, transformers,
buses
buses,
• Most differential-relay applications are of the
‘current-differential’ type.
yp
83. ff l l
Differential Relays
Relay
• Fault occur at X
• Suppose that current flows through the primary
circuit either to a load or to a short circuit located
at X.
• If the two current transformers have the same ratio,
and are properly connected, their secondary
currents will merely circulate between the two CTs
as sho n b the arro s and no c rrent ill flo
as shown by the arrows, and no current will flow
through the differential relay.
84. ff l l
R l
Differential Relays
Relay
• A flow on one side only, or even some current
flowing out of one side while a larger current
t th th id ill diff ti l
enters the other side, will cause a differential
current.
• In other words, the differential-relay current
y
will be proportional to the vector difference
between the currents entering and leaving the
protected circuit; and, if the differential
d h l ’ i k l h
current exceeds the relay’s pickup value, the
relay
85. ff l l
Differential Relays
Relay
• When a short circuit develop anywhere between
th t CT
the two CTs.
• If current flows to the short circuit from both
sides as shown, the sum of the CT secondary
currents will flow through the differential relay.
• It is not necessary that short-circuit current
flow to the fault from both sides to cause
secondary current to flow through the
differential relay.
86. l l
Pilot Relays
• The term ‘pilot’ means that between
the ends of the transmission line there
is an interconnecting channel of some
sort over which information can be
conveyed.
• Use communicated information from
• Use communicated information from
remote sites as input signals.
87. l l
Pilot Relays
• Transmitting fault signals from a
remote zone boundary to relays at the
terminals of a long TL
• Pilot relaying provides primary
protection only; back-up protection
must be provided by supplementary
relaying.
• Type : wire pilot, carrier-current pilot
Type : wire pilot, carrier current pilot
and microwave pilot.
88. l l
Pilot Relays
ZA
Z
• Station 1 consist of meter for reading
lt t d f t
ZB
voltage, current and power factor.
• Distance relay, tell the different between
fault at A (middle) and B (end) by knowing
fault at A (middle) and B (end) by knowing
the impedance characteristic per unit length
of the line
of the line.
89. l l
Pilot Relays
• Could not possibly distinguish between fault
B and C because impedance would be so
B and C because impedance would be so
small- Mistake in tripping CB for fault B or C
• Solution- indication from station B, when the
,
phase angle of the current at S-B(with
respect to current A) is different by
approximately 180o from it value for fault in
the line section AB.
90. l l
Pilot Relays
1 2
1
B C
A
(with respect to current A) is
different by approximately 180o
from it value for fault in the line
section
(with respect to current A) is
(with respect to current A) is
not different in degree from it
value for fault in the line
section