This document discusses five learning outcomes related to electrical heating: 1) heat and temperature, heat capacity and heat transfer, 2) methods for controlling heating in different situations, 3) processes and techniques for water, space, and industrial heating, 4) AS3000:2007 wiring rules requirements, and 5) potential causes of malfunction in electric heating equipment and tests for diagnosing faults.
This document discusses different types of insulating materials used in building construction and engineering. It defines insulating materials as those that retard or stop the flow of heat, electricity, or sound. There are three main types of insulators: thermal insulators, electrical insulators, and sound insulators. Some common thermal insulators mentioned include magnesium plastic, aluminum foils, asbestos, cork, cellular rubber, and mineral wool. Common electrical insulators include mica, asbestos, rubber, paper, synthetic resins like Bakelite, porcelain, glass, and cotton. Sound insulators discussed are cellular concrete and acoustic plaster and boards.
This document discusses earthing, which is used to protect electrical systems and users from shock by providing a path for fault currents to flow safely to the earth. It defines key terms like earthing, earth electrode, and describes conventional earthing methods like plate and rod earthing which involve burying conductive plates or rods underground to dissipate electric currents. The objectives of earthing are to ensure exposed parts do not reach a dangerous potential and protect machinery from short circuits. Proper earthing is important for buildings, industries, and other applications using electricity.
The document discusses different types of electrical insulators used in power transmission and distribution systems. It describes pin insulators, which are used for voltages up to 33kV and secure the conductor to cross-arms on poles. For higher voltages, suspension insulators are used, consisting of multiple porcelain discs connected in series. Strain insulators are used where there are sharp turns or high tension, using assemblies of suspension insulators or shackle insulators for lower voltages. Each type of insulator is designed to support and isolate electrical conductors without allowing current flow.
In early days, there was a little demand for electrical energy so that small power stations were built to supply lighting and heating loads. However, the widespread use of electrical energy by modern civilisation has necessitated to produce bulk electrical energy economically and efficiently.
The increased demand of electrical energy can be met by building big power stations at favourable places where fuel (coal or gas) or water energy is available in abundance.
This document summarizes different types of power cables. It describes the general construction of cables which includes a conductor, insulation, sheath, bedding, armouring and serving. It then discusses various cable types such as belted cables, screened cables, super tension cables, oil filled cables and gas pressure cables. Screened cables include H-type and S.L. cables. The document provides details on the construction and advantages and disadvantages of each cable type.
Chapter 4 mechanical design of transmission linesfiraoltemesgen1
This chapter discusses the mechanical design of transmission lines. It covers various topics such as types of conductors, line supports, spacing between conductors, and sag-tension calculations. The key conductors mentioned are copper, aluminum, and steel. Wooden poles, steel tubular poles, reinforced concrete poles, and steel towers are described as the main types of line supports. The document also discusses the effects of wind and ice loading on transmission lines. Sag-tension calculations are explained using catenary curve equations.
The document discusses electrical power distribution systems. It defines primary and secondary distribution systems based on voltage level. Primary distribution exists between distribution substations and transformers, while secondary distribution receives power from transformer secondaries and supplies various loads. The document also describes radial and ring main distribution network configurations and their relative advantages. Requirements for good distribution systems like continuity of supply and limited voltage variation are also outlined.
This document discusses five learning outcomes related to electrical heating: 1) heat and temperature, heat capacity and heat transfer, 2) methods for controlling heating in different situations, 3) processes and techniques for water, space, and industrial heating, 4) AS3000:2007 wiring rules requirements, and 5) potential causes of malfunction in electric heating equipment and tests for diagnosing faults.
This document discusses different types of insulating materials used in building construction and engineering. It defines insulating materials as those that retard or stop the flow of heat, electricity, or sound. There are three main types of insulators: thermal insulators, electrical insulators, and sound insulators. Some common thermal insulators mentioned include magnesium plastic, aluminum foils, asbestos, cork, cellular rubber, and mineral wool. Common electrical insulators include mica, asbestos, rubber, paper, synthetic resins like Bakelite, porcelain, glass, and cotton. Sound insulators discussed are cellular concrete and acoustic plaster and boards.
This document discusses earthing, which is used to protect electrical systems and users from shock by providing a path for fault currents to flow safely to the earth. It defines key terms like earthing, earth electrode, and describes conventional earthing methods like plate and rod earthing which involve burying conductive plates or rods underground to dissipate electric currents. The objectives of earthing are to ensure exposed parts do not reach a dangerous potential and protect machinery from short circuits. Proper earthing is important for buildings, industries, and other applications using electricity.
The document discusses different types of electrical insulators used in power transmission and distribution systems. It describes pin insulators, which are used for voltages up to 33kV and secure the conductor to cross-arms on poles. For higher voltages, suspension insulators are used, consisting of multiple porcelain discs connected in series. Strain insulators are used where there are sharp turns or high tension, using assemblies of suspension insulators or shackle insulators for lower voltages. Each type of insulator is designed to support and isolate electrical conductors without allowing current flow.
In early days, there was a little demand for electrical energy so that small power stations were built to supply lighting and heating loads. However, the widespread use of electrical energy by modern civilisation has necessitated to produce bulk electrical energy economically and efficiently.
The increased demand of electrical energy can be met by building big power stations at favourable places where fuel (coal or gas) or water energy is available in abundance.
This document summarizes different types of power cables. It describes the general construction of cables which includes a conductor, insulation, sheath, bedding, armouring and serving. It then discusses various cable types such as belted cables, screened cables, super tension cables, oil filled cables and gas pressure cables. Screened cables include H-type and S.L. cables. The document provides details on the construction and advantages and disadvantages of each cable type.
Chapter 4 mechanical design of transmission linesfiraoltemesgen1
This chapter discusses the mechanical design of transmission lines. It covers various topics such as types of conductors, line supports, spacing between conductors, and sag-tension calculations. The key conductors mentioned are copper, aluminum, and steel. Wooden poles, steel tubular poles, reinforced concrete poles, and steel towers are described as the main types of line supports. The document also discusses the effects of wind and ice loading on transmission lines. Sag-tension calculations are explained using catenary curve equations.
The document discusses electrical power distribution systems. It defines primary and secondary distribution systems based on voltage level. Primary distribution exists between distribution substations and transformers, while secondary distribution receives power from transformer secondaries and supplies various loads. The document also describes radial and ring main distribution network configurations and their relative advantages. Requirements for good distribution systems like continuity of supply and limited voltage variation are also outlined.
This is a small ppt made by me to describe about the basics of Insulators in HV , EHV transmission lines.Students who want to go through the basics for clearing the fundamentals they can go through this ppt. Thank you.
The document discusses types of underground power cables. It describes single-core and multi-core cables, their construction including conductor, insulation, sheathing, and armor. It discusses cable classification based on operating voltage and insulation material. Methods of cable laying and factors affecting reliability are also summarized. Cable testing methods include insulation resistance testing and capacitance testing to determine cable parameters.
Electrical wiring system - and estimation Mahfuz Sikder
The document discusses different types of electrical wiring systems used for domestic and commercial buildings. It covers various wiring methods like cleat wiring, wooden casing and capping wiring, lead sheathed wiring, conduit piping wiring and CTS/TRS sheathed wiring. For each method, it discusses the materials used, advantages, disadvantages and applications. The document also provides guidelines for domestic and industrial wiring installations and compares different wiring systems.
1. The document provides an overview of a training module on overhead line work. It covers power system structure, design principles of distribution lines, and installing/maintaining electrical equipment.
2. The objectives are to address distribution line problems, energize 33kV lines, develop awareness of installing/maintaining 33kV lines, and discuss insulation and equipment selection.
3. The target group are trainees in categories S1-S4 and W3-W6.
This is the simple ppt explaining about the main components of the power systems. especially we are determining the insulators and its types with real time pictures which are attractive,
The document discusses capacitive voltage transformers (CVTs). It describes CVTs as devices that step down extra high voltage signals for metering and protection purposes. CVTs consist of capacitors that divide the transmission line voltage, with an inductive element to tune the device to line frequency and a voltage transformer to further step down the voltage. CVTs are more economical than wound transformers for voltages over 100kV. CVTs can also be used for power line carrier communications and provide insulation between high and low voltage circuits.
This document provides information about electrical installation planning and wiring layout for multistorey buildings. It discusses how to create a wiring blueprint based on the building plan, including indicating loads, distribution boards, outlets and wiring routes. It also covers calculating the electrical load and number of circuits, sizing cables and conductors, and preparing an estimation of materials. Proper wiring layout allows electricians to easily install wiring according to the diagram. Distribution boards are also summarized, including types, installation procedures and protection devices.
The document discusses power insulators used in electricity transmission and distribution. It describes different types of insulators like pin, suspension, strain, stay, and shackle insulators. It also discusses properties, testing, causes of failure, and applications of insulators. Insulators are used to support electrical conductors and provide insulation between conductors and earth to prevent leakage currents. Common insulator materials include glass, porcelain, and plastic.
Underground cables have several advantages over overhead cables including better appearance, reduced damage from external factors like storms and lighting, lower maintenance costs, and fewer faults. Underground cables consist of one or more insulated conductors surrounded by protective layers. Key components include the conductor, insulation like paper or rubber, a metallic sheath, bedding, armor for protection, and an outer serving. Different types are used for various voltage applications up to extra high voltage cables over 33kV. Selection depends on factors like the number of cores needed, insulation material, and whether solid or pressure cables are required.
Electrical wiring is the process of connecting cables and wires from various devices like lights, fans, switches, and sockets to the main distribution board for continuous power supply. There are different types of electrical wiring systems including cleat wiring, wooden casing and capping wiring, CTS or TRS or PVC sheath wiring, lead sheathed or metal sheathed wiring, and conduit wiring. Conduit wiring can be surface or open conduit wiring or concealed or underground conduit wiring depending on where steel or PVC pipes are used to run the wires. Buildings come in different types including residential for personal houses, industrial for companies, and workshops for product manufacturing.
Overhead transmission lines transmit power using bare conductors suspended by towers, while underground cables transmit power below ground using insulated conductors inside protective casing. Underground cables are more expensive to install due to excavation costs but have fewer transmission losses and are unaffected by weather. Overhead lines are cheaper but more vulnerable to outages from lightning and damage. Underground cables can transmit up to 33kV while overhead lines can transmit higher voltages. Basic cable laying involves excavating trenches, laying cables in protective casing, backfilling trenches. There are different cable and transmission line types for varying voltages.
A Presentation based on Underground Cables Used In the Transmission And Distribution System.It is a topic covered in the syllabus of B.E. in Electrical Engineering in 5th semester Subject named "Electrical Power System" For more detail you can check the book "Electrical Power System" by Author V.K.Mehta and S.Chand Publication.
Liquids make excellent insulating materials due to their high density and heat transfer capabilities compared to gases. Common liquid insulators include transformer oils, silicone oils, and liquid nitrogen. While liquids can withstand very high dielectric strengths in theory, impurities like water, dust, ions, and dissolved gases reduce their actual breakdown strength. Liquids are useful as insulators in high voltage cables, capacitors, transformers, and circuit breakers, where they also act as coolants. The presence of even 0.01% water in oil can reduce its dielectric strength by 80%.
This document discusses different types of wires and cables used for power transmission. It describes common wire types like PVC wire and MICC wire and their advantages. It also discusses cable structure, classification based on insulation, conducting material and voltage rating. Cable termination and standard wire gauge for measuring current carrying capacity are also summarized.
A protective relay is a device that detects abnormal conditions in an electrical circuit, such as a fault, and triggers a circuit breaker to disconnect the faulty part of the circuit. There are several types of relays including definite time, differential, solid state, electromechanical, backup, current, voltage, and frequency relays. A differential relay compares currents on both sides of a power transformer to detect faults. Solid state relays have no moving parts, allowing for high-speed operation. Electromechanical relays use a spring, armature, electromagnet and contacts to close the circuit when energized. Protection schemes use primary and backup relays, with primary relays clearing faults fastest and backup relays removing more of
The document discusses one-line diagrams, which are simplified diagrams used in power systems to represent the essential components in a simplified graphical format. A one-line diagram shows the main components of a power system like generators, transmission lines, transformers, and loads using standardized symbols. It represents the paths of power flow through the system from generation to transmission to distribution. The diagram is structured to match the physical layout. Impedance and reactance diagrams are similar but represent electrical elements like generators and lines as impedance/reactance values instead of physical components. An example calculation of voltage drop in a transmission line is provided.
This document discusses transmission lines and overhead power lines. It describes different types of transmission lines like coaxial cable, microstrip, and twisted pair. It then covers overhead power lines, explaining that they transmit electricity over long distances using conductors like copper, steel, aluminum, and ACSR. The document also classifies overhead transmission lines by voltage and discusses conductor materials and their properties.
The document discusses different types of tests performed on high voltage insulators:
1) Type tests are conducted to determine if a particular insulator design is suitable for its intended purpose. These include withstand, dry one-minute, dry flashover, wet one-minute, and wet flashover tests.
2) Sample tests are performed on a few insulator samples and include mechanical loading, electro-mechanical, puncture voltage, and porosity tests.
3) Routine tests include mechanical, corrosion, and tensile tests to ensure insulators meet standards before use. Proper testing helps verify insulators can withstand high voltages and other stresses.
This document discusses earthing systems and the hazards of a broken neutral connection for a power transformer. It defines system earthing and equipment earthing, and explains that a broken neutral connection can cause overvoltage issues for the transformer and prevent protective relays from operating during a fault. The document also discusses the objectives and importance of proper earthing, including providing an alternative path for fault currents, ensuring safety from electric shocks, and maintaining system voltages. It provides examples of what can occur when a transformer's neutral connection to earth is broken.
Different types of insulation materialsinsulation4us
A crawl space installed under the house can make the home colder in the winter than a house built on a concrete slab. Mold and mildew are the common problems in a crawl space, so you need to guard your home against that as well. In order to keep the floors warmer and prevent mold and mildew from growing in the crawl space, requires installation of crawl space insulation. The insulation seals out drafts and prevents warm air from escaping out through the space. It is an efficient way to deal with the part of the house that is prone to dampness.
The document summarizes a seminar presentation on HVDC (high voltage direct current) transmission. Some key points:
- HVDC transmission has advantages over HVAC like lower transmission losses over long distances. The first HVDC link was between Gotland and mainland Sweden in 1954.
- HVDC uses direct current instead of alternating current to transmit electricity over long distances. It requires only two conductors instead of three. Losses are also lower compared to HVAC.
- HVDC transmission can be classified as homopolar, monopolar or bipolar depending on the conductor configuration. Early HVDC projects in India included the Rihand-Delhi and Chandrapur-Padghe lines which helped transmit
This is a small ppt made by me to describe about the basics of Insulators in HV , EHV transmission lines.Students who want to go through the basics for clearing the fundamentals they can go through this ppt. Thank you.
The document discusses types of underground power cables. It describes single-core and multi-core cables, their construction including conductor, insulation, sheathing, and armor. It discusses cable classification based on operating voltage and insulation material. Methods of cable laying and factors affecting reliability are also summarized. Cable testing methods include insulation resistance testing and capacitance testing to determine cable parameters.
Electrical wiring system - and estimation Mahfuz Sikder
The document discusses different types of electrical wiring systems used for domestic and commercial buildings. It covers various wiring methods like cleat wiring, wooden casing and capping wiring, lead sheathed wiring, conduit piping wiring and CTS/TRS sheathed wiring. For each method, it discusses the materials used, advantages, disadvantages and applications. The document also provides guidelines for domestic and industrial wiring installations and compares different wiring systems.
1. The document provides an overview of a training module on overhead line work. It covers power system structure, design principles of distribution lines, and installing/maintaining electrical equipment.
2. The objectives are to address distribution line problems, energize 33kV lines, develop awareness of installing/maintaining 33kV lines, and discuss insulation and equipment selection.
3. The target group are trainees in categories S1-S4 and W3-W6.
This is the simple ppt explaining about the main components of the power systems. especially we are determining the insulators and its types with real time pictures which are attractive,
The document discusses capacitive voltage transformers (CVTs). It describes CVTs as devices that step down extra high voltage signals for metering and protection purposes. CVTs consist of capacitors that divide the transmission line voltage, with an inductive element to tune the device to line frequency and a voltage transformer to further step down the voltage. CVTs are more economical than wound transformers for voltages over 100kV. CVTs can also be used for power line carrier communications and provide insulation between high and low voltage circuits.
This document provides information about electrical installation planning and wiring layout for multistorey buildings. It discusses how to create a wiring blueprint based on the building plan, including indicating loads, distribution boards, outlets and wiring routes. It also covers calculating the electrical load and number of circuits, sizing cables and conductors, and preparing an estimation of materials. Proper wiring layout allows electricians to easily install wiring according to the diagram. Distribution boards are also summarized, including types, installation procedures and protection devices.
The document discusses power insulators used in electricity transmission and distribution. It describes different types of insulators like pin, suspension, strain, stay, and shackle insulators. It also discusses properties, testing, causes of failure, and applications of insulators. Insulators are used to support electrical conductors and provide insulation between conductors and earth to prevent leakage currents. Common insulator materials include glass, porcelain, and plastic.
Underground cables have several advantages over overhead cables including better appearance, reduced damage from external factors like storms and lighting, lower maintenance costs, and fewer faults. Underground cables consist of one or more insulated conductors surrounded by protective layers. Key components include the conductor, insulation like paper or rubber, a metallic sheath, bedding, armor for protection, and an outer serving. Different types are used for various voltage applications up to extra high voltage cables over 33kV. Selection depends on factors like the number of cores needed, insulation material, and whether solid or pressure cables are required.
Electrical wiring is the process of connecting cables and wires from various devices like lights, fans, switches, and sockets to the main distribution board for continuous power supply. There are different types of electrical wiring systems including cleat wiring, wooden casing and capping wiring, CTS or TRS or PVC sheath wiring, lead sheathed or metal sheathed wiring, and conduit wiring. Conduit wiring can be surface or open conduit wiring or concealed or underground conduit wiring depending on where steel or PVC pipes are used to run the wires. Buildings come in different types including residential for personal houses, industrial for companies, and workshops for product manufacturing.
Overhead transmission lines transmit power using bare conductors suspended by towers, while underground cables transmit power below ground using insulated conductors inside protective casing. Underground cables are more expensive to install due to excavation costs but have fewer transmission losses and are unaffected by weather. Overhead lines are cheaper but more vulnerable to outages from lightning and damage. Underground cables can transmit up to 33kV while overhead lines can transmit higher voltages. Basic cable laying involves excavating trenches, laying cables in protective casing, backfilling trenches. There are different cable and transmission line types for varying voltages.
A Presentation based on Underground Cables Used In the Transmission And Distribution System.It is a topic covered in the syllabus of B.E. in Electrical Engineering in 5th semester Subject named "Electrical Power System" For more detail you can check the book "Electrical Power System" by Author V.K.Mehta and S.Chand Publication.
Liquids make excellent insulating materials due to their high density and heat transfer capabilities compared to gases. Common liquid insulators include transformer oils, silicone oils, and liquid nitrogen. While liquids can withstand very high dielectric strengths in theory, impurities like water, dust, ions, and dissolved gases reduce their actual breakdown strength. Liquids are useful as insulators in high voltage cables, capacitors, transformers, and circuit breakers, where they also act as coolants. The presence of even 0.01% water in oil can reduce its dielectric strength by 80%.
This document discusses different types of wires and cables used for power transmission. It describes common wire types like PVC wire and MICC wire and their advantages. It also discusses cable structure, classification based on insulation, conducting material and voltage rating. Cable termination and standard wire gauge for measuring current carrying capacity are also summarized.
A protective relay is a device that detects abnormal conditions in an electrical circuit, such as a fault, and triggers a circuit breaker to disconnect the faulty part of the circuit. There are several types of relays including definite time, differential, solid state, electromechanical, backup, current, voltage, and frequency relays. A differential relay compares currents on both sides of a power transformer to detect faults. Solid state relays have no moving parts, allowing for high-speed operation. Electromechanical relays use a spring, armature, electromagnet and contacts to close the circuit when energized. Protection schemes use primary and backup relays, with primary relays clearing faults fastest and backup relays removing more of
The document discusses one-line diagrams, which are simplified diagrams used in power systems to represent the essential components in a simplified graphical format. A one-line diagram shows the main components of a power system like generators, transmission lines, transformers, and loads using standardized symbols. It represents the paths of power flow through the system from generation to transmission to distribution. The diagram is structured to match the physical layout. Impedance and reactance diagrams are similar but represent electrical elements like generators and lines as impedance/reactance values instead of physical components. An example calculation of voltage drop in a transmission line is provided.
This document discusses transmission lines and overhead power lines. It describes different types of transmission lines like coaxial cable, microstrip, and twisted pair. It then covers overhead power lines, explaining that they transmit electricity over long distances using conductors like copper, steel, aluminum, and ACSR. The document also classifies overhead transmission lines by voltage and discusses conductor materials and their properties.
The document discusses different types of tests performed on high voltage insulators:
1) Type tests are conducted to determine if a particular insulator design is suitable for its intended purpose. These include withstand, dry one-minute, dry flashover, wet one-minute, and wet flashover tests.
2) Sample tests are performed on a few insulator samples and include mechanical loading, electro-mechanical, puncture voltage, and porosity tests.
3) Routine tests include mechanical, corrosion, and tensile tests to ensure insulators meet standards before use. Proper testing helps verify insulators can withstand high voltages and other stresses.
This document discusses earthing systems and the hazards of a broken neutral connection for a power transformer. It defines system earthing and equipment earthing, and explains that a broken neutral connection can cause overvoltage issues for the transformer and prevent protective relays from operating during a fault. The document also discusses the objectives and importance of proper earthing, including providing an alternative path for fault currents, ensuring safety from electric shocks, and maintaining system voltages. It provides examples of what can occur when a transformer's neutral connection to earth is broken.
Different types of insulation materialsinsulation4us
A crawl space installed under the house can make the home colder in the winter than a house built on a concrete slab. Mold and mildew are the common problems in a crawl space, so you need to guard your home against that as well. In order to keep the floors warmer and prevent mold and mildew from growing in the crawl space, requires installation of crawl space insulation. The insulation seals out drafts and prevents warm air from escaping out through the space. It is an efficient way to deal with the part of the house that is prone to dampness.
The document summarizes a seminar presentation on HVDC (high voltage direct current) transmission. Some key points:
- HVDC transmission has advantages over HVAC like lower transmission losses over long distances. The first HVDC link was between Gotland and mainland Sweden in 1954.
- HVDC uses direct current instead of alternating current to transmit electricity over long distances. It requires only two conductors instead of three. Losses are also lower compared to HVAC.
- HVDC transmission can be classified as homopolar, monopolar or bipolar depending on the conductor configuration. Early HVDC projects in India included the Rihand-Delhi and Chandrapur-Padghe lines which helped transmit
HVDC transmission involves transmitting power over long distances using direct current rather than alternating current. It became important as large amounts of power needed to be transmitted over long distances. The first HVDC link was established in 1954 between Sweden and an island. HVDC transmission has technical advantages like independent control of AC systems and faster changing of power flow. It also has economic advantages as the costs of DC lines and cables are lower than AC, and line losses are reduced. Various types of DC links exist including monopolar, bipolar, and homopolar configurations. Converter stations at each end are required to interface HVDC with AC systems.
1) HVDC transmission was first developed in the late 19th century by Rene Thury. Early systems used DC series generators and mechanical converters.
2) HVDC became more viable with the development of mercury arc valves in the 1950s and thyristor valves in the 1960s, allowing more efficient conversion between AC and DC.
3) HVDC is preferable to HVAC for long distance bulk power transmission, asynchronous connections, offshore wind connections, and other applications where HVDC has technical advantages over HVAC. Key components of HVDC systems include converters, smoothing reactors, filters, and the DC transmission line.
HVDC transmission involves converting AC power to DC, transmitting it through DC lines, and converting it back to AC. It has technical advantages over AC like lower transmission losses and asynchronous operation. Economically, DC lines and cables are cheaper to build than AC, and losses during transmission are lower. HVDC is used in long distance bulk power transmission and for undersea power cables due to its advantages over high voltage AC for these applications. Major HVDC projects in India transmit power between different regions of the country.
HVDC transmission systems allow for long distance and submarine power transmission with lower transmission losses compared to HVAC. HVDC uses converter stations to convert AC to DC for transmission and back to AC at the receiving end. Some key advantages are long distance transmission over 500km is more economical with HVDC, lower line losses, and ability to interconnect AC grids of different frequencies. HVDC is increasingly being used to integrate renewable energy sources like offshore wind farms.
The document discusses electrical hazards and safety measures. It begins by defining electrical hazards and categorizing them into electrical shock, burns, and blast effects. It then discusses the dangers of electricity to living tissue depending on factors like current, path through the body, contact location and duration. Conditions affecting shock severity and steps for helping an electrified person are outlined. The document recommends insulation, guarding, grounding and safe work practices to prevent accidents. Specific safety tips are provided such as using GFCI outlets, avoiding overloads, replacing damaged equipment, and calling emergency services for electrified individuals.
The document describes an experiment to test the insulating properties of different materials by measuring how quickly hot water cools when wrapped in tin foil, a plastic bag, newspaper, or a woolen sock. The student hypothesized that the woolen sock would keep the water warmest. They recorded the temperature of the water wrapped in each material after 5, 10, 20, and 30 minutes, finding a 4 degree Celsius difference between the best and worst insulators after 30 minutes. Their results supported the hypothesis, with the woolen sock keeping the water warmest and newspaper the coolest.
TOPIC 3.2- Effects to Insulation Materials.pptxMartMantilla1
This document discusses insulating materials, their properties, classifications, and applications. It describes the key electrical, thermal, chemical, and physical properties of insulating materials, including insulation resistance, dielectric strength, heat resistance, solubility, and mechanical strength. Insulating materials are classified as conductors, insulators, or semiconductors based on their resistivity. Common insulating materials include plastics, natural materials like mica and glass, and gases like nitrogen, hydrogen, and sulfur hexafluoride. The document explains how factors like temperature, moisture, and voltage affect an insulator's properties and breakdown voltage. It also provides guidelines for selecting insulating materials based on operating conditions, ease of shaping, availability, and cost.
The document discusses the characteristics and properties of insulating materials. It begins by introducing insulating materials and their importance. It then lists 16 characteristics of a good insulating material, including large insulating resistance, uniform viscosity, and resistance to deterioration. The document goes on to discuss the key properties of insulating materials, including their electrical, thermal, chemical, and mechanical properties. Some important electrical properties mentioned are resistivity, dielectric strength, power factor, and dielectric constant. Thermal properties discussed include specific heat, thermal conductivity, and heat aging. The document provides details on each of these properties.
The document discusses the properties and characteristics of good insulating materials. It outlines 16 characteristics a good insulating material should possess including large insulating resistance, high dielectric strength, and resistance to deterioration from chemicals, heat, and moisture. It then covers the key properties of insulating materials, specifically their electrical, thermal, chemical, and mechanical properties. Some important electrical properties discussed are resistivity, dielectric strength, power factor, and dielectric constant. Thermal properties covered include specific heat, thermal conductivity, and resistance to heat aging. The document provides details on each of these properties and their significance for insulating materials.
The document discusses the characteristics and properties of insulating materials. It begins by introducing insulating materials and their importance. It then lists 16 characteristics of a good insulating material, including large insulating resistance, uniform viscosity, and resistance to deterioration. The document goes on to discuss the key properties of insulating materials, including their electrical, thermal, chemical, and mechanical properties. Some important electrical properties mentioned are resistivity, dielectric strength, power factor, and dielectric constant. Thermal properties discussed include specific heat, thermal conductivity, and heat aging. The document also covers chemical properties like resistance to external chemicals and water, as well as mechanical properties such as density and hardness.
The document discusses the properties and characteristics of good insulating materials. It outlines 16 characteristics a good insulating material should possess including large insulating resistance, high dielectric strength, and resistance to deterioration from chemicals, heat, and moisture. It then covers the key properties of insulating materials, specifically their electrical, thermal, chemical, and mechanical properties. Some important electrical properties discussed are resistivity, dielectric strength, power factor, and dielectric constant. Thermal properties covered include specific heat, thermal conductivity, and resistance to heat aging. The document provides details on each of these properties and their significance for insulating materials.
The document discusses the properties and characteristics of good insulating materials. It begins by introducing insulating materials and their importance. It then lists 16 characteristics a good insulating material should possess, such as large insulating resistance, uniform viscosity, and resistance to deterioration. The document goes on to discuss the key properties of insulating materials, including their electrical, thermal, chemical, and mechanical properties. Some important electrical properties mentioned are resistivity, dielectric strength, power factor, and dielectric constant. Thermal properties discussed include specific heat, thermal conductivity, and heat aging. The document also covers chemical properties like resistance to external chemicals and water, as well as mechanical properties such as density, viscosity, and hardness.
This document discusses winding insulating materials used in transformers. It describes the key electrical properties insulating materials must have, including high electrical resistivity and high dielectric strength. It then classifies insulating materials into solid, liquid, and gaseous types based on their substance. It further classifies materials based on their maximum operating temperature. Common materials discussed include paper, cotton, mica, oils, and gases. Characteristics of good insulating materials and their application areas in transformers are also summarized.
Concept of insulation resistance & Polarization IndexHareshYadav4
This document discusses insulation resistance, which is the ability of electrical insulation to resist direct current. It defines the four components of current drawn by insulation when DC is applied: absorption, conduction, capacitance charging, and surface leakage currents. It also discusses the importance of polarization, factors that affect insulation resistance like temperature and moisture, recommended polarization index values, and minimum insulation resistance values according to IEEE and IS standards.
Insulation and Dielectric Breakdown Design Paper SM54Subhash Mahla
This document provides an overview of considerations for designing high voltage electrical insulation systems that will operate in sub-atmospheric environments. It discusses factors like operating voltage, temperature, pressure, and contamination that affect insulation performance. It also summarizes key insulation design challenges for different voltage ranges, like corona inception below 50V, flashover strength, breakdown of solid dielectrics, resistivity, and aging effects over time. The goal is to present general guidance on insulation material selection and design techniques to help ensure reliable high voltage systems.
This document discusses different types of insulators and insulating materials used in overhead and underground power transmission lines. It describes what insulators are and the key properties insulating materials should have like high resistivity and dielectric strength. The main types of insulators for overhead lines are pin, suspension, strain and shackle insulators. Early overhead lines used wood and glass insulators, then ceramic materials like porcelain were developed to withstand higher voltages. Now polymer and long rod insulators are common. Underground lines use insulating materials like rubber, impregnated paper, varnished cambric and PVC that can withstand moisture and mechanical stresses. Thicker cables are needed for underground transmission due to requirements for insulation and strength.
This document discusses various mechanisms for breakdown in solid dielectric materials. It describes intrinsic breakdown, which occurs at very high electric fields and depends on free electrons in the material. Electromechanical breakdown occurs when electrostatic forces exceed the material's mechanical strength. Breakdown can also be caused by treeing and tracking, where spark channels spread and form conductive paths. Thermal breakdown results from heat generated by dielectric losses exceeding heat dissipated from the material. Electrochemical breakdown involves chemical reactions like oxidation and hydrolysis that degrade insulating properties.
This document discusses various modes of heat transfer including conduction, convection, and radiation. It defines thermal insulation as materials that retard the flow of heat energy and discusses why insulation is necessary. It describes the main types of insulation materials as fibrous, cellular, and granular. It also covers temperature ranges for insulation, common forms that insulation takes, key thermal and mechanical/chemical properties of insulation materials, and provides examples of specific insulation types.
This document summarizes key concepts related to conductive and dielectric materials. It discusses mechanically processed forms of conductive materials and commonly used materials like copper. It also discusses high and low resistivity materials, contact materials, fusible materials, and carbon as a filament. Additionally, it covers dielectric constants, dielectric strength, polarization mechanisms, and factors affecting dielectric properties. Dielectric materials are classified and their uses discussed.
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1. INSULATING MATERIALS
SUBJECT: ELECTRICAL AND ELECTRONICS ENGG. MATERIALS
SEMESTER: THIRD
Presentation by :
Barjinder Singh
Lecturer, Electrical Engg.
Government Polytechnic College
G.T.B.GARH DISTT. MOGA
2. CONTENTS
• INTRODUCTION
• INSULATING MATERIALS, GENERAL
PROPERTIES
PHYSICAL PROPERTIES
ELECTRIAL PROPERTIES
THERMAL PROPERTIES
CHEMICAL PROPERTIES
MECHANICAL PROPERTIES
3. • INSULATING MATERIALS AND THEIR
APPLICATIONS
PLASTICS
NATURAL INSULATING MATERIALS
GASEOUS MATERIALS
4. INTRODUCTION
The materials which have very high
resistivity i.e. offers a very high resistance
to the flow of electric current. Insulating
materials plays an important part in
various electrical and electronic circuits. In
domestic wiring insulating material protect
us from shock and also prevent leakage
current.
So insulating material offers a wide range of
uses in engineering applications.
5. FACTORS AFFECTING SELECTION OF
AN INSULATING MATERIAL
1. Operating condition : Before selecting an
insulating material for a particular application
the selection should be made on the basis of
operating temperature, pressure and
magnitude of voltage and current.
2. Easy in shaping : Shape and size is also
important affect.
3. Availability of material : The material is easily
available.
4. Cost : Cost is also a important factor.
7. CONDUCTORS
The substances through which electric
current can flow easily are called
conductors.
e.g. Silver, gold, copper, aluminum etc.
Conductors have a large number of free
electrons. Generally metals have a large
number of free electrons, So all metals are
good conductors.
8. INSULATORS
Those substances through which electric
current cannot pass easily are called
insulators. e.g. Glass, Mica, dry Air,
Bakelite etc.
9. SEMICONDUCTORS
The substances whose resistivity lies
between the resistivity of conductors and
insulators are called semiconductors. e.g.
Germanium, Silicon, Carbon etc.
10. RESISTIVITY
Resistivity is the resistance between the two
opposite faces of a cube having each side equal
to one meter.
Resistivity of
CONDUCTORS 10-8
to 10-3
ohm-m
INSULATORS 1010-20
ohm-m
SEMICONDUCTORS 100-0.5 ohm-m
15. INSULATION RESISTANCE IS OF
TWO TYPES
• Volume insulation resistance
• Surface insulation resistance
16. VOLUME RESISTANCE &
RESISTIVITY
The resistance offered to current Iv
which flows through the material is
called volume insulation resistance. For
a cube of unit dimensions this is called
volume resistivity. As from A to C
18. SURFACE RESISTANCE
The resistance offered to current
which flows over the surface of
the insulating material is called
surface insulation resistance. As
from A to B and then B to C
25. AGEING
Ageing reduces the insulation
resistance. As age of insulation
material is increased the insulation
resistance decreases.
26. DIELECTRIC STRENGTH
Dielectric strength is the minimum
voltage which when applied to an
insulating material will result in the
destruction of its insulating properties.
Electrical appliances/apparatus is
designed to operate within a defined
range of voltage.
27. If the operating voltage is increased
gradually at some value of voltage, the
breakdown of the insulating materials
will occur.
The property which attributes to such
type of break down is called the
dielectric strength.
28. e.g. dielectric strength of mica is 80kV/mm.
It means if the voltage applied across 1mm
thick sheet of mica becomes 80kV mica
will lose its insulating properties and
current will start passing through mica
sheet.
In other words dielectric strength of an
insulating material is the maximum
potential gradient that the material can
withstand without rupture
34. SUPPLY FREQUENCY
As the frequency of the applied
voltage increases the dielectric strength
of the insulating material also
increases.
35. DIELECTRIC CONSTANT
The ratio of capacity of storing
the electric charge by an
insulating material to that of air is
called dielectric constant of the
material.
36. Every insulating material has the property
of storing electric charge ‘Q’ , when a
voltage V is applied across it. The charge is
proportional to the voltage applied i.e.
QαV and we get Q=CV
Where C is the capacitance of the capacitor
which was formed by placing the material
between the conductors across which
voltage is applied.
37. The capacitance of the capacitor will
change if the air between the plates of a
capacitor is replaced by an insulating
material acting as a dielectric.
The property of insulating materials
that causes the difference in the value
of capacitance, physical dimensions
remaining same, is called the dielectric
constant or permittivity
38. DIELECTRIC LOSS
Electrical energy absorbed by the insulating
material and dissipated in the form of heat
when an alternating voltage is applied
across it is called dielectric loss.
When a perfect insulation is subjected to
alternating voltage it is like applying like
alternating voltage to a perfect capacitor. In
such a case there is no consumption of
power.
39. Only vacuum and purified gases
approach this perfection. In such a case
the charging current would lead the
applied voltage by 90 degree exactly.
This would mean that there is no power
loss in the insulation.
40. In most of the insulating materials, that is not the
case. There is a definite amount of dissipation
of energy when an insulator is subjected to
alternating voltage. This dissipation of energy is
called dielectric loss .
In practice, the leakage current does not lead
applied voltage by exactly 90 degree. The phase
angle is always less than 90 degree. The
complementary angle δ=90-θ is called dielectric
loss angle.
45. APPLIED VOLTAGE
Dielectric loss rises with rise in the
applied voltage. This loss is one factor
in limiting the operating voltage of
underground cables generally to 100
kV.
46. THERMAL PROPERTIES
• HEAT RESISTANCE
•PERMISSIBLE TEMPERATURE RISE
•EFFECT OF OVERLOADING ON THE LIFE
OF AN ELECTRICAL APPLIANCE
•THERMAL CONDUCTIVITY
47. HEAT RESISTANCE
This is general property of insulating
material to withstand temperature variation
within desirable limits, without damaging
its other important properties.
If an insulator has favorable properties at
ambient temperature but, if it is not able to
retain these, it is not a good insulator.
48. The insulator which is capable of
withstanding higher temperature
without deterioration of its other
properties can be used for operation for
such higher temperature.
50. CLASSIFICATION ON THE BASIS OF
OPERATING TEMPERATURE
CLASS ‘Y’ INSULATION - 90 ºC
CLASS ‘A’ INSULATION - 105 ºC
CLASS ‘E’ INSULATION - 120 ºC
CLASS ‘B’ INSULATION - 130 ºC
CLASS ‘F’ INSULATION - 155 ºC
CLASS ‘H’ INSULATION - 180 ºC
CLASS ‘C’ INSULATION - >180 ºC
51. CLASS ‘Y’ INSULATION
Material if un-impregnated fall in this
category with operating temperature up
to 90 ºC. e.g. paper, cardboard, cotton,
poly vinyl chloride etc.
53. CLASS ‘E’ INSULATION
Insulation of this class has operating
temperature of 120 ºC. Insulators used
for enameling of wires fall in this
category. e.g. pvc etc.
54. CLASS ‘B’ INSULATION
Impregnated materials fall in class B
insulation category with operating
temperatures of about 130 ºC. e.g.
impregnated mica, asbestos, fiber glass
etc.
55. CLASS ‘F’ INSULATION
Impregnated materials, impregnated or
glued with better varnises e.g.
polyurethane, epoxides etc. fall in this
category with operating temperature of
about 155 ºC.
56. CLASS ‘H’ INSULATION
Insulating materials either impregnated
or not, operating at 180 ºC fall in this
category. e.g. fiberglass, mica,
asbestos, silicon rubber etc.
57. CLASS ‘C’ INSULATION
Insulators which have operating
temperatures more than 180 ºC fall in
class C insulation category. e.g. glass,
ceramics, poly tera fluoro ethylene,
mica etc.
59. There is always some recommended
operating temperature for an insulator. The
operating temperature has a bearing on the
life of the concerned apparatus. A thumb
rule suggested by many experts is that life
of insulator is halved for 8-10 degree
centigrade rise above the recommended
operating temperature for a given
apparatus.
60. EFFECT OF OVERLOADING ON THE
LIFE OF AN ELECTRICAL APPLIANCE
AND
ELECTRO THERMAL BREAK DOWN
IN SOLID DIELECTRICS
61. Insulators can withstand overloading
within permissible limits for short
period of time. Continuous overloading
ultimately results in the breakdown of
the insulating materials. Consider an
underground cable under operation.
This cable is recommended for
operation with certain limitation of
voltage and current. Suppose voltage is
increased .
62. If the involved insulating material is able to
withstand the higher voltage stress, the
change will cause increase of dielectric
losses that will increase heat generation .
So, the temperature of the insulation will
further increase. If the applied overvoltage
is withdrawn, the damage may not be
permanent and the cable will cool down
with time and start operating normally.
63. If overvoltage is not removed, the cycle of
temperature rise goes on and ultimately the
insulator starts losing its insulating properties,
ultimately breakdown of the insulating material
will occur and the cable will be permanently
damaged.
Secondly if load current in the cable is increased
I2
R losses will increase, resulting once again in
increased heat generation. And if overloading
maintained, will ultimately result in breakdown
of the insulating material.
64. THERMAL CONDUCTIVITY
Heat generated due to I2
R losses and
dielectric losses will be dissipated through
the insulator itself. How effectively this
flow of heat takes place, depends on the
thermal conductivity of the insulator. An
insulator with better thermal conductivity
will not allow temperature rise because of
effective heat transfer through it to the
atmosphere.
66. SOLUBILITY
In certain application insulation can be
applied only after it is dissolved in some
solvents . In such cases the insulating
material should be soluble in certain
appropriate solvent. If the insulating
material is soluble in water then moisture in
the atmosphere will always be able to
remove the applied insulation and cause
break down.
67. CHEMICAL RESISTANCE
Presence of gases, water, acids , alkalis
and salts affects different insulators
differently. Chemically a material is a
better insulator if it resist chemical
action.
Certain plastic are found approaching
this condition. Consequently their use
is very much increase.
68. WEATHERABILITY
Insulators come in contact with
atmosphere both during manufacture or
operation. The contact of insulation
with atmosphere is often so complete
that even the less chemically aggressive
atmosphere can prove a threat to the
smooth running of apparatus.
69. HYGROSCOPICITY
The property of insulating material by
virtue of which it absorbs moisture.
The insulating material should be non-
hygroscopic. The absorption of
moisture reduces the resistivity of the
insulator.
71. MECHANICAL STRENGTH
The insulating material should have
high mechanical strength to bear the
mechanical stresses and strains during
operation.
Temperature and humidity are the main
factors which reduce the mechanical
strength of insulating materials.
72. POROSITY
A material having very small holes in it
is called a porous material. Insulator
absorbs moisture if it is porous, which
reduces its resistivity as will as
mechanical strength. Porous material
are impregnated with varnishes or
resins to fill their pores which makes
them non-porous thus better insulating
materials.
77. There are thousand of insulating materials
available in the market . Insulation
technology is one of those few branches
where the number of materials available for
a particular application are more than one.
Any special requirement can be served by
some special material.
79. Operating temperature, pressure, operating
voltage and current are to be considered for
the selection of a particular material.
OPERATING CONDITION
80. EASY TO SHAPE
For ease of fabrication the material
should be easy to shape.
82. For cost-effectiveness of the insulating
products the material should not have a
very high cost compared to the other
options available for the same use.
COST
84. Plastics are basically hydrocarbons i.e. they
contain hydrogen and carbon as their
essential components.
Plastics are found in nature are called
Natural Plastics. While man made plastics
are called Synthetic Plastics and they are
classified accordingly.
PLASTICS
85.
86. The plastics obtained directly from nature
i.e. from either plants or animals are called
natural plastics. The properties of most of
natural plastics are not very good from the
point of view of their use as insulators. But
a few still find applications in electrical
industry as insulators.
NATURAL PLASTICS
95. Used in the manufacturing of mica
tapes as a binding material.
APPLICATIONS
96. The plastics obtained by a chemical
process called polymerization, are
called synthetic plastics.
SYNTHETIC PLASTICS
97. THERMOSETTING PLASTICS
The plastics which lose their properties
when cooled after melting and cannot
be reshaped are called thermosetting
plastics.
98. PROPERTIES
Made by Condensation Polymerization.
Cross linked chains of molecules.
Hard and Rigid.
Higher molecular weight.
Low hygroscopicity.
Good dielectric Strength.
100. THERMOPLASTICS
The plastics which retain their
properties even when cooled after
melting and can be reshaped are called
thermosetting plastics.
101. PROPERTIES
Made by Additional system of Polymerization
No Cross linked chains of molecules.
Less Flexible but Mechanically stronger.
Low molecular weight.
Highly Hygroscopic.
Poor Dielectric Properties.
106. APPLICATIONS
Capacitors.
Windings of DC machines.
Non-Sticking Layer on electric Irons,
Hot Plates etc.
Cable insulator for cables operating at
high temperature.
117. POLYVINYAL CHLORIDE
Polymer of Vinyl Chloride. Polymerized
in the presence of a catalyst at 50 ºC.
Vinyl Chloride is obtained by the
reaction of acetylene with hydro chloric
acid.
118. H H H H H H H H
| | | | | | | |
--- C---- C---- C---- C---- C---- C---- C---- C ---
| | | | | | | |
Cl H Cl H Cl H Cl H
121. NATURAL INSULATING
MATERIALS
Mica and mica products
Asbestos and asbestos products
Ceramic materials (porcelain)
Glass and glass products
Cotton/ Silk / Jute
122. Paper (dry and impregnated)
Rubber
Mineral and insulating oil
Insulating varnishes
Enamels for winding wires
123. MICA AND MICA PRODUCTS
Mica is an inorganic mineral . It is one of the
best natural insulating materials available.
It is one of the oldest insulating material of out-
standing performance. India fortunately claims
the biggest reserves of mica in world.
About 80% of total World requirement of mica
for electrical industry is furnished by India.
124. MICA
Chief sources of supply are India,
Brazil and U.S.A. But the best quality
is available in India. The basic
composition is KH2Al3(SiO4)3.
125. PROPERTIES
Strong , tough and less flexible.
Colorless, Yellow, Silver or Green.
Very good Insulating properties.
High resistance.
Not affected by alkalis.
132. SYNTHETIC MICA
The development of synthetic mica took
place during world war II.
Although synthetic mica possesses many
technical defects of natural mica.
135. MANUFACTURED MICA
When mica flakes are held together
with adhesive the product is called
mica plate. The binding material is
about 20%.The binding materials are
shellac, epoxy and silicon resins etc.
136. Commutators of DC motors and
generators.
Insulation for armature and field coils.
Heating appliances.
Transformers.
APPLICATIONS
141. APPLICATIONS
It is used in low voltage work in the form
of pipe, tape, cloth and board.
Coil winding and insulating end turns.
Arc Barriers in Circuit Breakers and
Switches.
Transformers.
142. INDUSTRIAL ASBESTOS
PRODUCTS
Asbestos claims its utility in engineering
applications because of crystalline structure and
structural stability at high temperature.
However it has limitation because of low tensile
strength, high dielectric loss and sensitivity
towards moisture.
Some of the asbestos are as follows:
147. ASBESTOS CEMENT
About 20% asbestos fiber and 80%
Portland cement are the main
constituents of asbestos cement.
Impregnated asbestos cement products
are used to overcome its hygroscopic
nature.
149. These cements find their use in
switch panel construction and in
arcing devices.
APPLICATIONS
150. CERAMICS MATERIALS
Ceramics are materials made by high
temperature firing treatment of natural
clay and certain organic matters.
Structurally ceramics are crystals
bonded together. Other materials used
with clay in different type of ceramics
are Quartz, Talc, Magnetite etc.
151. .
Hard, strong and dense.
Not affected by chemical action Stronger
in compression than tension
Stability at high temperatures
Excellent dielectric properties.
Weak in impact strength.
PROPERTIES
156. PORCELAIN
Porcelain are basically clays and quartz
embedded in glass matrix. When used
as insulators glazing is done i.e. a thin
layer of glass is glazed over the
insulator.
162. GLASS
It is normally transparent , brittle and hard. It is
insoluble in water and the usual organic
solvents.
Glass find its use in electrical industry because
of its low dielectric loss, slow aging and good
mechanical strength.
Glass has its limitations because it is not easy to
manufacture and is dense and heavy.
163. APPLICATION
Molded devices such as electrical bushings,
fuse bodies, insulators.
Capacitor.
Radio and television tubes
Laminated boards.
Lamps/ Fluorescent Tubes
164. COTTON
Cotton is natural fibrous material
obtained from plants. It is used as
insulator only after impregnation
with oils or varnishes, which reduce
its hygroscopicity.
173. The source of dry paper is cellulose
obtained mainly from wood. It is
obtained by pulping the wood first and
then passing it through the rollers to
give it the final shape.
DRY PAPER
176. To improve the properties of dry
paper it is impregnated with oils or
varnishes.
IMPREGNATED PAPER
177. It has better properties then the dry
paper in terms of mechanical strength,
chemical resistance, dielectric constant,
operating temperature, hygroscopicity and
dielectric loss.
PROPERTIES
179. Varnishes are obtained by dissolving
the materials in oil or alcohol. They
are used mainly for impregnation,
surface coating and as adhesives.
VARNISHES
182. RUBBER
Natural rubber is obtained from the
milky sap of trees. It finds limited
applications in the field of engineering.
The reasons are
Rubber is a material which is
stretchable to more than twice its
original length without deformation.
185. APPLICATIONS
It finds limited use in covering wires,
conductors etc for low voltage
operations.
Gloves, Rubber Shoes.
186. Increased sulphur contents and
extended vulcanization treatment
gives rigid rubber product.
HARD RUBBER
187. Good electrical properties
High tensile strength.
Maximum permissible operating
temperature is 60 º C.
Continued exposure to sun is harmful.
PROPERTIES
191. PROPERTIES
Silicon rubber posses thermal conductivity twice
than natural rubber
Their operating temperature range is very wide
stretching from -600
C to 1500
C.
Tensile strength of these materials is low but
stability at high temperatures is remarkable.
They exhibit good flexibility at low temperature.
Silicon rubber are exceptionally good electrical
properties.
194. AIR
Like other insulating gases , the dielectric
constant of the air increases linearly with
increasing gas pressure. Air acts as an
insulation in many electrical applications
in addition to the solid or liquid insulating
materials provided. Common examples are
overhead transmission lines, air condensers,
plugs, switches, various electrical machines
and apparatus etc.
195. HYDROGEN
Hydrogen is rarely used as an insulator. It
is used for cooling purposes in electrical
machines. liquid insulating materials
provided.
Common examples are overhead
transmission lines, air condensers, plugs,
switches, various electrical machines and
apparatus etc.
196. NITROGEN
Nitrogen is commonly used as an insulator
in electrical equipment. In many
applications it is for both electrical and
chemical purposes.
In many high voltages applications air is
replaced by nitrogen to prevent oxidation of
the other insulating materials
198. Remarkably high dielectric strength.
Non inflammable .
Cooling property is superior to those of air
and nitrogen. At increase pressure its
dielectric strength increases and may even
become equal to that of transformer oil.
PROPERTIES
199. Disadvantages
To have high dielectric strength this gas
must be used under high pressure which
needs a scaled tank construction capable of
withstanding the pressure over the whole
temperature range of its commercial use.
The presence of sulfur in the molecule
under some condition involve corrosion of
the contacting surfaces.