The document discusses grounding systems and safety practices. It defines different types of grounding including system grounding and equipment grounding. System grounding connects the electrical system to the earth and provides protection from lightning strikes, but does little to minimize fault currents. Equipment grounding connects enclosures to earth, but can increase the fault voltage to dangerous levels. The safest approach uses both a grounding system and a low-impedance fault return conductor connected to the electrical source to rapidly clear faults and minimize the magnitude and duration of fault currents. Parallel paths through building steel and conduits can further improve safety by reducing the effective fault impedance.
This document summarizes key parts of Chapter 41 (Protection Against Electric Shock) from the 17th Edition IEE Wiring Regulations Part 4. It outlines the different protective measures covered in this chapter, including automatic disconnection of supply, double/reinforced insulation, electrical separation, extra low voltage from SELV or PELV, additional protection, basic protection, obstacles and placing out of reach, and protective measures for installations controlled by skilled persons. The document provides brief descriptions and section references for these various protective measures.
Design and Implementation of a Single Phase Earth Fault RelayIJSRED
This document describes the design and implementation of a single phase earth fault relay with an alarm system. The relay was designed using an embedded system to reduce components, keep the system simple and cost effective. It consists of current sensors on the phase and neutral lines, a microcontroller to monitor current levels, and an alarm and switch driver to isolate the system if an imbalance is detected, indicating an earth fault. The objectives are to detect earth faults, measure phase and neutral currents, and disconnect power on a fault. This type of relay provides protection for electrical equipment and humans from earth faults.
The document summarizes the key parts of IEE Wiring Regulations 17th Edition Part 6, which covers the initial inspection and testing of electrical installations. It outlines the requirements for inspecting, testing and certifying new electrical installations. The main points are:
- Chapter 61 covers initial verification through inspection and testing to ensure compliance with regulations
- Chapter 62 covers periodic inspection and testing of existing installations
- Chapter 63 discusses the certification and reporting requirements, including which forms should be used to document inspection results and certification of new and existing installations.
This document summarizes key requirements from Chapter 53-56 of the 17th Edition IEE Wiring Regulations relating to electrical installation protection, isolation, switching, control, monitoring and earthing. It covers requirements for devices like RCDs, overcurrent protection, isolation and switching, as well as earthing arrangements, protective conductors and equipotential bonding. Key topics include selection of protective device ratings, coordination of protection, emergency switching, isolation requirements and earthing of circuits with high leakage currents.
The document discusses lightning concepts, including:
1. How cloud-to-ground lightning occurs due to charge separation in clouds and the equalization of charge potential between clouds and the earth.
2. The sequence of events in a lightning strike, where stepped leaders from clouds meet upward streamers from the earth's surface to form a discharge path.
3. Conventional lightning protection systems are dependent on a low-impedance ground, but facility grounding systems are often poorly maintained and insufficient, limiting the effectiveness of passive and active protection devices.
4. A new solution is introduced to overcome the shortcomings of conventional systems and provide reliable protection against all forms of lightning damage.
The document summarizes Part 5 of the 17th Edition of the IEE Wiring Regulations, which consists of 6 chapters related to the selection and erection of wiring systems. Chapter 51 covers Common Rules, including general requirements for compliance with safety standards, identification of conductors, accessibility of equipment, and prevention of mutual interference. It addresses topics such as acceptable standards for electrical equipment, consideration of operational conditions and external influences, and labeling requirements.
Post Glover is a leading manufacturer of grounding solutions and dynamic braking resistors. They have over 130 years of combined industrial and utility experience. Their factory in Kentucky integrates computer-aided design and manufacturing with strong engineering capabilities. Their experienced sales and engineering team provides timely support and response. Post Glover designs and manufactures products in accordance with all applicable safety standards. They offer various grounding solutions including neutral grounding resistors and grounding transformers.
The document describes a LightningMat EPR Safety Mat, which is a portable mat that can mitigate hazards from earth potential rise (EPR) during lightning strikes or electrical faults. It discusses the mat's unique three-layer design that redistributes voltage gradients across its surface to protect people standing on it. The mat is flexible, lightweight, and can be rolled up for easy transport and installation. It has applications for workers in remote or outdoor environments and anyone near conductive infrastructure.
This document summarizes key parts of Chapter 41 (Protection Against Electric Shock) from the 17th Edition IEE Wiring Regulations Part 4. It outlines the different protective measures covered in this chapter, including automatic disconnection of supply, double/reinforced insulation, electrical separation, extra low voltage from SELV or PELV, additional protection, basic protection, obstacles and placing out of reach, and protective measures for installations controlled by skilled persons. The document provides brief descriptions and section references for these various protective measures.
Design and Implementation of a Single Phase Earth Fault RelayIJSRED
This document describes the design and implementation of a single phase earth fault relay with an alarm system. The relay was designed using an embedded system to reduce components, keep the system simple and cost effective. It consists of current sensors on the phase and neutral lines, a microcontroller to monitor current levels, and an alarm and switch driver to isolate the system if an imbalance is detected, indicating an earth fault. The objectives are to detect earth faults, measure phase and neutral currents, and disconnect power on a fault. This type of relay provides protection for electrical equipment and humans from earth faults.
The document summarizes the key parts of IEE Wiring Regulations 17th Edition Part 6, which covers the initial inspection and testing of electrical installations. It outlines the requirements for inspecting, testing and certifying new electrical installations. The main points are:
- Chapter 61 covers initial verification through inspection and testing to ensure compliance with regulations
- Chapter 62 covers periodic inspection and testing of existing installations
- Chapter 63 discusses the certification and reporting requirements, including which forms should be used to document inspection results and certification of new and existing installations.
This document summarizes key requirements from Chapter 53-56 of the 17th Edition IEE Wiring Regulations relating to electrical installation protection, isolation, switching, control, monitoring and earthing. It covers requirements for devices like RCDs, overcurrent protection, isolation and switching, as well as earthing arrangements, protective conductors and equipotential bonding. Key topics include selection of protective device ratings, coordination of protection, emergency switching, isolation requirements and earthing of circuits with high leakage currents.
The document discusses lightning concepts, including:
1. How cloud-to-ground lightning occurs due to charge separation in clouds and the equalization of charge potential between clouds and the earth.
2. The sequence of events in a lightning strike, where stepped leaders from clouds meet upward streamers from the earth's surface to form a discharge path.
3. Conventional lightning protection systems are dependent on a low-impedance ground, but facility grounding systems are often poorly maintained and insufficient, limiting the effectiveness of passive and active protection devices.
4. A new solution is introduced to overcome the shortcomings of conventional systems and provide reliable protection against all forms of lightning damage.
The document summarizes Part 5 of the 17th Edition of the IEE Wiring Regulations, which consists of 6 chapters related to the selection and erection of wiring systems. Chapter 51 covers Common Rules, including general requirements for compliance with safety standards, identification of conductors, accessibility of equipment, and prevention of mutual interference. It addresses topics such as acceptable standards for electrical equipment, consideration of operational conditions and external influences, and labeling requirements.
Post Glover is a leading manufacturer of grounding solutions and dynamic braking resistors. They have over 130 years of combined industrial and utility experience. Their factory in Kentucky integrates computer-aided design and manufacturing with strong engineering capabilities. Their experienced sales and engineering team provides timely support and response. Post Glover designs and manufactures products in accordance with all applicable safety standards. They offer various grounding solutions including neutral grounding resistors and grounding transformers.
The document describes a LightningMat EPR Safety Mat, which is a portable mat that can mitigate hazards from earth potential rise (EPR) during lightning strikes or electrical faults. It discusses the mat's unique three-layer design that redistributes voltage gradients across its surface to protect people standing on it. The mat is flexible, lightweight, and can be rolled up for easy transport and installation. It has applications for workers in remote or outdoor environments and anyone near conductive infrastructure.
The document summarizes chapters and sections from Part 5 of the IEE Wiring Regulations 17th Edition, which covers the selection and erection of wiring systems. It outlines the key topics and regulations covered in each section, including requirements for conductor cross-sectional areas, electrical connections, minimizing fire spread, proximity to other services, and maintainability. The sections describe regulations for proper wiring system installation and safety.
The document summarizes Chapter 44 of the IEE Wiring Regulations 17th Edition Part 4, which covers protection against voltage disturbances and electromagnetic disturbances. It discusses regulations for protecting low voltage installations from temporary overvoltages from faults, as well as protection against overvoltages from atmospheric or switching sources. It also addresses measures for protection against undervoltages.
Modeling and test validation of a 15 kV - 24 MVA superconducting fault curren...Franco Moriconi
High-power short-circuit test results and numerical simulations of a 15kV–24MVA distribution-class High Temperature Superconductor (HTS) Fault Current Limiters (FCL) are presented and compared in this paper. The FCL design was based on the nonlinear inductance model here described, and the device was tested at 13.1kV line-to-line voltage for prospective fault currents up to 23kArms, prior to its installation in the electric grid. Comparison between numerical simulations and fault test measurements show good agreement. Some simulations and field testing results are depicted. The FCL was energized in the Southern California Edison grid on March 9, 2009.
Overview of Grounding for Industrial and Commercial Power Systemsmichaeljmack
This document summarizes a presentation on grounding for industrial and commercial power systems. It begins with an overview of basic electrical concepts like voltage, current, capacitance, and transformers. It then discusses the two main functions of grounding: safety/protection and providing a common reference point. Key aspects of grounding systems are explained, including minimizing shock hazards and ensuring proper overcurrent protection. The document provides definitions of grounding terminology and discusses requirements for grounding separately derived systems and solidly grounded transformer secondaries.
Superconductor fault current limiters (SFCLs) provide an effective way to limit fault current in power systems. SFCLs use the properties of superconductors, which have virtually zero resistance below a critical temperature, current, and magnetic field. During a fault, the superconductor transitions to a normal resistive state, limiting the fault current. The two main types are resistive and inductive SFCLs. SFCLs offer benefits over traditional fault current limiting methods like faster response, shorter recovery times, and the ability to protect equipment without upgrades. They can be applied in the main transformer, feeder, or bus-tie positions in a power system.
This document discusses safety practices regarding earthing and protection in electrical installations. It notes that approximately 12 people die every day and 42% of total fires occur due to electrical sources in India. Proper earthing and use of protective devices is important for safety. Factors like lack of maintenance, supervision, knowledge and negligence can lead to accidents. The document discusses causes of arcing faults and lightning accidents. It emphasizes the importance of proper earthing for safety, maintenance of voltage levels, and operation of protection devices. Earthing reduces touch and step voltages to safe levels.
High voltages can cause overvoltage events that exceed the design limits of electrical systems. There are two main types of overvoltage: lightning overvoltage from natural sources, and switching overvoltage caused by changing loads on a system. Lightning overvoltage occurs when a lightning strike induces high voltage in a system. Switching overvoltage happens when large inductive or resistive loads are connected or disconnected, causing voltage spikes. Both types of overvoltage can damage equipment and should be controlled through various techniques like resistors, phase control, and reactors. Uncontrolled overvoltages present a danger, so protection methods are important for system reliability and safety.
This document provides an overview of electrical protection in mines and quarries, with reference to the forthcoming Australian Standard HB 119 "Mines and Quarries Electrical Protection". It discusses key principles of protection including having a primary and independent back-up protection system with complete coverage. Protection is important for safety and depends on factors like dependability, coverage, and speed of fault clearance. Specialized training is required for protection work. Standards like AS 2067 and AS 3000 contain basic protection requirements.
Over voltages can be caused by internal factors like switching operations or insulation failures, or external factors like lightning. Lightning arrestors protect equipment by diverting high voltage surges to ground. They break down temporarily during over voltages and regain insulation at normal voltages. Insulation coordination determines equipment insulation strength to withstand normal operating voltages and temporary over voltages based on factors like highest system frequency, temporary over voltages, and transient surges. Equipment is tested and rated with a basic insulation level to ensure it can withstand impulse voltages above that level.
This document describes an automated electrical protection system for domestic homes. The system aims to automatically detect faults, isolate the faulty circuit, and restore power. It uses current sensors to measure the difference between incoming and outgoing current on each circuit. If the difference exceeds 30mA, the system can locate the faulty circuit by identifying which circuit breaker is tripped. When the fault is isolated by turning off that circuit breaker, the system will automatically reset the earth leakage circuit breaker to restore power to the unaffected circuits, improving power reliability and continuity for appliances that require it.
Surge current protection using superconductor ppt maheshKuldeep Singh
This seminar discusses using superconductors for surge current protection. Superconductors conduct electricity with zero resistance below a critical temperature. They can be used as fault current limiters to protect power systems when faults occur. Two main types of superconductor fault current limiters are resistive and inductive. Superconductive fault current limiters offer advantages like safety, reliability, and extended equipment life. Future plans include developing three-phase limiters for testing on power grids this century. Superconductive fault current limiters have applications in transmission and distribution systems.
The document discusses requirements for electrical installations according to the IEE Wiring Regulations 17th Edition Part 4. It focuses on Chapter 43 which covers protection against overcurrent. The chapter contains 7 sections that describe how live conductors must be protected from overcurrent through automatic disconnection devices, the positioning and characteristics of protective devices, coordination between conductors and overload protection, and exceptions for when protection can be omitted.
This document discusses electrical faults in domestic buildings and the devices used to protect circuits. It introduces major faults like overcurrent and earth leakage. The protection devices discussed are the earth leakage circuit breaker (ELCB) and miniature circuit breaker (MCB). The document then describes an experimental setup and automatic system to restore power after faults by resetting the ELCB and detecting fault locations.
Transient voltages, also called surges or spikes, are momentary changes in voltage or current that occur over a short period of time, usually less than 1/60th of a second. They are generated by both external sources like lightning and utility switching and internal sources like motor starts and static discharge. Transients can travel through a facility's electrical system and affect electronic equipment, causing erratic operation, lock ups, premature failure or decreased efficiency. Effective transient voltage suppression equipment can significantly increase the life of electrical and electronic systems and provide a strong return on investment.
The electrical power system in offshore oil & gas installation, consists of a large
distribution network, generally operating in island mode i.e., without grid support. For a compact
utility plate form design, multiple gas turbine-generators without generator transformers, feed
directly to 11kV switchgear. Such a configuration however, introduces high capacitive charging
current (Ico), which is more than the preferred high resistance grounding of generator neutral
through 10A, 10sec resistor, to safeguard the generator core from damage during an earth fault.
Therefore, some utility prefers to select low resistance grounding to limit the fault current above
Ico; however this can cause severe damage to generator core. Generally, oil & gas installation is a
customized design. So, earthing scheme of 11kV generating utility system should be selected
judiciously at basic engineering stage to avoid equipment damage and protection mal-operation
during operation. Different methods of earthing scheme are available to mitigate the same. One of
the method is presented here in which generator neutral is connected to high resistance grounding
and 11kV switchgear connected to low resistance grounding though zig-zag transformer, subject to
single grounding operation at a time. Prior to synchronization or under complete load throw
scenario, generator circuit breaker is opened. So, an earth fault in generator or evacuation system,
create over-voltage or ferro-resonance conditions, stressing insulation of generator and associated
system. This is mitigated by putting neutral earthing resistor into service at generator neutral. This
paper presents the experience learned in designing neutral earthing scheme for off-shore utility
plant in view of high capacitive charging current at 11kV voltage level, outlines impact on stator
core damage, mitigation and conclusion
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
This document discusses unsymmetrical faults in power systems. It defines unsymmetrical faults as faults that give rise to unbalanced unsymmetrical fault currents and can occur in generators, transformers, and transmission lines. The document describes three types of unsymmetrical faults: single line to ground faults, line to line faults, and double line to ground faults. It also lists some common causes of faults, such as falling trees, wind and ice loading, vehicle collisions, birds shorting lines, and insulation failures.
This document discusses power quality issues related to wind power integration. It begins with an abstract noting how increasing electricity demand is leading to more renewable energy sources like wind power, but wind integration can negatively impact the grid's power quality. The document then covers international power quality standards, defines power quality, and lists various power quality issues caused by wind power like power imbalances, voltage variations, harmonics, and flickers. Challenges of wind power integration to power system stability are also discussed. Finally, the document presents some mitigation strategies for integrating wind energy conversion systems onto the grid.
The document discusses the concept of earthing in electric power system engineering. It defines earthing as connecting electrical equipment to the earth or ground for safety and proper system operation. There are two main types of earthing discussed: neutral or mains earthing, which connects the star point of power lines to ground; and equipment earthing, which grounds all non-current carrying metal parts. Solidly grounding the neutral point provides the best protection but causes high fault currents, while resistance or impedance earthing limits fault current but displaces voltages. The document recommends using chemical earthing rods for lower earth resistance and periodic inspection and testing of earthing systems to ensure safety.
This document discusses short-circuit currents in electrical power systems. It defines a short circuit as any accidental contact between points that normally have different voltages. Short-circuit currents are analyzed to adequately size protection devices, check circuit breaker capacities, and modify network structures. There are various types of short circuits, including phase-to-earth, phase-to-phase, and three-phase faults. Short circuits can damage insulation, weld conductors, and cause fires. They also cause voltage dips, instability, and loss of synchronization. Short-circuit currents contain subtransient, transient, and steady-state periods. Near-generator and far-generator faults result in different short-circuit current waveforms. Key quantities include
The document summarizes chapters and sections from Part 5 of the IEE Wiring Regulations 17th Edition, which covers the selection and erection of wiring systems. It outlines the key topics and regulations covered in each section, including requirements for conductor cross-sectional areas, electrical connections, minimizing fire spread, proximity to other services, and maintainability. The sections describe regulations for proper wiring system installation and safety.
The document summarizes Chapter 44 of the IEE Wiring Regulations 17th Edition Part 4, which covers protection against voltage disturbances and electromagnetic disturbances. It discusses regulations for protecting low voltage installations from temporary overvoltages from faults, as well as protection against overvoltages from atmospheric or switching sources. It also addresses measures for protection against undervoltages.
Modeling and test validation of a 15 kV - 24 MVA superconducting fault curren...Franco Moriconi
High-power short-circuit test results and numerical simulations of a 15kV–24MVA distribution-class High Temperature Superconductor (HTS) Fault Current Limiters (FCL) are presented and compared in this paper. The FCL design was based on the nonlinear inductance model here described, and the device was tested at 13.1kV line-to-line voltage for prospective fault currents up to 23kArms, prior to its installation in the electric grid. Comparison between numerical simulations and fault test measurements show good agreement. Some simulations and field testing results are depicted. The FCL was energized in the Southern California Edison grid on March 9, 2009.
Overview of Grounding for Industrial and Commercial Power Systemsmichaeljmack
This document summarizes a presentation on grounding for industrial and commercial power systems. It begins with an overview of basic electrical concepts like voltage, current, capacitance, and transformers. It then discusses the two main functions of grounding: safety/protection and providing a common reference point. Key aspects of grounding systems are explained, including minimizing shock hazards and ensuring proper overcurrent protection. The document provides definitions of grounding terminology and discusses requirements for grounding separately derived systems and solidly grounded transformer secondaries.
Superconductor fault current limiters (SFCLs) provide an effective way to limit fault current in power systems. SFCLs use the properties of superconductors, which have virtually zero resistance below a critical temperature, current, and magnetic field. During a fault, the superconductor transitions to a normal resistive state, limiting the fault current. The two main types are resistive and inductive SFCLs. SFCLs offer benefits over traditional fault current limiting methods like faster response, shorter recovery times, and the ability to protect equipment without upgrades. They can be applied in the main transformer, feeder, or bus-tie positions in a power system.
This document discusses safety practices regarding earthing and protection in electrical installations. It notes that approximately 12 people die every day and 42% of total fires occur due to electrical sources in India. Proper earthing and use of protective devices is important for safety. Factors like lack of maintenance, supervision, knowledge and negligence can lead to accidents. The document discusses causes of arcing faults and lightning accidents. It emphasizes the importance of proper earthing for safety, maintenance of voltage levels, and operation of protection devices. Earthing reduces touch and step voltages to safe levels.
High voltages can cause overvoltage events that exceed the design limits of electrical systems. There are two main types of overvoltage: lightning overvoltage from natural sources, and switching overvoltage caused by changing loads on a system. Lightning overvoltage occurs when a lightning strike induces high voltage in a system. Switching overvoltage happens when large inductive or resistive loads are connected or disconnected, causing voltage spikes. Both types of overvoltage can damage equipment and should be controlled through various techniques like resistors, phase control, and reactors. Uncontrolled overvoltages present a danger, so protection methods are important for system reliability and safety.
This document provides an overview of electrical protection in mines and quarries, with reference to the forthcoming Australian Standard HB 119 "Mines and Quarries Electrical Protection". It discusses key principles of protection including having a primary and independent back-up protection system with complete coverage. Protection is important for safety and depends on factors like dependability, coverage, and speed of fault clearance. Specialized training is required for protection work. Standards like AS 2067 and AS 3000 contain basic protection requirements.
Over voltages can be caused by internal factors like switching operations or insulation failures, or external factors like lightning. Lightning arrestors protect equipment by diverting high voltage surges to ground. They break down temporarily during over voltages and regain insulation at normal voltages. Insulation coordination determines equipment insulation strength to withstand normal operating voltages and temporary over voltages based on factors like highest system frequency, temporary over voltages, and transient surges. Equipment is tested and rated with a basic insulation level to ensure it can withstand impulse voltages above that level.
This document describes an automated electrical protection system for domestic homes. The system aims to automatically detect faults, isolate the faulty circuit, and restore power. It uses current sensors to measure the difference between incoming and outgoing current on each circuit. If the difference exceeds 30mA, the system can locate the faulty circuit by identifying which circuit breaker is tripped. When the fault is isolated by turning off that circuit breaker, the system will automatically reset the earth leakage circuit breaker to restore power to the unaffected circuits, improving power reliability and continuity for appliances that require it.
Surge current protection using superconductor ppt maheshKuldeep Singh
This seminar discusses using superconductors for surge current protection. Superconductors conduct electricity with zero resistance below a critical temperature. They can be used as fault current limiters to protect power systems when faults occur. Two main types of superconductor fault current limiters are resistive and inductive. Superconductive fault current limiters offer advantages like safety, reliability, and extended equipment life. Future plans include developing three-phase limiters for testing on power grids this century. Superconductive fault current limiters have applications in transmission and distribution systems.
The document discusses requirements for electrical installations according to the IEE Wiring Regulations 17th Edition Part 4. It focuses on Chapter 43 which covers protection against overcurrent. The chapter contains 7 sections that describe how live conductors must be protected from overcurrent through automatic disconnection devices, the positioning and characteristics of protective devices, coordination between conductors and overload protection, and exceptions for when protection can be omitted.
This document discusses electrical faults in domestic buildings and the devices used to protect circuits. It introduces major faults like overcurrent and earth leakage. The protection devices discussed are the earth leakage circuit breaker (ELCB) and miniature circuit breaker (MCB). The document then describes an experimental setup and automatic system to restore power after faults by resetting the ELCB and detecting fault locations.
Transient voltages, also called surges or spikes, are momentary changes in voltage or current that occur over a short period of time, usually less than 1/60th of a second. They are generated by both external sources like lightning and utility switching and internal sources like motor starts and static discharge. Transients can travel through a facility's electrical system and affect electronic equipment, causing erratic operation, lock ups, premature failure or decreased efficiency. Effective transient voltage suppression equipment can significantly increase the life of electrical and electronic systems and provide a strong return on investment.
The electrical power system in offshore oil & gas installation, consists of a large
distribution network, generally operating in island mode i.e., without grid support. For a compact
utility plate form design, multiple gas turbine-generators without generator transformers, feed
directly to 11kV switchgear. Such a configuration however, introduces high capacitive charging
current (Ico), which is more than the preferred high resistance grounding of generator neutral
through 10A, 10sec resistor, to safeguard the generator core from damage during an earth fault.
Therefore, some utility prefers to select low resistance grounding to limit the fault current above
Ico; however this can cause severe damage to generator core. Generally, oil & gas installation is a
customized design. So, earthing scheme of 11kV generating utility system should be selected
judiciously at basic engineering stage to avoid equipment damage and protection mal-operation
during operation. Different methods of earthing scheme are available to mitigate the same. One of
the method is presented here in which generator neutral is connected to high resistance grounding
and 11kV switchgear connected to low resistance grounding though zig-zag transformer, subject to
single grounding operation at a time. Prior to synchronization or under complete load throw
scenario, generator circuit breaker is opened. So, an earth fault in generator or evacuation system,
create over-voltage or ferro-resonance conditions, stressing insulation of generator and associated
system. This is mitigated by putting neutral earthing resistor into service at generator neutral. This
paper presents the experience learned in designing neutral earthing scheme for off-shore utility
plant in view of high capacitive charging current at 11kV voltage level, outlines impact on stator
core damage, mitigation and conclusion
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
This document discusses unsymmetrical faults in power systems. It defines unsymmetrical faults as faults that give rise to unbalanced unsymmetrical fault currents and can occur in generators, transformers, and transmission lines. The document describes three types of unsymmetrical faults: single line to ground faults, line to line faults, and double line to ground faults. It also lists some common causes of faults, such as falling trees, wind and ice loading, vehicle collisions, birds shorting lines, and insulation failures.
This document discusses power quality issues related to wind power integration. It begins with an abstract noting how increasing electricity demand is leading to more renewable energy sources like wind power, but wind integration can negatively impact the grid's power quality. The document then covers international power quality standards, defines power quality, and lists various power quality issues caused by wind power like power imbalances, voltage variations, harmonics, and flickers. Challenges of wind power integration to power system stability are also discussed. Finally, the document presents some mitigation strategies for integrating wind energy conversion systems onto the grid.
The document discusses the concept of earthing in electric power system engineering. It defines earthing as connecting electrical equipment to the earth or ground for safety and proper system operation. There are two main types of earthing discussed: neutral or mains earthing, which connects the star point of power lines to ground; and equipment earthing, which grounds all non-current carrying metal parts. Solidly grounding the neutral point provides the best protection but causes high fault currents, while resistance or impedance earthing limits fault current but displaces voltages. The document recommends using chemical earthing rods for lower earth resistance and periodic inspection and testing of earthing systems to ensure safety.
This document discusses short-circuit currents in electrical power systems. It defines a short circuit as any accidental contact between points that normally have different voltages. Short-circuit currents are analyzed to adequately size protection devices, check circuit breaker capacities, and modify network structures. There are various types of short circuits, including phase-to-earth, phase-to-phase, and three-phase faults. Short circuits can damage insulation, weld conductors, and cause fires. They also cause voltage dips, instability, and loss of synchronization. Short-circuit currents contain subtransient, transient, and steady-state periods. Near-generator and far-generator faults result in different short-circuit current waveforms. Key quantities include
The document discusses short circuits (faults) in electrical systems. It defines a short circuit as a low resistance path allowing current to flow along an unintended path. Short circuits can damage equipment and endanger safety if fault currents exceed ratings. The document then provides details on types of short circuits including shunt faults like line-to-ground and line-to-line, and series faults like open circuits. Short circuit studies are important to ensure protection devices and equipment can withstand fault currents.
This document discusses symmetrical and unsymmetrical faults in electric power systems. It begins with an introduction that defines faults and their causes. It then discusses different types of faults including symmetrical three-phase faults and unsymmetrical single line-to-ground faults. The key factors that determine fault current magnitudes are also outlined. Transient and subtransient reactances are defined and their use in calculating short circuit currents is explained. Percentage resistance and reactance are also defined. The chapter then goes into more detail about analyzing symmetrical three-phase faults on both unloaded and loaded generators. An example fault calculation is also included.
PROTECTION AGAINST OVER VOLTAGE AND GROUNDING Part 2Dr. Rohit Babu
- The document discusses grounded and ungrounded neutral systems in power systems.
- In an ungrounded system, the neutral is isolated from ground which can cause overvoltages and issues with fault detection.
- Grounded systems connect the neutral to ground to limit voltages and improve safety, reliability and fault detection.
- Common methods for grounding the neutral include solid grounding, resistance grounding, reactance grounding and Peterson coil grounding. The selection depends on system size and protection requirements.
PROTECTION AGAINST OVER VOLTAGE AND GROUNDINGDr. Rohit Babu
- The document discusses grounded and ungrounded neutral systems in power systems.
- In an ungrounded system, the neutral is isolated from ground which can cause overvoltages and issues with fault detection.
- Grounded systems connect the neutral to ground to limit voltages and improve safety, reliability and fault detection.
- Common methods for grounding the neutral include solid grounding, resistance grounding, reactance grounding and Peterson coil grounding. The selection depends on system size and protection requirements.
The document describes a project report on three phase fault analysis with auto reset. It includes a block diagram of the project, descriptions of the hardware components used including transformers, voltage regulators, 555 timers, and relays. It also includes schematic and layout diagrams and details on testing the hardware. The system is designed to automatically disconnect the three phase power supply in the event of a fault, with the supply automatically resetting for temporary faults but remaining tripped for permanent faults.
This document discusses power quality issues related to wind power integration. It begins with an abstract noting how increasing electricity demand is leading to more renewable energy sources like wind power, but wind farm integration can negatively impact the grid's power quality. The document then covers international power quality standards, defines power quality issues, and lists various causes of power quality problems like power imbalances, voltage variations, harmonics, and flickers that can result from wind power integration. Finally, it discusses challenges wind power poses to grid stability and provides mitigation strategies like improved energy storage, forecasting, and grid reinforcement.
The document discusses power quality issues related to solar cells and inverters. It provides information on standards for power quality parameters like harmonics, voltage variations, sags and swells. The document outlines the operation of solar cells and photovoltaic cells, and discusses factors that affect their efficiency. It also summarizes Indian manufacturing guidelines for solar cells and describes different types of inverters used in photovoltaic systems.
Concept and Viability of High Temperature Superconductor Fault Current Limite...IOSR Journals
This document discusses the concept and viability of using a high temperature superconductor fault current limiter (HTSFCL) for power system protection. It begins with an introduction to the increasing fault current levels in power systems due to rising loads. It then reviews previous fault current limiting methods and outlines the ideal characteristics of a fault current limiter. The document focuses on modeling and simulating an HTSFCL using MATLAB. The HTSFCL design incorporates superconducting and stainless steel layers. Simulation results show the HTSFCL's ability to limit fault currents within a cycle by transitioning from a superconducting to resistive state as temperature rises during a fault.
This document discusses different methods of grounding electrical systems, including solid grounding, resistance grounding, reactance grounding, and resonant groundings using a Peterson coil. Solid grounding directly connects the neutral point to earth, holding it at earth potential but allowing high fault currents. Resistance grounding limits fault current by connecting through a resistor. Reactance grounding uses an inductor instead of resistor. Resonant grounding with a Peterson coil adjusts the inductance to balance capacitive currents and prevent arcing faults.
The document provides information on electrical safety practices related to power distribution systems. It discusses hazards like electrocution and electrical fires that occur daily due to unsafe electrical installations. It emphasizes the importance of following safety procedures during electrical work and mentions common accident causes like improper tools, lack of protective devices, or poor supervision. The document also contains technical details on electrical topics like arcing faults, earthing systems, surge arrestors, and substation design standards to help ensure safe and reliable power distribution.
1) Neutral grounding is the process of connecting the neutral point of a 3-phase system to earth to provide protection. There are several methods including solid grounding, resistance grounding, and reactance grounding.
2) Solid grounding directly connects the neutral to earth but can cause high fault currents. Resistance grounding limits fault current by connecting through a resistor.
3) Neutral grounding provides protection from earth faults by allowing fault currents to operate protective devices and isolate faults. It also improves safety, reliability, and reduces over voltages.
How Earthing works. What is earthing all in one for students and others? Types of Earthing. description that is needed. You can get to know how important Earthing is.
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1. STUDY ON GROUNDING SYSTEM AND
SAFETY PRACTICES
MOHAMMED FAIZ M
S7 EE
ROLL NO. 25
DEPARTMENT OF ELECTRICALAND ELECTRONICS
COLLEGE OF ENGINEERING KIDANGOOR
5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 1
2. CONTENTS
1. INTRODUCTION
2. EFFECT OF ELECTRIC FAULT CURRENT
3. TYPES OF GROUNDING
4. FAULT RETURN CONDUCTOR
5. METHODS OF SENSING AND CLEARING A FAULT TO EQUIPMENT
6. OTHER PATHWAYS
7. CONCLUSIONS
8. REFERENCES
5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 2
3. INTRODUCTION
Grounding, generally means providing a connection from one conductor of the
system to an electrode that is buried in the earth.
Grounding is generally accepted as an operation to make systems safe.
The fault return conductor brings the potential at equipment enclosures to ground
but only when there is no fault current.
The potential rise due to the fault current flow can raise the potential to a
hazardous level.
Simple grounding does not provide for safe systems.
5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 3
4. The fault return conductor and the overcurrent protective device, in combination,
may prevent ventricular fibrillation and provide safer systems.
Grounding or connection to earth, is an action to minimise the consequence on
electrical faults.
If the enclosure is at earth potential and an individual is in contact with the earth,
there will be no difference in the potential to result in a shock.
For a fault current flows in the connection to the earth, the enclosure is raised in
potential equal to the product of the fault current and the impedance to the earth.
Now there will be a difference of potential between the enclosure and the body in
contact with the earth, and a shock potential is established.
5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 4
INTRODUCTION(Contd… )
5. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 5
Non-normal electric current flow results in electric shock and fire.
Fires are started by raising the temperature of a combustible material above its
ignition point.
The power generated by a current flowing through a resistive element is
determined by the i2R function.
The power dissipated in the resistive element can raise the temperature.
Minimizing the total time that the fault current flows will minimize the total energy
developed.
INTRODUCTION(Contd… )
6. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 6
EFFECTS OF ELECTRIC FAULT
CURRENT
The effects of an electric current through the body (1000ohm) from 5 to 95
percentile have been measured as follows (independent of time):
Threshold of feeling: 1 mA
Let-go current: 6-14 mA for women and 9-22 mA for men
Arrest respiration: 20 - 40 mA across chest.
Thus, maximum fault voltage of 6 V is desirable.
Obtaining this low level of fault voltage may not be practical.
The two factors which defines the level of safety of an electrical system:
magnitude
duration
7. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 7
The relatively safer system is one that minimizes the magnitude of the fault voltage
and/or the duration that the fault current exists.
The fault magnitude is determined by:
the impedance of the fault path
the fault voltage.
The impedance of the body, including the contact impedance where the current
enters and where it leaves the body is the limiting factor.
The fault duration is determined by:
how long the body is subjected to the fault current.
EFFECTS OF ELECTRIC FAULT
CURRENT(Contd… )
8. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 8
TYPES OF GROUNDING
System Grounding
Equipment Grounding
9. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 9
System Grounding
NEEDS OF SYSTEM GROUNDING:
1. to limit the voltage imposed by lightning
2. to limit the voltage due to unintentional contact with higher-voltage lines
3. to limit the voltage due to line surges
4. to stabilize the voltage to the earth during normal operation.
10. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 10
Fig 1. System Grounding
11. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 11
The supply system has a connection to ground and is "system" grounded.
When lightning strike to a load side conductor, system grounding provides a path
for the lightning current to travel to the earth.
There is no electrical connection from the faulted supply conductor and the human
in contact with the enclosure.
Line surges, if they are voltage, cannot be reduced by system grounding which is a
current path.
Only surge protective devices can provide a means of short circuiting an
overvoltage to ground.
System Grounding (Contd… )
12. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 12
Sudden opening of single conductor in a 3 phase long distribution system leads to
unstable voltage.
The capacitance to ground and the inductance of the line react to result in ferro-
resonance and an overvoltage can occur.
System grounding changes the capacitance vs inductance relationship and prevents
the overvoltage from occurring.
System grounding provides little assistance in minimizing the amplitude or duration
of downstream faults at equipment.
The fault current must return through the earth with its relatively high resistance
compared to fault supply current conductors.
System Grounding (Contd… )
13. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 13
Equipment Grounding
NEEDS OF EQUIPMENT GROUNDING:
1. to facilitate fault current clearing
2. to minimize the hazardous fault voltage
14. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 14
Fig 2. Equipment Grounding
15. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 15
The supply system has a connection to the earth and is "grounded".
There is a fault at load equipment between the supply ungrounded conductor and
the metal enclosure of the load.
There is a connection to the earth from the equipment enclosure and the equipment
is "grounded". This conductor is truly an "equipment grounding conductor"
Equipment Grounding (Contd…)
16. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 16
The fault voltage at the enclosure with respect to local ground is:
𝑉𝑓𝑎𝑢𝑙𝑡 = 𝐼𝑓𝑎𝑢𝑙𝑡 × 𝑍 𝑟𝑒𝑡𝑢𝑟𝑛
𝐼𝑓𝑎𝑢𝑙𝑡 =
𝑉 𝑠𝑢𝑝𝑝𝑙𝑦
𝑍 𝑝ℎ𝑎𝑠𝑒+𝑍 𝑟𝑒𝑡𝑢𝑟𝑛
𝑉𝑓𝑎𝑢𝑙𝑡 =
𝑉 𝑠𝑢𝑝𝑝𝑙𝑦
𝑍 𝑝ℎ𝑎𝑠𝑒+𝑍 𝑟𝑒𝑡𝑢𝑟𝑛
× 𝑍 𝑟𝑒𝑡𝑢𝑟𝑛
Equipment Grounding (Contd…)
17. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 17
The fault voltage will be very close to the supply voltage by Ohm's Law for series
circuits.
Any increase in conductor size or reduction of circuit length will merely make the
fault voltage higher.
Fault current magnitude is minimal due to the relatively high resistance through the
earth back to the system grounding connection and finally to the source.
Thus equipment grounding, there fore, does not minimize the fault voltage.
Equipment Grounding (Contd…)
18. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 18
Fig 3. Fault Return Conductor
FAULT RETURN CONDUCTOR
19. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 19
The conductor connecting the enclosure directly to the earth has been removed.
A separate conductor has been added between the enclosure and the source.
The added conductor provides a path for the fault current to the source without
passing through the earth.
This conductor is known as “fault return conductor”.
FAULT RETURN CONDUCTOR (Contd…)
20. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 20
The magnitude of the fault voltage can be calculated because the resistance of the
return path is a known quantity.
To provide a high level of fault current, a low-impedance electrically conductive
path from potentially faulted piece of equipment to the system source is necessary.
If that path is through the earth, the impedance of the earth will generally limit the
fault current to low levels that are insufficient for fault clearing.
FAULT RETURN CONDUCTOR (Contd…)
21. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 21
Zero-sequence current sensing:
Use a current transformer to sense the current going and leave the load.
If the currents are not equal, there is a fault current returning to the source by some other
path.
The current transformer output is used to operate the overcurrent device.
Commonly found in kitchens, bathrooms etc.
These devices are capable of opening the circuit in under 1 s.
METHODS OF SENSING AND CLEARING
A FAULT TO EQUIPMENT
22. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 22
By the use of a current transformer surrounding all of the circuit conductors.
If the net current is not zero, the current transformer secondary output is used to trip the
supplying overcurrent device.
Circuit overcurrent protection device:
Circuit breaker, fuse, or relay can provide fault current clearing if the fault current is in
excess of the normal device rating.
Most of these devices have an inverse time-current characteristics.
To operate this device quickly it is necessary to provide a high overcurrent.
METHODS OF SENSING AND CLEARING A FAULT
TO EQUIPMENT (Contd…)
23. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 23
OTHER PATHWAYS
There may be one or more fault return paths in parallel with the fault return wire
conductor.
The other paths are metallic raceways and building steel.
Metallic raceways are considered as a fault return conductor without regard to
material or size.
Raceway encircles the phase conductor, the net magnetic field is near zero inside
raceway, resulting in minimum impedance.
In buildings that have a structural steel metal frame, electrical equipment is often
fastened to the structural steel.
The structural steel is generally bonded to the earth and is a parallel path for the
fault current to return to the source.
24. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 24
Issues that reduce the effectiveness of the raceway as a conductor:
High fault currents flow on the inner surface of the raceway due to eddy currents on
the outer surface.
Reduces the effective cross-sectional area and thus increases the impedance of the
raceway.
High fault currents will saturate the steel and hence increasing the impedance of the
raceway.
OTHER PATHWAYS (Contd…)
25. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 25
The parallel paths make the system safe in following ways:
It reduces the effective fault return impedance.
It reduces the fault voltage.
It reduces the fault current through the human.
It increases the fault current through the overcurrent protective device.
It fasten fault clearing.
OTHER PATHWAYS (Contd…)
26. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 26
CONCLUSIONS
The act of grounding does not make systems safer.
In fact, grounding minimizes the hazardous voltage due to an enclosure fault is a
myth.
The relatively safer system is one that minimizes the magnitude of the fault voltage
and/or the duration of the fault current.
This is accomplished by a combination of an adequately sized fault return
conductor and an overcurrent device with a current versus time characteristic
adequate to operate rapidly.
27. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 27
REFERENCES
1. E. Rappaport, “Grounding vs. bonding—What the National Electrical Code
Does Not Explain”, IEEE Transactions on Industry Applications, Year-2014,
Volume: 50, Issue: 4, Pages: 2776-2779.
2. E.Rappaport, “Does Grounding Make A System Safe? Analyzing the factors
that contribute to electrical safety”, IEEE Industry Applications Magazine •
May|june 2015 Pages:48-57.
3. John P. Nelson ,” Improved Electrical Safety Through High Resistance
Grounding ” IEEE Transactions on Industry Applications, Year: 2015, Volume:
51, Issue: 6 Pages: 5198 – 5203.
4. S. K. Kaul; Jai Kishore , Electrical safety in india - a perspective , Electrical
Safety In Industry, 2000. Proceedings of 2000 IEEE IAS Workshop ,Year: 2000,
Pages: 42 – 47.
28. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 28
5. https://en.wikipedia.org/wiki/Ground_(electricity)
6. http://electrical-engineering-portal.com/good-grounding-system
7. http://electrical-engineering-portal.com/what-is-the-difference-between-bonding-
grounding-and-earthing
8. http://ecmweb.com/power-quality/ground
REFERENCES (Contd…)
29. 5:58 PM DEPARTMENT OF ELECTRICAL AND ELECTRONICS, CE, KIDANGOOR 29
THANK YOU