The document discusses different types of electrical supply systems and earthing methods. It explains that UTAS Shinas receives an 11kV supply from the distribution substation, which is then stepped down to 415V on site. It describes the TN-S, TN-C-S, and TT earthing systems, noting that TN-S uses a cable sheath earth, TN-C-S combines the earth and neutral, and TT provides a direct earth connection without using the neutral. Protective earthing is achieved through bonding exposed metalwork to an effective earth connection for safety.
The document discusses different types of grounding systems used in electrical installations. It describes six common grounding systems: equipment grounds, static grounds, system grounds, maintenance grounds, electronic grounds, and lightning grounds. It provides details on each type, including their objectives and how they are implemented. The document also discusses factors to consider when designing grounding systems and recommendations for proper grounding practices.
There are three main types of earthing systems: TN, TT, and IT. The TN system has the neutral and protective earth conductors combined (TN-C) or separate (TN-S, TN-C-S). The TT system has a local earth connection at each device, while the IT system has no direct connection of the power system to earth. Each system has advantages and disadvantages regarding safety, fault protection, electromagnetic compatibility, and cost. Regulations vary by location regarding the acceptable earthing systems.
The document discusses earthing arrangements and protection against electric shock. It covers the basics of shock protection using Class I and Class II equipment. It then summarizes the three main earthing arrangements: TT, TN-S, and TN-C-S. The TT arrangement uses separate earth electrodes at the supply and installation. The TN-S uses a common earth at the supply but separate earth and neutral conductors at the installation. The TN-C-S, also known as PME, uses a combined earth and neutral conductor on the supply side and separate conductors at the installation.
This application note discusses practical design of earthing electrodes, including the calculation of earthing resistance for various electrode configurations, the materials used for electrodes and their corrosion performance. Equations are given for many common electrode geometries, including horizontal strips, rods, meshes, cable screens and foundations.
Despite the fact that these formulae are derived under the false assumption that soil is boundless and homogenous and ignore the fact that the ground resistivity changes with moisture content, the values obtained, although approximate, are useful in predicting and optimising performance.
This document discusses electrical grounding and earthing systems. It begins by introducing grounding and earthing, and distinguishing between ground and neutral conductors. It then describes different types of earthing systems according to the IEC standard, including TN, TT, and IT networks. The document also covers different types of grounding used in radio communications, AC power installations, and lightning protection. It discusses the concept of virtual ground and multipoint grounding. Overall, the document provides an overview of electrical grounding and earthing systems, their uses, and important concepts.
Earthing, also known as grounding, is based on research that demonstrate that connecting to Earth's electrical energy promotes physical wellbeing. The act of Earthing refers to a physical connection between the electrical frequencies of the human body with that of Earth's (think barefoot in the grass, or at the beach).
The document discusses earthing arrangements and protection against electric shock. It defines key terms like earthing, protective conductors, and fault conditions. It describes the three common earthing arrangements - TT, TN-S, and TN-C-S systems. For each system, it explains the wiring configuration and how fault currents flow. Protection methods like RCDs and their operation are also covered to prevent electric shock. Diagrams and formulas are provided to calculate touch voltages and ensure safety.
The document discusses different types of electrical supply systems and earthing methods. It explains that UTAS Shinas receives an 11kV supply from the distribution substation, which is then stepped down to 415V on site. It describes the TN-S, TN-C-S, and TT earthing systems, noting that TN-S uses a cable sheath earth, TN-C-S combines the earth and neutral, and TT provides a direct earth connection without using the neutral. Protective earthing is achieved through bonding exposed metalwork to an effective earth connection for safety.
The document discusses different types of grounding systems used in electrical installations. It describes six common grounding systems: equipment grounds, static grounds, system grounds, maintenance grounds, electronic grounds, and lightning grounds. It provides details on each type, including their objectives and how they are implemented. The document also discusses factors to consider when designing grounding systems and recommendations for proper grounding practices.
There are three main types of earthing systems: TN, TT, and IT. The TN system has the neutral and protective earth conductors combined (TN-C) or separate (TN-S, TN-C-S). The TT system has a local earth connection at each device, while the IT system has no direct connection of the power system to earth. Each system has advantages and disadvantages regarding safety, fault protection, electromagnetic compatibility, and cost. Regulations vary by location regarding the acceptable earthing systems.
The document discusses earthing arrangements and protection against electric shock. It covers the basics of shock protection using Class I and Class II equipment. It then summarizes the three main earthing arrangements: TT, TN-S, and TN-C-S. The TT arrangement uses separate earth electrodes at the supply and installation. The TN-S uses a common earth at the supply but separate earth and neutral conductors at the installation. The TN-C-S, also known as PME, uses a combined earth and neutral conductor on the supply side and separate conductors at the installation.
This application note discusses practical design of earthing electrodes, including the calculation of earthing resistance for various electrode configurations, the materials used for electrodes and their corrosion performance. Equations are given for many common electrode geometries, including horizontal strips, rods, meshes, cable screens and foundations.
Despite the fact that these formulae are derived under the false assumption that soil is boundless and homogenous and ignore the fact that the ground resistivity changes with moisture content, the values obtained, although approximate, are useful in predicting and optimising performance.
This document discusses electrical grounding and earthing systems. It begins by introducing grounding and earthing, and distinguishing between ground and neutral conductors. It then describes different types of earthing systems according to the IEC standard, including TN, TT, and IT networks. The document also covers different types of grounding used in radio communications, AC power installations, and lightning protection. It discusses the concept of virtual ground and multipoint grounding. Overall, the document provides an overview of electrical grounding and earthing systems, their uses, and important concepts.
Earthing, also known as grounding, is based on research that demonstrate that connecting to Earth's electrical energy promotes physical wellbeing. The act of Earthing refers to a physical connection between the electrical frequencies of the human body with that of Earth's (think barefoot in the grass, or at the beach).
The document discusses earthing arrangements and protection against electric shock. It defines key terms like earthing, protective conductors, and fault conditions. It describes the three common earthing arrangements - TT, TN-S, and TN-C-S systems. For each system, it explains the wiring configuration and how fault currents flow. Protection methods like RCDs and their operation are also covered to prevent electric shock. Diagrams and formulas are provided to calculate touch voltages and ensure safety.
Earthing arrangement(s) at mines & quarries in NSW showing the 'tension' with AS/NZS 3000:2007 definitions. AS/NZS 3000 is a mandatory standard on the surface of mines in NSW
TRANSMISSION AND DISTRIBUTION OF ELECTRIC POWER PROJECT.pptxPrabhakarTripathi16
TDEP aims to supply electrical energy by transmitting electricity at high voltages from power plants to substations, where it is converted to lower voltages for distribution. Key components of the transmission and distribution system include turbines, generators, transformers, conductors, insulators, circuit breakers, relays, and current/potential transformers. Proper site selection factors for substations include type, land requirements, communication/amenity access, and drainage.
1. The document discusses earth/ground resistance measurement and why it is important for electrical safety. Regular measurements of the earth resistance can prove that an electrical installation is operating correctly.
2. An effective earth electrode alone is not enough to guarantee safety - it must be connected to a protective system like a residual current device (RCD). The acceptable maximum value of earth resistance depends on factors like the rated current of the RCD.
3. Soil resistivity measurements help determine the optimal locations and types of earth electrodes by measuring how well different types of soil conduct electricity. The Wenner and Schlumberger methods are commonly used to measure soil resistivity.
This document provides information on various topics related to electricity and electrical systems in buildings. It discusses different sources of electricity generation in India as well as defines key electrical terms like current, voltage, and electrical energy. It also describes components of electrical systems like transformers, overhead power lines, fuses, circuit breakers, meters, and earthing systems. Furthermore, it covers different types of electrical wiring and distribution systems used in residential buildings.
Earthing and grounding systems are used to protect humans and equipment from electric shocks. Earthing works by providing an alternative path for fault currents to flow safely into the earth, rather than through a person. It connects exposed metal parts to the earth to drain away stray currents. Grounding provides an effective return path for main currents and protects power system equipment. While both terms refer to connecting to earth, earthing focuses on safety and protection, while grounding balances unbalanced loads and provides a return path. A complete earthing system includes an earth continuity conductor, earthing lead, and earth electrode buried underground. Proper earthing is important for safety and reliability of electrical installations.
Consideration of Three Phase Faults on Transmission Line with Distance Protec...ijtsrd
In a modern power system, electrical energy from the generating station is delivered to the consumers through a network of transmission and distribution. Transmission lines are also important elements of electric power system and require attention of protecting for safety against the possible faults occurring on them. The detection of a fault and disconnection of a faulty section or apparatus can be achieved by using fuses or relays in conjunction with circuit breakers. Distance relay has the ability to detect a fault within a distance along a transmission line or cable from its location. Distance relay protection is the most widely used in case of high voltage and extra high voltage in the transmission line. In this paper discussion about how to protect the long transmission line with distance relay. June Tharaphe Lwin | Christ Tine Lin "Consideration of Three Phase Faults on Transmission Line with Distance Protection" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd28013.pdfPaper URL: https://www.ijtsrd.com/engineering/electrical-engineering/28013/consideration-of-three-phase-faults-on-transmission-line-with-distance-protection/june-tharaphe-lwin
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.
This document discusses different types of electrical wiring devices and consumable items. It identifies conductors, switches, receptacles, contactors, and relays as common wiring devices. Conductors can be bare, covered, or insulated. Switches include single pole switches, three-way switches, four-way switches, timer switches, sensor switches, and dimmer switches. Receptacles include duplex receptacles, straight blade receptacles, and floor box receptacles. The document provides brief descriptions of each type of wiring device and advises on how to properly select wiring devices according to manufacturer, warranty, support, and job requirements.
Earthing systems, also known as grounding systems, are crucial for electrical safety, and they come in various types. The choice of the earthing system depends on the specific requirements of the electrical installation and local regulations. Here are some common types of earthing systems:
TT System (Terre-à-Terre):
In a TT system, each electrical device or installation is individually grounded to the earth.
It is commonly used for residential buildings, where each outlet is connected to a local grounding electrode.
Provides a good level of safety but may require more ground electrodes.
TN System (Terre-Neutre):
In a TN system, the electrical devices are connected to a common grounding point, which is also connected to the neutral of the power supply.
There are three main variations of the TN system:
a. TN-S: Separate protective and neutral conductors.
b. TN-C: Combined protective and neutral conductors for part of the installation, with separate conductors for other parts.
c. TN-C-S: A combination of TN-C and TN-S within the same installation.
TN systems are commonly used in residential and commercial applications.
IT System (Isolated Terre):
In an IT system, the grounding is intentionally isolated from the power supply neutral.
This system is often used in critical applications where electrical continuity is vital, such as hospitals and data centers.
It provides a high level of reliability, especially in the event of a single fault.
Solid Grounding System:
A solid grounding system is characterized by a direct connection between the electrical system and a grounding electrode.
It is used in various applications to ensure that faults are quickly cleared and the electrical system is safe.
Impedance Grounding System:
An impedance grounding system involves adding resistance or reactance between the grounding electrode and the electrical system.
This type of grounding can be used to limit fault currents and reduce the risk of electrical shock and equipment damage.
Plate or Rod Electrodes:
These are physical grounding electrodes, such as copper rods or plates, that are buried in the earth to establish a connection to the ground.
Plate or rod electrodes are commonly used in conjunction with various grounding systems.
Counterpoise Grounding System:
This type of grounding is often used in radio and telecommunications systems.
A counterpoise is a network of wires, typically above ground, that serves as a ground reference for antennas and signal transmission.
Chemical Grounding:
In some cases, chemicals, such as conductive compounds or salts, are used to improve the conductivity of the grounding electrode, especially in areas with high soil resistivity.
The choice of the appropriate earthing system depends on factors like the local electrical codes, the type of electrical installation, safety requirements, and the environment. Proper earthing is crucial for electrical safety and the reliable operation of electrical systems.
Types of Earthing Systems: Ensuring Electrical Safety
Introduction
Electrical safety is paramount in all aspects of life, from homes to industrial facilities. Electrical systems can pose serious risks, but these can be mitigated through earthing systems. Earthing, or grounding, involves connecting electrical systems and equipment to the Earth's surface. This provides a path for fault currents to dissipate and prevents electrical hazards. Different types of earthing systems have been developed to meet various safety and operational needs. In this guide, we explore these systems, their applications, selection criteria, and their advantages and disadvantages.
The Importance of Earthing Systems
To understand the significance of earthing systems, it's crucial to recognize the dangers posed by electrical faults. Electrical systems rely on the flow of electrons to carry electrical energy. However, faults such as short circuits or equipment malfunctions can lead to excessive current flow, causing hazards like electric shock, equipment damage, and fires.
Earthing addresses these dangers by providing a low-resistance path for fault currents to safely reach the Earth's surface. This serves several vital purposes:
Safety: Earthing reduces the risk of electric shock by ensuring that fault currents avoid human contact and flow harmlessly to the Earth.
Equipment Protection: It safeguards electrical equipment by directing fault currents away from sensitive components, preventing damage.
Voltage Stabilization: Earthing helps maintain stable voltage levels, ensuring that electrical equipment operates within specified limits.
Fire Prevention: By safely dissipating fault currents, earthing systems minimize the risk of electrical fires, protecting lives and property.
Continuity of Supply: These systems contribute to the uninterrupted supply of electrical energy by reducing downtime caused by faults.
Common Types of Earthing Systems
Several earthing systems exist, each with distinct characteristics and applications. The choice of an earthing system depends on factors like the type of installation, local regulations, and environmental conditions. Here, we explore the most common types:
TT System (Terre-Terre): In the TT system, each electrical installation has its dedicated grounding connection to the Earth. This setup is typical in residential and small-scale installations.
TN System (Terre-Neutre): The TN system combines grounding for both the earth and neutral conductors. It includes subtypes like TN-C, TN-S, and TN-C-S, commonly found in industrial and commercial installations.
IT System (Isolated Terre): In the IT system, there's no direct connection to Earth, and insulation is maintained at a high level. It is preferred in sensitive environments like hospitals and data centres.
The document discusses electrical safety regulations for photovoltaic power plants connected to low voltage networks in Spain. Key points include:
1) Royal Decree 1663/2000 establishes safety requirements for PV plants up to 100 KVA connected to networks under 1 KV.
2) Protections required by this decree include a general manual switch, circuit breaker, earth leakage circuit breaker, interconnect switch, and inverter protections for voltage/frequency.
3) PV panels use an IT earthing system where modules are isolated but mounting structures are earthed, preventing electric currents through a person if they touch exposed metal.
This document discusses earthing systems used in telecom installations. It defines earthing and its objectives, which include reducing crosstalk and noise, providing reliability, and protecting equipment and personnel. The document outlines the requirements for effective earthing systems, including low resistance and corrosion resistance. It describes different types of earthing systems, including service earthing and protective earthing. Common versus separate earthing systems are compared, with common earthing noted as preferable. Design principles for earthing systems are provided.
DC and AC bridges are used to measure resistance, inductance, capacitance, and impedance with high accuracy. Two main types of bridges exist: DC bridges like the Wheatstone and Kelvin bridges, and AC bridges like the Similar Angle, Opposite Angle, Maxwell, Wein, and Radio Frequency bridges. Bridges operate on the null indication principle where the measurement is independent of calibration errors. Thévenin's theorem is an analytical tool used to analyze unbalanced bridges, representing electrical networks as a voltage source and resistor. Standards help ensure compatibility between electrical systems and establish limits to reduce interference. Common EMI control techniques include grounding to reduce potential differences, shielding to contain fields, and filtering to block unwanted frequencies
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.
This document provides an overview of electrical and electronic systems, quantities, units, and safety. It discusses:
1) Systems are groups of interrelated parts that perform a specific function via inputs and outputs. Electrical systems deal with electric power, electronic systems deal with signals.
2) Important units include the volt, ampere, ohm, watt, and engineering prefixes like milli, mega and giga. Metric conversions and rounding rules are also covered.
3) Circuit components like resistors, switches, and meters are described. Resistor color codes, variable resistors, and schematic symbols are discussed. Basic electric circuits, current, resistance and safety guidelines are summarized.
1) The document discusses key concepts in electrical systems including systems, inputs/outputs, circuits, voltage, current, resistance, and measurement devices.
2) It defines important units like volts, amps, and ohms and describes metric prefixes for large and small units.
3) Safety tips are provided for working with electrical circuits including maintaining a clean workspace and knowing emergency procedures.
The document describes a shock proof wiring system that uses an isolation transformer to convert a standard wiring system into a shockproof system. It discusses how isolation transformers work to isolate the wiring circuit from the ground, preventing electric shocks even if a person touches a live wire. The system aims to provide protection from electrical shocks by disconnecting the circuit path between the electricity source earth and the person touching a wire. It works by installing a single-phase isolation transformer that has an ungrounded secondary winding, so the output is isolated from the earth. This isolation prevents current from flowing from the source through a person to the earth if they touch a live wire, eliminating the risk of electric shock.
This document describes the development of a shock proof wiring system. The system uses an isolation transformer to disconnect the earthing circuit between the power station and a home, eliminating the path for electric current to flow through the body in the event of contact with a live wire. By isolating the earthing at the secondary side of the transformer, the system converts a general wiring system into a shockproof one where contact with a single live wire would not result in electric shock. The document discusses electric shocks, earthing concepts, and provides diagrams of the typical electric path in a home wiring system versus the isolated path using the proposed shockproof system.
PPT on earthing, grounding and isolation made by the students of SVIT,Vasad under the valuable guidance of the faculties teaching us Electronics and Electrical workshop(EEW) under the course of GTU.
Earthing arrangement(s) at mines & quarries in NSW showing the 'tension' with AS/NZS 3000:2007 definitions. AS/NZS 3000 is a mandatory standard on the surface of mines in NSW
TRANSMISSION AND DISTRIBUTION OF ELECTRIC POWER PROJECT.pptxPrabhakarTripathi16
TDEP aims to supply electrical energy by transmitting electricity at high voltages from power plants to substations, where it is converted to lower voltages for distribution. Key components of the transmission and distribution system include turbines, generators, transformers, conductors, insulators, circuit breakers, relays, and current/potential transformers. Proper site selection factors for substations include type, land requirements, communication/amenity access, and drainage.
1. The document discusses earth/ground resistance measurement and why it is important for electrical safety. Regular measurements of the earth resistance can prove that an electrical installation is operating correctly.
2. An effective earth electrode alone is not enough to guarantee safety - it must be connected to a protective system like a residual current device (RCD). The acceptable maximum value of earth resistance depends on factors like the rated current of the RCD.
3. Soil resistivity measurements help determine the optimal locations and types of earth electrodes by measuring how well different types of soil conduct electricity. The Wenner and Schlumberger methods are commonly used to measure soil resistivity.
This document provides information on various topics related to electricity and electrical systems in buildings. It discusses different sources of electricity generation in India as well as defines key electrical terms like current, voltage, and electrical energy. It also describes components of electrical systems like transformers, overhead power lines, fuses, circuit breakers, meters, and earthing systems. Furthermore, it covers different types of electrical wiring and distribution systems used in residential buildings.
Earthing and grounding systems are used to protect humans and equipment from electric shocks. Earthing works by providing an alternative path for fault currents to flow safely into the earth, rather than through a person. It connects exposed metal parts to the earth to drain away stray currents. Grounding provides an effective return path for main currents and protects power system equipment. While both terms refer to connecting to earth, earthing focuses on safety and protection, while grounding balances unbalanced loads and provides a return path. A complete earthing system includes an earth continuity conductor, earthing lead, and earth electrode buried underground. Proper earthing is important for safety and reliability of electrical installations.
Consideration of Three Phase Faults on Transmission Line with Distance Protec...ijtsrd
In a modern power system, electrical energy from the generating station is delivered to the consumers through a network of transmission and distribution. Transmission lines are also important elements of electric power system and require attention of protecting for safety against the possible faults occurring on them. The detection of a fault and disconnection of a faulty section or apparatus can be achieved by using fuses or relays in conjunction with circuit breakers. Distance relay has the ability to detect a fault within a distance along a transmission line or cable from its location. Distance relay protection is the most widely used in case of high voltage and extra high voltage in the transmission line. In this paper discussion about how to protect the long transmission line with distance relay. June Tharaphe Lwin | Christ Tine Lin "Consideration of Three Phase Faults on Transmission Line with Distance Protection" Published in International Journal of Trend in Scientific Research and Development (ijtsrd), ISSN: 2456-6470, Volume-3 | Issue-5 , August 2019, URL: https://www.ijtsrd.com/papers/ijtsrd28013.pdfPaper URL: https://www.ijtsrd.com/engineering/electrical-engineering/28013/consideration-of-three-phase-faults-on-transmission-line-with-distance-protection/june-tharaphe-lwin
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.
This document discusses different types of electrical wiring devices and consumable items. It identifies conductors, switches, receptacles, contactors, and relays as common wiring devices. Conductors can be bare, covered, or insulated. Switches include single pole switches, three-way switches, four-way switches, timer switches, sensor switches, and dimmer switches. Receptacles include duplex receptacles, straight blade receptacles, and floor box receptacles. The document provides brief descriptions of each type of wiring device and advises on how to properly select wiring devices according to manufacturer, warranty, support, and job requirements.
Earthing systems, also known as grounding systems, are crucial for electrical safety, and they come in various types. The choice of the earthing system depends on the specific requirements of the electrical installation and local regulations. Here are some common types of earthing systems:
TT System (Terre-à-Terre):
In a TT system, each electrical device or installation is individually grounded to the earth.
It is commonly used for residential buildings, where each outlet is connected to a local grounding electrode.
Provides a good level of safety but may require more ground electrodes.
TN System (Terre-Neutre):
In a TN system, the electrical devices are connected to a common grounding point, which is also connected to the neutral of the power supply.
There are three main variations of the TN system:
a. TN-S: Separate protective and neutral conductors.
b. TN-C: Combined protective and neutral conductors for part of the installation, with separate conductors for other parts.
c. TN-C-S: A combination of TN-C and TN-S within the same installation.
TN systems are commonly used in residential and commercial applications.
IT System (Isolated Terre):
In an IT system, the grounding is intentionally isolated from the power supply neutral.
This system is often used in critical applications where electrical continuity is vital, such as hospitals and data centers.
It provides a high level of reliability, especially in the event of a single fault.
Solid Grounding System:
A solid grounding system is characterized by a direct connection between the electrical system and a grounding electrode.
It is used in various applications to ensure that faults are quickly cleared and the electrical system is safe.
Impedance Grounding System:
An impedance grounding system involves adding resistance or reactance between the grounding electrode and the electrical system.
This type of grounding can be used to limit fault currents and reduce the risk of electrical shock and equipment damage.
Plate or Rod Electrodes:
These are physical grounding electrodes, such as copper rods or plates, that are buried in the earth to establish a connection to the ground.
Plate or rod electrodes are commonly used in conjunction with various grounding systems.
Counterpoise Grounding System:
This type of grounding is often used in radio and telecommunications systems.
A counterpoise is a network of wires, typically above ground, that serves as a ground reference for antennas and signal transmission.
Chemical Grounding:
In some cases, chemicals, such as conductive compounds or salts, are used to improve the conductivity of the grounding electrode, especially in areas with high soil resistivity.
The choice of the appropriate earthing system depends on factors like the local electrical codes, the type of electrical installation, safety requirements, and the environment. Proper earthing is crucial for electrical safety and the reliable operation of electrical systems.
Types of Earthing Systems: Ensuring Electrical Safety
Introduction
Electrical safety is paramount in all aspects of life, from homes to industrial facilities. Electrical systems can pose serious risks, but these can be mitigated through earthing systems. Earthing, or grounding, involves connecting electrical systems and equipment to the Earth's surface. This provides a path for fault currents to dissipate and prevents electrical hazards. Different types of earthing systems have been developed to meet various safety and operational needs. In this guide, we explore these systems, their applications, selection criteria, and their advantages and disadvantages.
The Importance of Earthing Systems
To understand the significance of earthing systems, it's crucial to recognize the dangers posed by electrical faults. Electrical systems rely on the flow of electrons to carry electrical energy. However, faults such as short circuits or equipment malfunctions can lead to excessive current flow, causing hazards like electric shock, equipment damage, and fires.
Earthing addresses these dangers by providing a low-resistance path for fault currents to safely reach the Earth's surface. This serves several vital purposes:
Safety: Earthing reduces the risk of electric shock by ensuring that fault currents avoid human contact and flow harmlessly to the Earth.
Equipment Protection: It safeguards electrical equipment by directing fault currents away from sensitive components, preventing damage.
Voltage Stabilization: Earthing helps maintain stable voltage levels, ensuring that electrical equipment operates within specified limits.
Fire Prevention: By safely dissipating fault currents, earthing systems minimize the risk of electrical fires, protecting lives and property.
Continuity of Supply: These systems contribute to the uninterrupted supply of electrical energy by reducing downtime caused by faults.
Common Types of Earthing Systems
Several earthing systems exist, each with distinct characteristics and applications. The choice of an earthing system depends on factors like the type of installation, local regulations, and environmental conditions. Here, we explore the most common types:
TT System (Terre-Terre): In the TT system, each electrical installation has its dedicated grounding connection to the Earth. This setup is typical in residential and small-scale installations.
TN System (Terre-Neutre): The TN system combines grounding for both the earth and neutral conductors. It includes subtypes like TN-C, TN-S, and TN-C-S, commonly found in industrial and commercial installations.
IT System (Isolated Terre): In the IT system, there's no direct connection to Earth, and insulation is maintained at a high level. It is preferred in sensitive environments like hospitals and data centres.
The document discusses electrical safety regulations for photovoltaic power plants connected to low voltage networks in Spain. Key points include:
1) Royal Decree 1663/2000 establishes safety requirements for PV plants up to 100 KVA connected to networks under 1 KV.
2) Protections required by this decree include a general manual switch, circuit breaker, earth leakage circuit breaker, interconnect switch, and inverter protections for voltage/frequency.
3) PV panels use an IT earthing system where modules are isolated but mounting structures are earthed, preventing electric currents through a person if they touch exposed metal.
This document discusses earthing systems used in telecom installations. It defines earthing and its objectives, which include reducing crosstalk and noise, providing reliability, and protecting equipment and personnel. The document outlines the requirements for effective earthing systems, including low resistance and corrosion resistance. It describes different types of earthing systems, including service earthing and protective earthing. Common versus separate earthing systems are compared, with common earthing noted as preferable. Design principles for earthing systems are provided.
DC and AC bridges are used to measure resistance, inductance, capacitance, and impedance with high accuracy. Two main types of bridges exist: DC bridges like the Wheatstone and Kelvin bridges, and AC bridges like the Similar Angle, Opposite Angle, Maxwell, Wein, and Radio Frequency bridges. Bridges operate on the null indication principle where the measurement is independent of calibration errors. Thévenin's theorem is an analytical tool used to analyze unbalanced bridges, representing electrical networks as a voltage source and resistor. Standards help ensure compatibility between electrical systems and establish limits to reduce interference. Common EMI control techniques include grounding to reduce potential differences, shielding to contain fields, and filtering to block unwanted frequencies
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.
This document provides an overview of electrical and electronic systems, quantities, units, and safety. It discusses:
1) Systems are groups of interrelated parts that perform a specific function via inputs and outputs. Electrical systems deal with electric power, electronic systems deal with signals.
2) Important units include the volt, ampere, ohm, watt, and engineering prefixes like milli, mega and giga. Metric conversions and rounding rules are also covered.
3) Circuit components like resistors, switches, and meters are described. Resistor color codes, variable resistors, and schematic symbols are discussed. Basic electric circuits, current, resistance and safety guidelines are summarized.
1) The document discusses key concepts in electrical systems including systems, inputs/outputs, circuits, voltage, current, resistance, and measurement devices.
2) It defines important units like volts, amps, and ohms and describes metric prefixes for large and small units.
3) Safety tips are provided for working with electrical circuits including maintaining a clean workspace and knowing emergency procedures.
The document describes a shock proof wiring system that uses an isolation transformer to convert a standard wiring system into a shockproof system. It discusses how isolation transformers work to isolate the wiring circuit from the ground, preventing electric shocks even if a person touches a live wire. The system aims to provide protection from electrical shocks by disconnecting the circuit path between the electricity source earth and the person touching a wire. It works by installing a single-phase isolation transformer that has an ungrounded secondary winding, so the output is isolated from the earth. This isolation prevents current from flowing from the source through a person to the earth if they touch a live wire, eliminating the risk of electric shock.
This document describes the development of a shock proof wiring system. The system uses an isolation transformer to disconnect the earthing circuit between the power station and a home, eliminating the path for electric current to flow through the body in the event of contact with a live wire. By isolating the earthing at the secondary side of the transformer, the system converts a general wiring system into a shockproof one where contact with a single live wire would not result in electric shock. The document discusses electric shocks, earthing concepts, and provides diagrams of the typical electric path in a home wiring system versus the isolated path using the proposed shockproof system.
PPT on earthing, grounding and isolation made by the students of SVIT,Vasad under the valuable guidance of the faculties teaching us Electronics and Electrical workshop(EEW) under the course of GTU.
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1. Types of Earthing Systems —
What does TT, IT & TN Earthing
mean?
Standards Used for Earthing Systems Definitions
Over the past century, Electrical Safety Standards have evolved into highly
developed systems that cover all the major aspects for a safe installation,
including Earthing Systems. In Low-voltage (LV) Electrical Installations, the
reference standard IEC 60364 is used for the measures to be implemented to
guarantee the protection of personnel and property.
The IEC 60364 standard has defined three types of Earthing Systems, namely
TT, IT, and TN systems. Since IEC publishes International Standards for all
electrical, electronic, and related technologies and is the leading international
organization in its field, IEC 60364 is the apex level document that informs the
standards for LV Electrical Installations around the world. Therefore, the three
types of earthing systems defined in IEC 60364 are also recognized in many
national standards. BS 7671: 2008, also known as the IEE Wiring Regulations
17th Edition is the British Standard published on January 2008 used by the UK
2. and other countries. Similarly, Indian Standard IS 732:1989 (R2015) is used in
India for electrical installations.
Types of Earthing Systems
As mentioned above, the three major types of Earthing Systems used by IEC
60364 are
1. TT
2. IT
3. TN — TN-C, TN-S, TN-C-S
The TN system is further subdivided into TN-C, TN-S and TN-C-S and thus we
will refer to 5 types of Earthing Systems prevalent worldwide.
Nomenclature
The First Letter of each system refers to the power source from a star-connected
winding.
The Second Letter refers to the consuming equipment that needs to be earthed.
From the ‘Handbook of Electrical Engineering: For Practitioners In The Oil, Gas
And Petrochemical Industry’ by Alan L. Sheldrake
3. For the first letter, “T denotes that the start point of the source is solidly
connected to earth, which is usually at a location very near to the winding.
I denote that the start point and the winding are isolated from earth. The start
point is usually connected to an inductive impedance or resistance. Capacitive
impedance is never used.”
And for the second letter, “T denotes that the consumer has solidly earthed
independently of the source earthing method.
N denotes that a low impedance conductor is taken from the earth connection at
the source and routed directly to the consumer for the specific purpose of
earthing the consuming equipment.
S denotes that the neutral conductor routed from the source is separate from the
protective earthing conductor, which is also routed from the source. This implies
that five conductors need to be routed for a three-phase consumer.
C denotes that the neutral conductor and the protective earthing conductor are
one and the same conductor. This means that four conductors need to be routed
for a three-phase consumer.”
4. To put it in simpler terms:
T = Direct connection to the Earth, T stands for Terra meaning earth
I = Isolated
N = Neutral
S = Separate
C = Combine
The most common systems are TT and TN. A few countries, such as Norway, use
the IT system. The table below table lists examples of the Earthing Systems used
for public distribution (LV Consumers) in a few countries.
TT Earthing System
In this type of Earthing System, connection to the supply source is directly
connected to earth & load end or installation metalwork is also directly
connected to the earth. Therefore, in case of an overhead line, the mass of the
earth will be the return path for the line. The neutral and earthing conductor
must be separated through the installation because the power distributor only
provides the supply neutral or protective conductor for the connection to the
consumer.
5. IT Earthing System
The distributor system does not have any connections to earth or it has only a
high impedance connection. The basic feature of IT earthing system is that in
the event of a fault between phases and earth, the system can continue to operate
without interruption. Such a fault is referred to as a “first fault”. Thus, usual
earthing protection is not effective for this system and this type is not meant for
consumer power supply. The IT Earthing System is used for power distribution
systems such as substations or generators.
TN-S Earthing System
In this system, the Ground Conductor & Neutral Conductor are separate
throughout the distribution system. The protective conductor is the metallic
covering of the cable supplying the installation. All the exposed conductive parts
of the installation are connected to this protective conductor or via the main
earthing terminal of the installation.
TN-C Earthing System
The Neutral and the protective earth are combined into a single conductor
throughout the system. All the exposed & conductive parts of the installation are
connected to the PEN conductor. As per the 8(4) of the Electricity Safety, Quality
and Continuity Regulations 2002, “Consumer shall not combine the neutral and
protective functions in a single conductor in his customer’s installation”.
6. TN-C-S Earthing System
The Neutral and the protective earth are combined in a single conductor in a
part of the system. This type of earthing is also known as multiple protective
earthing. The supply system PEN conductor is earthed at two or more points and
an earth electrode may be necessary at or near the consumer’s installation. All
the exposed conductive parts of the installation are connected to the PEN
conductor via the main earthing terminal & the neutral terminal and these
terminals are linked together.
