This document provides information about transformers and their components. It discusses how transformers work using electromagnetic induction to transfer energy between circuits without a direct electrical connection. The key components of a transformer are described, including the magnetic core made of silicon steel, the windings, insulation and cooling using mineral oil. Ideal transformer theory is also covered, explaining voltage and current ratios based on winding turns.
This document summarizes a research paper on implementing smooth transitions between optimal control modes in a switched reluctance motor (SRM). It begins with introductions to SRM technology and an overview of the paper contents. It then covers the operating principles, characteristics, control strategies, and modes of operation of SRMs. The document describes the development of a Simulink model for a proposed optimal controller, including subsystems for pulse width modulation and single pulse control. Simulation results are presented and analyzed for no-load operation, with load, and under speed and torque dynamics. The analysis shows the controller varies turn-on and turn-off angles optimally under different operating conditions to reduce ripple and enable smooth transitions between control modes. The conclusion
This document discusses the testing and maintenance of power transformers. It outlines the various routine tests performed on transformers according to standards, including winding resistance measurement, insulation resistance measurement, high voltage tests, no load and load loss measurements. It also describes type tests such as lightning impulse and short circuit tests. Finally, it discusses the importance of preventive maintenance through regular checks of oil levels, insulation resistance, bushings, connections and other components.
1) Synchronous machines have a rotor supplied by an external DC source that produces a rotating magnetic field. This induces a voltage in the stator windings.
2) The rotor can have either salient or non-salient poles and is laminated to reduce eddy currents. DC power is supplied to the rotor via slip rings and brushes or a brushless exciter.
3) An equivalent circuit model represents the internal generated voltage and accounts for armature reaction, inductance, and resistance effects on the terminal voltage.
This presentation provides an overview of power transformers. It discusses that power transformers are static machines that transform power from one circuit to another without changing frequency, and are used between generators and distribution circuits. It then describes the typical power ratings of small, medium, and large power transformers. The main components of power transformers are then outlined, including bushings, the core and winding, conservator tank, breather and silica gel, cooling tubes, tap changer, transformer oil, and Buchholz relay. The functions of these key components are explained at a high level.
The document discusses synchronous generators and their operation. It covers:
- The two reaction theory which separates the armature mmf into direct and quadrature axis components.
- How phasor diagrams can be used to represent the direct and quadrature axis reactances (Xd and Xq).
- The slip test method to measure Xd and Xq by taking voltage-to-current ratios with the armature mmf aligned to each axis.
- Important cautions for the slip test including keeping slip extremely low to avoid errors from damper windings or open circuit voltages reaching dangerous levels.
This document provides guidance on setting calculations for transformer differential protection. It discusses examining CT performance, calculating winding "tap" values, and determining pickup points for the 87T, 87H, and 87GD elements. Key steps include checking CT and relay ratings, selecting tap settings, setting the 87T minimum pickup and slope settings, setting harmonic restraint values, and setting the 87H unrestrained high set differential pickup and delay. The goal is to provide high-speed protection while avoiding misoperation during conditions like inrush current.
This document summarizes a research paper on implementing smooth transitions between optimal control modes in a switched reluctance motor (SRM). It begins with introductions to SRM technology and an overview of the paper contents. It then covers the operating principles, characteristics, control strategies, and modes of operation of SRMs. The document describes the development of a Simulink model for a proposed optimal controller, including subsystems for pulse width modulation and single pulse control. Simulation results are presented and analyzed for no-load operation, with load, and under speed and torque dynamics. The analysis shows the controller varies turn-on and turn-off angles optimally under different operating conditions to reduce ripple and enable smooth transitions between control modes. The conclusion
This document discusses the testing and maintenance of power transformers. It outlines the various routine tests performed on transformers according to standards, including winding resistance measurement, insulation resistance measurement, high voltage tests, no load and load loss measurements. It also describes type tests such as lightning impulse and short circuit tests. Finally, it discusses the importance of preventive maintenance through regular checks of oil levels, insulation resistance, bushings, connections and other components.
1) Synchronous machines have a rotor supplied by an external DC source that produces a rotating magnetic field. This induces a voltage in the stator windings.
2) The rotor can have either salient or non-salient poles and is laminated to reduce eddy currents. DC power is supplied to the rotor via slip rings and brushes or a brushless exciter.
3) An equivalent circuit model represents the internal generated voltage and accounts for armature reaction, inductance, and resistance effects on the terminal voltage.
This presentation provides an overview of power transformers. It discusses that power transformers are static machines that transform power from one circuit to another without changing frequency, and are used between generators and distribution circuits. It then describes the typical power ratings of small, medium, and large power transformers. The main components of power transformers are then outlined, including bushings, the core and winding, conservator tank, breather and silica gel, cooling tubes, tap changer, transformer oil, and Buchholz relay. The functions of these key components are explained at a high level.
The document discusses synchronous generators and their operation. It covers:
- The two reaction theory which separates the armature mmf into direct and quadrature axis components.
- How phasor diagrams can be used to represent the direct and quadrature axis reactances (Xd and Xq).
- The slip test method to measure Xd and Xq by taking voltage-to-current ratios with the armature mmf aligned to each axis.
- Important cautions for the slip test including keeping slip extremely low to avoid errors from damper windings or open circuit voltages reaching dangerous levels.
This document provides guidance on setting calculations for transformer differential protection. It discusses examining CT performance, calculating winding "tap" values, and determining pickup points for the 87T, 87H, and 87GD elements. Key steps include checking CT and relay ratings, selecting tap settings, setting the 87T minimum pickup and slope settings, setting harmonic restraint values, and setting the 87H unrestrained high set differential pickup and delay. The goal is to provide high-speed protection while avoiding misoperation during conditions like inrush current.
Internship report from my internship at VVC transformer manufacturing company in Bangalore.We did this internship in the third year of our electrical and electronics engineering under VTU.
Project on Transformer Design | Electrical Machine DesignJikrul Sayeed
Transformer Design | Core Design | Full Design | EE 3220 Electrical Machine Design
EE-3220
Core Design
Window Dimensions
Yoke Design
Overall Dimensions of Frame
Low Voltage Winding
High Voltage Winding
Resistance
Leakage Reactance
Regulation
Losses
Core Loss
Efficiency
No Load Current
Tank
Project on Transformer Design
The document lists the main parts of a transformer as: metallic core, holding frame, winding, on load tap changer, bushings and terminals, radiator wings/cooling tubs, breather, Buchholz relay, explosion valve, control panel, and tank. It provides the names of the core components that make up a transformer.
This document discusses overvoltage phenomena and insulation coordination in high voltage engineering. It covers several topics:
1) Natural causes of overvoltages like lightning and the mechanisms behind lightning strokes.
2) Classification of transmission lines and the behavior of traveling waves at transition points like reflections and successive reflections shown through lattice diagrams.
3) Causes of overvoltages from switching surges during circuit operations, system faults, and abnormal conditions. Characteristics of switching surges and issues in extra high voltage systems are described.
4) Methods to control overvoltages including stepped energization of lines, phase controlled circuit breakers, and drainage of trapped charges. Protective devices like expulsion gaps, protector tubes
This document summarizes the design of a 150 KVA, 11KV/0.415KV distribution transformer with the following key details:
1. The core has a cross-sectional area of 24.82 cm2 with a diameter of 211mm. The flux density in the core is 1.0T and in the yoke is 0.833T.
2. The low voltage winding uses a cylindrical design with 44 turns per phase and a current density of 1.98A/mm2.
3. The high voltage winding uses a crossover design with 2121 total turns to provide a 5% tapping. It has a maximum inter-layer voltage of 143V.
4. The overall
The document discusses the construction and operation of synchronous generators. It describes how a synchronous generator works by applying a DC current to the rotor to create a rotating magnetic field, which induces a 3-phase voltage in the stator windings. It also discusses the rotor, field windings, armature windings, brushless excitation systems, equivalent circuits, phasor diagrams, and the effects of load changes on generators operating alone or connected in parallel.
The document provides details about the construction and components of a DC generator, including:
1) It describes the main constructional features such as the magnetic frame, pole cores, field coils, armature core, armature winding, commutator, and brushes.
2) It explains the functions of these different components and how they enable the machine to operate as a generator or motor.
3) Diagrams and illustrations are provided to supplement the explanations of the components and their roles in the machine.
This document discusses various protection schemes for alternators, including differential protection, differential protection for alternators with high resistance grounding, negative phase sequence protection, balanced earth fault protection, and overcurrent protection. It describes how each protection scheme detects faults or unbalanced loading conditions in the alternator. Differential protection compares currents on each side of the alternator winding and trips if they are unequal due to an internal fault. Other schemes like negative phase sequence and earth fault protection are used to detect unbalanced or ground faults that may not be caught by differential protection.
1. Transformers have on-load and off-load tap changers that allow adjusting the transformer's output voltage without interrupting the load current. On-load tap changers can adjust voltage while energized using fast-acting switches, while off-load tap changers require de-energizing the transformer to change taps.
2. On-load tap changers are commonly used in power generation and distribution transformers to control voltage as load and line conditions vary. They monitor voltage and raise or lower taps using an automatic voltage regulator. Off-load tap changers are typically used in solar and wind projects where the generator voltage is low-voltage.
3. The on-load tap changer maintains uninterrupted
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,
This document discusses optimal power flow (OPF) analysis, which determines optimal settings for control variables like generator outputs and transformer taps to minimize objectives like power losses while satisfying operating constraints. The key aspects covered include: the differences between standard load flow and OPF; examples of optimization problems; common objective functions and control variables used in OPF; and the use of an OPF study case editor to set up optimization problems.
This document discusses special electrical machines, specifically permanent magnet synchronous motors (PMSM). It describes PMSM as a brushless DC motor with permanent magnets on the rotor that create magnetic poles instead of a field winding. The document outlines the basic construction and working principle of PMSM, noting that a rotating magnetic field from the stator interacts with the permanent rotor magnets to produce torque. Applications mentioned include servo drives, robotics, traction systems, and railway transportation.
Three Phase Transformer
Presented by:
Rizwan Yaseen 2017-EE-432
Zeeshan Saeed 2017-EE-414
Muhammad Hamad 2017-EE-404
Muhammad Zeeshan 2017-EE-402
A three phase transformer is made of three sets of primary and secondary windings wound around the legs of a common iron core. It allows for higher transmission voltages using lower amperage wiring. The core can be constructed as either a core type or shell type configuration. A three phase transformer works by inducing secondary voltages from the three phase primary voltages to maintain the proper phase relationships for power distribution.
A transformer is a device that changes alternating current (ac) electric power at one voltage level to ac electric power at another voltage level through the action of a magnetic field. An ideal transformer is a lossless device that transfers power efficiently between its two windings. A real transformer is modeled using an equivalent circuit that accounts for power losses, including copper losses, eddy current losses, hysteresis losses, and leakage fluxes. The parameters of the equivalent circuit can be determined experimentally using open-circuit and short-circuit tests.
This document provides a 24 step process for designing a 250 VA, 250 Watt isolation transformer with specifications including 230 V input and output voltages, 95% efficiency, and 1.6 T flux density. Key details include:
1) Total power is calculated to be 513.16 Watts accounting for losses.
2) Core geometry is calculated to be 18.04 cm^5 and the closest lamination is EI-150.
3) Primary and secondary winding properties like number of turns and copper losses are calculated based on the specifications.
4) Total copper loss is calculated to be 8.747 Watts and voltage regulation is 3.5%, meeting the specified 5% maximum.
The document discusses different types of conductors used in power transmission. It describes the major materials used which include copper, aluminum, and aluminum alloys. The major types of conductors are identified as AAC (All Aluminum Conductor), AAAC (All Aluminum Alloy Conductor), ACSR (Aluminum Conductor Steel Reinforced), and ACAR (Aluminum Conductor Aluminum Alloy Reinforced). Key factors to consider in conductor selection include physical properties of the materials, mechanical characteristics, electrical performance, and cost. The design of conductors involves tradeoffs between these various factors.
This document summarizes the summer training report submitted by four students from Amritsar College of Engineering & Technology at the Punjab State Power Corporation Limited Transformer Repair Workshop in Amritsar. The workshop repairs damaged transformers to save costs compared to the private sector. It has two main circles and aims to repair 120 units per month. The report describes the workshop organization and sections for washing, repairing, drying, assembling, testing and storing transformers. It also explains transformer components, types, workings, efficiency tests and applications.
Overhead line insulators are used to electrically isolate power line conductors from each other and supporting structures. They protect transmission lines from over-voltages caused by lightning and switching. The most common insulator materials are porcelain and glass. Pin insulators are used for voltages up to 33kV, while suspension insulators are preferred for higher voltages as they can be scaled more easily. Proper insulator selection and arrangement is needed to achieve uniform voltage distribution across the insulator string. Sag in overhead lines must be properly calculated to limit conductor tension within safe levels while minimizing material usage and clearance heights.
The document discusses the working of transformers. It explains that a transformer is a static device that changes alternating current (AC) voltage levels through magnetic induction between two coils. The changing current in the primary coil produces a magnetic field that is concentrated in the secondary coil, inducing a voltage across it. Transformers consist of magnetic cores and windings, and can be classified by phase (single or three phase), core type (core or shell), or cooling system (self-cooled, oil-cooled, air-cooled). Transformers operate on the principle of mutual induction to increase or decrease voltages for applications.
Presentation about transformer and its types M Tahir Shaheen
- A transformer is a static device that changes electrical power at one voltage level into electrical power at another voltage level through magnetic induction. It does not change the frequency.
- There are two main types of transformers: step-up transformers, which increase voltage, and step-down transformers, which decrease voltage. This is achieved by varying the number of turns in the primary and secondary coils.
- Transformers work on the principle of mutual induction. A changing magnetic field induced by alternating current in the primary coil induces a voltage in the secondary coil.
Internship report from my internship at VVC transformer manufacturing company in Bangalore.We did this internship in the third year of our electrical and electronics engineering under VTU.
Project on Transformer Design | Electrical Machine DesignJikrul Sayeed
Transformer Design | Core Design | Full Design | EE 3220 Electrical Machine Design
EE-3220
Core Design
Window Dimensions
Yoke Design
Overall Dimensions of Frame
Low Voltage Winding
High Voltage Winding
Resistance
Leakage Reactance
Regulation
Losses
Core Loss
Efficiency
No Load Current
Tank
Project on Transformer Design
The document lists the main parts of a transformer as: metallic core, holding frame, winding, on load tap changer, bushings and terminals, radiator wings/cooling tubs, breather, Buchholz relay, explosion valve, control panel, and tank. It provides the names of the core components that make up a transformer.
This document discusses overvoltage phenomena and insulation coordination in high voltage engineering. It covers several topics:
1) Natural causes of overvoltages like lightning and the mechanisms behind lightning strokes.
2) Classification of transmission lines and the behavior of traveling waves at transition points like reflections and successive reflections shown through lattice diagrams.
3) Causes of overvoltages from switching surges during circuit operations, system faults, and abnormal conditions. Characteristics of switching surges and issues in extra high voltage systems are described.
4) Methods to control overvoltages including stepped energization of lines, phase controlled circuit breakers, and drainage of trapped charges. Protective devices like expulsion gaps, protector tubes
This document summarizes the design of a 150 KVA, 11KV/0.415KV distribution transformer with the following key details:
1. The core has a cross-sectional area of 24.82 cm2 with a diameter of 211mm. The flux density in the core is 1.0T and in the yoke is 0.833T.
2. The low voltage winding uses a cylindrical design with 44 turns per phase and a current density of 1.98A/mm2.
3. The high voltage winding uses a crossover design with 2121 total turns to provide a 5% tapping. It has a maximum inter-layer voltage of 143V.
4. The overall
The document discusses the construction and operation of synchronous generators. It describes how a synchronous generator works by applying a DC current to the rotor to create a rotating magnetic field, which induces a 3-phase voltage in the stator windings. It also discusses the rotor, field windings, armature windings, brushless excitation systems, equivalent circuits, phasor diagrams, and the effects of load changes on generators operating alone or connected in parallel.
The document provides details about the construction and components of a DC generator, including:
1) It describes the main constructional features such as the magnetic frame, pole cores, field coils, armature core, armature winding, commutator, and brushes.
2) It explains the functions of these different components and how they enable the machine to operate as a generator or motor.
3) Diagrams and illustrations are provided to supplement the explanations of the components and their roles in the machine.
This document discusses various protection schemes for alternators, including differential protection, differential protection for alternators with high resistance grounding, negative phase sequence protection, balanced earth fault protection, and overcurrent protection. It describes how each protection scheme detects faults or unbalanced loading conditions in the alternator. Differential protection compares currents on each side of the alternator winding and trips if they are unequal due to an internal fault. Other schemes like negative phase sequence and earth fault protection are used to detect unbalanced or ground faults that may not be caught by differential protection.
1. Transformers have on-load and off-load tap changers that allow adjusting the transformer's output voltage without interrupting the load current. On-load tap changers can adjust voltage while energized using fast-acting switches, while off-load tap changers require de-energizing the transformer to change taps.
2. On-load tap changers are commonly used in power generation and distribution transformers to control voltage as load and line conditions vary. They monitor voltage and raise or lower taps using an automatic voltage regulator. Off-load tap changers are typically used in solar and wind projects where the generator voltage is low-voltage.
3. The on-load tap changer maintains uninterrupted
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,
This document discusses optimal power flow (OPF) analysis, which determines optimal settings for control variables like generator outputs and transformer taps to minimize objectives like power losses while satisfying operating constraints. The key aspects covered include: the differences between standard load flow and OPF; examples of optimization problems; common objective functions and control variables used in OPF; and the use of an OPF study case editor to set up optimization problems.
This document discusses special electrical machines, specifically permanent magnet synchronous motors (PMSM). It describes PMSM as a brushless DC motor with permanent magnets on the rotor that create magnetic poles instead of a field winding. The document outlines the basic construction and working principle of PMSM, noting that a rotating magnetic field from the stator interacts with the permanent rotor magnets to produce torque. Applications mentioned include servo drives, robotics, traction systems, and railway transportation.
Three Phase Transformer
Presented by:
Rizwan Yaseen 2017-EE-432
Zeeshan Saeed 2017-EE-414
Muhammad Hamad 2017-EE-404
Muhammad Zeeshan 2017-EE-402
A three phase transformer is made of three sets of primary and secondary windings wound around the legs of a common iron core. It allows for higher transmission voltages using lower amperage wiring. The core can be constructed as either a core type or shell type configuration. A three phase transformer works by inducing secondary voltages from the three phase primary voltages to maintain the proper phase relationships for power distribution.
A transformer is a device that changes alternating current (ac) electric power at one voltage level to ac electric power at another voltage level through the action of a magnetic field. An ideal transformer is a lossless device that transfers power efficiently between its two windings. A real transformer is modeled using an equivalent circuit that accounts for power losses, including copper losses, eddy current losses, hysteresis losses, and leakage fluxes. The parameters of the equivalent circuit can be determined experimentally using open-circuit and short-circuit tests.
This document provides a 24 step process for designing a 250 VA, 250 Watt isolation transformer with specifications including 230 V input and output voltages, 95% efficiency, and 1.6 T flux density. Key details include:
1) Total power is calculated to be 513.16 Watts accounting for losses.
2) Core geometry is calculated to be 18.04 cm^5 and the closest lamination is EI-150.
3) Primary and secondary winding properties like number of turns and copper losses are calculated based on the specifications.
4) Total copper loss is calculated to be 8.747 Watts and voltage regulation is 3.5%, meeting the specified 5% maximum.
The document discusses different types of conductors used in power transmission. It describes the major materials used which include copper, aluminum, and aluminum alloys. The major types of conductors are identified as AAC (All Aluminum Conductor), AAAC (All Aluminum Alloy Conductor), ACSR (Aluminum Conductor Steel Reinforced), and ACAR (Aluminum Conductor Aluminum Alloy Reinforced). Key factors to consider in conductor selection include physical properties of the materials, mechanical characteristics, electrical performance, and cost. The design of conductors involves tradeoffs between these various factors.
This document summarizes the summer training report submitted by four students from Amritsar College of Engineering & Technology at the Punjab State Power Corporation Limited Transformer Repair Workshop in Amritsar. The workshop repairs damaged transformers to save costs compared to the private sector. It has two main circles and aims to repair 120 units per month. The report describes the workshop organization and sections for washing, repairing, drying, assembling, testing and storing transformers. It also explains transformer components, types, workings, efficiency tests and applications.
Overhead line insulators are used to electrically isolate power line conductors from each other and supporting structures. They protect transmission lines from over-voltages caused by lightning and switching. The most common insulator materials are porcelain and glass. Pin insulators are used for voltages up to 33kV, while suspension insulators are preferred for higher voltages as they can be scaled more easily. Proper insulator selection and arrangement is needed to achieve uniform voltage distribution across the insulator string. Sag in overhead lines must be properly calculated to limit conductor tension within safe levels while minimizing material usage and clearance heights.
The document discusses the working of transformers. It explains that a transformer is a static device that changes alternating current (AC) voltage levels through magnetic induction between two coils. The changing current in the primary coil produces a magnetic field that is concentrated in the secondary coil, inducing a voltage across it. Transformers consist of magnetic cores and windings, and can be classified by phase (single or three phase), core type (core or shell), or cooling system (self-cooled, oil-cooled, air-cooled). Transformers operate on the principle of mutual induction to increase or decrease voltages for applications.
Presentation about transformer and its types M Tahir Shaheen
- A transformer is a static device that changes electrical power at one voltage level into electrical power at another voltage level through magnetic induction. It does not change the frequency.
- There are two main types of transformers: step-up transformers, which increase voltage, and step-down transformers, which decrease voltage. This is achieved by varying the number of turns in the primary and secondary coils.
- Transformers work on the principle of mutual induction. A changing magnetic field induced by alternating current in the primary coil induces a voltage in the secondary coil.
A transformer is a static device that changes alternating current (AC) at one voltage level to AC at another voltage level through electromagnetic induction. It consists of two coils, the primary and secondary windings, wrapped around a laminated iron core. When an alternating current is applied to the primary winding, it produces an alternating magnetic field that induces a voltage in the secondary winding. This allows the transformer to step up or step down voltages without changing the frequency. The transformer transfers power between its two coils through electromagnetic coupling between the coils wound around the iron core.
The document discusses transformer heat run testing using the loading back method. It describes the loading back method as using two transformers connected in parallel, with one transformer under test and the other acting as a source. The source transformer is used to provide the iron and copper losses for the transformer under test by using variable sources for each. The requirements for the source transformer such as voltage and current capabilities are also outlined to properly test the transformer under test.
The document provides the syllabus for an 8-week basic electrical, electronics, and computer training module. It covers topics taught each week, including electrical safety, hand tools, circuits, electrical measuring instruments, single and 3-phase systems, motors, transformers, semiconductors, rectifiers, computers, MS Office applications, and networking basics. It also lists the skills trainees will gain in areas like electrical/electronic component connection, measurement, identification and testing.
The document discusses the working principle, design, applications, advantages, and limitations of a momentum transformer. It introduces momentum transformers and how they transfer electrical energy from one circuit to another using electromagnetism and electromagnetic induction. Some applications mentioned include auto-starters for motors, balance coils in AC distribution systems, and as regulating or booster transformers. Advantages include continuously varying voltage, while disadvantages include cost, space required, and weight. Cautions discussed include using high quality magnetic core materials and not connecting the transformer to a direct source or leaving the secondary open-circuited.
The document summarizes a team's project to create a power meter that monitors energy usage through a graphical interface. It discusses the mechanical design, project management approach, resources used, code repository structure, code reviews, IP design, hardware-software interface, functional verification, cost estimate, lessons learned, roadblocks encountered, and conclusions. The team successfully interfaced their design with an evaluation board and displayed measured data on an LCD.
Digital transformer protection systemsmichaeljmack
The document discusses Beckwith's digital transformer protection systems. The systems provide:
1) Software that adapts to any transformer winding or CT configuration to provide differential protection for up to 4 windings.
2) A full complement of protective functions including metering, oscillography, and communication capabilities.
3) User-friendly software for configuring, monitoring, and analyzing the protection systems. The software facilitates commissioning and fault diagnosis.
The document discusses high voltage distribution systems (HVDS) as an alternative to traditional low voltage distribution systems (LVDS). It outlines three main types of HVDS - phase-neutral, phase-phase, and phase-ground - and describes their components and configurations. HVDS is presented as a technically superior option to LVDS, offering benefits like lower line losses, improved voltage profile, reduced theft and failures. Restructuring an existing LVDS network to HVDS could result in power loss reductions of 25-80% and payback periods of around 18 months, making it a viable option.
This document discusses different types of transformers. The most common type is a step-down transformer, which is widely used to convert mains voltage to low voltage for powering electronics. It has an insulated lamination core and is available in power ratings ranging from milliwatts to megawatts. Current transformers measure current flowing through their primary coil and provide a proportional current in the secondary coil. Voltage transformers, also called potential transformers, are used for metering and protection in high-voltage circuits, connecting in parallel. Pulse transformers transmit rectangular electrical pulses, optimized for that function. Radio frequency work uses transformers without steel laminations, unsuitable for those frequencies.
R-APDRP (Restructured Accelerated Power Development And Reforms Programme)AMIT YADAV
This document discusses the R-APDRP project which aims to reduce aggregate technical and commercial losses in the electricity distribution system from over 30% to less than 15% over 5 years. It does this through automation and integration of utility processes. Part A of the project, which can be handled by HCL, involves activities like consumer indexing, GIS mapping, metering infrastructure installation, and establishing a baseline data system. Major challenges of implementation include addressing ground realities, meeting timelines, and overcoming technical issues in systems like CCC and WSS. The document also provides background information on India's power scenario and the responsibilities of junior engineers.
It is a presentation about GIS in RAPDRP project. DISCOM can use GIS tools and data for their betterment to navigation towards their electrical assets & for calculation of AT&C losses.
Smart Grids:Enterprise GIS For Distribution Loss Reduction in Electric Utilit...HIMADRI BANERJI
1. The document discusses implementing an Enterprise GIS system for two power distribution companies in Delhi, BRPL and BYPL, to help reduce distribution losses and improve customer service.
2. Key goals of implementing GIS include reducing outage times, stopping power theft, improving asset management, and achieving a zero fatality safety rate.
3. The implementation plan includes developing GIS data models, capturing network and customer data digitally, integrating GIS with other systems like SAP and SCADA, and providing network analysis tools.
4. Estimates show the project has a payback period of less than 1 year and will generate over $400 million in additional revenue over 3 years with returns of 138%, making
Dissolved gas analysis (DGA) of transformer oil detects gases generated within oil-filled transformers that can indicate internal faults. Key gases include hydrogen, methane, ethylene and acetylene, which can identify thermal or electrical issues. DGA interpretation methods like the key gas method or IEC gas ratio method analyze individual and total dissolved combustible gas concentrations to evaluate transformer condition and risk of failure. Regular oil sampling per ASTM standards from the drain point helps assess the internal condition of transformers to support effective maintenance.
Capacitor bank and improvement of power factorAhshan Kabir
In these presentation ,we have discussed about power factor, disadvantages of low power factor and how to improve it. Also, capacitor bank and how to install capacitor bank are discussed.
The document summarizes the basics of a transformer. It discusses that a transformer transfers electrical energy from one circuit to another through inductively coupled coils. It consists of a core with two separate coils wound around it. The primary coil receives energy from an AC source which generates a magnetic field and induces a voltage in the secondary coil. The ratio of voltages depends on the turns ratio between the coils. Common transformer types include step-up, step-down, auto and poly-phase transformers. Transformers work on the principle of mutual induction and Faraday's law of induction.
• Solar resource assessment
• Determination of profitability of a PV plant
• Selection and optimization of the site.
• Selection of components (Inverters, Modules, Protection and Wiring, Grounding, Transformers, Metering, Grid Connection)
• Advanced calculations : Estimated losses; Shading study, etc
• Electrical diagrams
Advance Electrical Design & Engineering Institute (AEDEI) ISO 9001:2008 Certified Institute of Electrical Design & Engineering training programs for Dedicated to Electrical Engineers . AEDEI is latest venture for providing the quality education in the best possible facilities is a key aim of Skill developments for various verticals in Electrical Engineering design.
ELECTRICAL SYSTEM DESIGN COURSE : Our trained Electrical Design Engineers working in various filed of Electrical industries (Design & Engineering, develops and supervises the manufacture, installation, operation and maintenance of equipment, machines and systems for the generation, distribution, utilization and control of electric power More..
SOLAR POWER PLANT DESIGN & ENGINEERING COURSE : The most significant future of solar energy is that it clean energy does not harm environments
TECHNICAL TRANSFORMER DESIGN COURSE : Transformer Design tool assists design engineers in choosing the most appropriate core material and size for a number of turn ratio and housing
OPERATING PRINCIPLES OF TRANSFORMER AND CONSTRUCTION.pptMadavanR1
The document provides an overview of operating principles of distribution transformers. It discusses the basic components of a transformer including the core, windings and cooling system. It explains how transformers work to step down voltages for distribution to consumers and discusses transformer types, connections, cooling methods and maintenance.
This document is an internship report on transformers produced by Siemens Pakistan. It discusses transformer construction including the core, windings, and tap changers. It describes the manufacturing process and types of windings used for different transformer ratings. Finally, it outlines common transformer tests performed, including on-load tests, impedance tests, and lightning impulse tests.
132 KV Grid Station Intern ship training reportMuntazir Mehdi
1. The document summarizes Muntazir Mehdi's two-week internship training at the 132 KV Substation Kamalabad operated by IESCO in Pakistan.
2. It provides details about the substation's configuration, with two incoming 132 KV lines, and describes the various components used in substations including transformers, circuit breakers, isolators, bus bars, insulators, and protection relays.
3. The substation components are classified and their functions and characteristics are explained over the course of the 14-page report.
A transformer consists of a magnetic core and two electrical windings. Electricity from the primary winding induces electricity in the secondary winding through magnetic coupling. There are two main types of construction: core type and shell type. Core type transformers have concentric windings around the core limbs, while shell type have windings around a central limb with side limbs completing the magnetic path. Transformers change voltage and current levels, allow impedance matching, and provide electrical isolation between circuits. They are vital components for electric power transmission and distribution.
Transformer types core, shell, toroidal. steps to design a EI core type transformer by calculating tongue width, stack height etc and two examples are given
University college of engineering, rajasthan technical universityDivyansh Gupta
The document provides information about a presentation given at BHEL, Bhopal on vocational training. It discusses BHEL, its establishment and operations. BHEL was established in 1964 and owns power plant manufacturing facilities across India. The document then discusses BHEL's facility in Bhopal, which was established in 1964 and manufactures power plant equipment. It provides an overview of the types of equipment manufactured at BHEL Bhopal such as transformers, motors, switchgear, turbines and alternators.
This document is the seminar paper on transformers submitted by Pankaj Chaudhary, an electrical engineering student at Sanjay Gandhi Institute of Engineering & Technology, for his Bachelor of Technology degree. The paper discusses the basic construction, principles, types, cooling systems and applications of transformers. It explains how transformers work by transferring electrical energy from one circuit to another through magnetic induction without changing frequency, and how this principle allows efficient long-distance power transmission.
A transformer transfers electrical energy between two or more circuits through electromagnetic induction. It works by exploiting electromagnetic induction to produce an electromotive force in a conductor exposed to a time-varying magnetic field. Transformers are commonly used to increase or decrease alternating voltages in electric power applications. An ideal transformer model is often used to simplify analysis by assuming it is lossless and perfectly coupled with no energy losses. Real transformers have various losses, like core losses from hysteresis and eddy currents, that the ideal model neglects.
The document discusses the history and development of transformers over the past 130 years. It describes how transformers enabled the breakthrough of efficient long-distance AC power transmission systems. While the basic principle of a transformer remains unchanged, the technology has advanced tremendously, allowing for higher voltages, efficiencies, and power capacities. ABB is now the world's largest manufacturer of transformers, supplying products for power grids, buildings, industries, and transportation worldwide.
A transformer transfers electrical energy from one circuit to another through electromagnetic induction. It converts an alternating current from one voltage to another without changing frequency. An ideal transformer is 100% efficient, but real transformers have some losses due to winding resistance, leakage flux, hysteresis, and eddy currents. Transformers come in different types for various applications and use laminated cores to reduce eddy current losses.
1. A transformer transfers electrical energy from one circuit to another through electromagnetic induction without changing frequency.
2. Transformers have two windings, the primary and secondary, wound around a magnetic core. This allows a changing magnetic field in the primary to induce voltage in the secondary.
3. Transformers come in different types for various applications, including step-up transformers which increase voltage and step-down transformers which decrease voltage from a main supply. Larger power transformers are used to transmit electricity over long distances.
Distribution transformers are used to reduce high primary voltages to lower utilization voltages for consumers. They come in various types including pole mounted, pad mounted, and underground transformers. Losses in distribution transformers include core losses from hysteresis and eddy currents, as well as copper losses from winding resistance. Efficiency is calculated based on total energy delivered over 24 hours rather than power ratio at full load, since distribution transformers rarely operate at full load. A breather uses silica gel to absorb moisture from transformer air and maintain a low dew point.
This document provides information about transformers, including:
1) Transformers work by mutual inductance between two coils linked by a magnetic flux, allowing conversion of voltages while keeping frequency the same.
2) Transformers consist of two inductive windings and a laminated steel core to reduce losses. They are classified based on factors like phase, core type, cooling method, and application.
3) Transformers experience losses from hysteresis in the core, eddy currents, and resistive heating of windings. Proper design aims to minimize different types of losses depending on the transformer's role.
This document discusses the construction and working of transformers. It begins with an introduction that defines a transformer as a device that changes AC electric power at one voltage level to another through magnetic coupling of two coils. It then covers the main topics of the structure and working principle of transformers, the different types of constructions including core and shell types, losses in transformers including copper, hysteresis and eddy current losses, the differences between ideal and practical transformers, and applications such as in transmission and distribution of power.
Three phase transformers are used to efficiently transmit power in three phase power systems. They have three coils on a single magnetic core that allow power to be transmitted at higher voltages to reduce transmission losses. Three phase transformers can be constructed as either core type, with a single core and coils, or shell type, with separate cores for each phase. They are commonly used in power generation, transmission and industrial applications to transform voltages for distribution or motor loads.
This document provides an overview of transformers, including their structure, working principle, construction, losses, and applications. Transformers are devices that change AC electric power at one voltage level to another through magnetic coupling of two coils. They allow interchange of electric energy between circuits without a direct connection. The transformer consists of a primary coil, secondary coil, and magnetic core. When an alternating current flows through the primary, it induces a changing magnetic flux that is transferred to the secondary coil to induce voltage. Transformers experience losses from copper, hysteresis, and eddy currents. They are used widely in power transmission and applications like televisions and cameras.
The document provides information about the components and functions of a substation, including transformers, circuit breakers, and relays. It describes three types of circuit breakers used in the Sealdah Power House substation: air circuit breakers, which use high-pressure air to extinguish arcs; vacuum circuit breakers, which take advantage of arc non-sustainability in a vacuum; and oil circuit breakers, which use insulating oil to generate hydrogen gas to extinguish arcs. Specifications are provided for samples of equipment from the Sealdah Power House, including transformers, air circuit breakers, and vacuum circuit breakers.
A transformer is a static device that transfers electrical energy between two circuits through electromagnetic induction. It consists of two or more coils wound around an iron core. The coil connected to the power source is the primary winding, and the coil that provides power to the load is the secondary winding. Transformers are used to change the voltage levels in electrical systems. They are categorized as power transformers or electronic transformers based on their power ratings and applications. Power transformers are used in power generation, transmission and distribution systems to increase or decrease voltage levels, while electronic transformers operate at lower voltages and power levels in devices like computers and TVs.
Similar to Transformer, Electromagnetic WavesTheory (20)
Introduction- e - waste – definition - sources of e-waste– hazardous substances in e-waste - effects of e-waste on environment and human health- need for e-waste management– e-waste handling rules - waste minimization techniques for managing e-waste – recycling of e-waste - disposal treatment methods of e- waste – mechanism of extraction of precious metal from leaching solution-global Scenario of E-waste – E-waste in India- case studies.
Comparative analysis between traditional aquaponics and reconstructed aquapon...bijceesjournal
The aquaponic system of planting is a method that does not require soil usage. It is a method that only needs water, fish, lava rocks (a substitute for soil), and plants. Aquaponic systems are sustainable and environmentally friendly. Its use not only helps to plant in small spaces but also helps reduce artificial chemical use and minimizes excess water use, as aquaponics consumes 90% less water than soil-based gardening. The study applied a descriptive and experimental design to assess and compare conventional and reconstructed aquaponic methods for reproducing tomatoes. The researchers created an observation checklist to determine the significant factors of the study. The study aims to determine the significant difference between traditional aquaponics and reconstructed aquaponics systems propagating tomatoes in terms of height, weight, girth, and number of fruits. The reconstructed aquaponics system’s higher growth yield results in a much more nourished crop than the traditional aquaponics system. It is superior in its number of fruits, height, weight, and girth measurement. Moreover, the reconstructed aquaponics system is proven to eliminate all the hindrances present in the traditional aquaponics system, which are overcrowding of fish, algae growth, pest problems, contaminated water, and dead fish.
A review on techniques and modelling methodologies used for checking electrom...nooriasukmaningtyas
The proper function of the integrated circuit (IC) in an inhibiting electromagnetic environment has always been a serious concern throughout the decades of revolution in the world of electronics, from disjunct devices to today’s integrated circuit technology, where billions of transistors are combined on a single chip. The automotive industry and smart vehicles in particular, are confronting design issues such as being prone to electromagnetic interference (EMI). Electronic control devices calculate incorrect outputs because of EMI and sensors give misleading values which can prove fatal in case of automotives. In this paper, the authors have non exhaustively tried to review research work concerned with the investigation of EMI in ICs and prediction of this EMI using various modelling methodologies and measurement setups.
Using recycled concrete aggregates (RCA) for pavements is crucial to achieving sustainability. Implementing RCA for new pavement can minimize carbon footprint, conserve natural resources, reduce harmful emissions, and lower life cycle costs. Compared to natural aggregate (NA), RCA pavement has fewer comprehensive studies and sustainability assessments.
Presentation of IEEE Slovenia CIS (Computational Intelligence Society) Chapte...University of Maribor
Slides from talk presenting:
Aleš Zamuda: Presentation of IEEE Slovenia CIS (Computational Intelligence Society) Chapter and Networking.
Presentation at IcETRAN 2024 session:
"Inter-Society Networking Panel GRSS/MTT-S/CIS
Panel Session: Promoting Connection and Cooperation"
IEEE Slovenia GRSS
IEEE Serbia and Montenegro MTT-S
IEEE Slovenia CIS
11TH INTERNATIONAL CONFERENCE ON ELECTRICAL, ELECTRONIC AND COMPUTING ENGINEERING
3-6 June 2024, Niš, Serbia
Optimizing Gradle Builds - Gradle DPE Tour Berlin 2024Sinan KOZAK
Sinan from the Delivery Hero mobile infrastructure engineering team shares a deep dive into performance acceleration with Gradle build cache optimizations. Sinan shares their journey into solving complex build-cache problems that affect Gradle builds. By understanding the challenges and solutions found in our journey, we aim to demonstrate the possibilities for faster builds. The case study reveals how overlapping outputs and cache misconfigurations led to significant increases in build times, especially as the project scaled up with numerous modules using Paparazzi tests. The journey from diagnosing to defeating cache issues offers invaluable lessons on maintaining cache integrity without sacrificing functionality.
Batteries -Introduction – Types of Batteries – discharging and charging of battery - characteristics of battery –battery rating- various tests on battery- – Primary battery: silver button cell- Secondary battery :Ni-Cd battery-modern battery: lithium ion battery-maintenance of batteries-choices of batteries for electric vehicle applications.
Fuel Cells: Introduction- importance and classification of fuel cells - description, principle, components, applications of fuel cells: H2-O2 fuel cell, alkaline fuel cell, molten carbonate fuel cell and direct methanol fuel cells.
1. By Mohammed AboAjmaa SDU
T.C
SÜLEMAN DEMİREL UNIVERSITY
FEN BİLİMLERİ ENSTİTÜSÜ
Mühendislik fakültesi
ELEKTRONİK VE HABERLEŞME
MÜHENDİSLİĞİ
Electromagnetic Waves Theory
A COURSE OFFERED BY
Prof. Dr. Mustafa MERDAN
RANSFORMERTREPORT ABOUT
Submitted by
MSc. Student
Mohammed Mahdi AboAjamm
Student No. 1330145006
2. By Mohammed AboAjmaa SDU
TRANSFORMER
What is Transformer?
A transformer is a static device that transfers electrical energy from
one circuit to another by electromagnetic induction without the
change in frequency. The transformer, which can link circuits with
different voltages, has been instrumental in enabling universal use
of the alternating current system for transmission and distribution
of electrical energy. Various components of power system, viz.
generators, transmission lines, distribution networks and finally the
loads, can be operated at their most suited voltage levels. As the
transmission voltages are increased to higher levels in some part
of the power system, transformers again play a key role in
interconnection of systems at different voltage levels.
Transformers occupy prominent positions in the power system,
being the vital links between generating stations and points of
utilization.
3. By Mohammed AboAjmaa SDU
The transformer is an electromagnetic conversion device in which
electrical energy received by primary winding is first converted into
magnetic energy which is reconverted back into a useful electrical
energy in other circuits (secondary winding, tertiary winding, etc.).
Thus, the primary and secondary windings are not connected
electrically, but coupled magnetically. A transformer is termed as
either a step-up or step-down transformer depending upon
whether the secondary voltage is higher or lower than the primary
voltage, respectively. Transformers can be used to either step-up
or step-down voltage depending upon the need and application;
hence their windings are referred as high-voltage/low-voltage or
high-tension/low-tension windings in place of primary/secondary
windings. links between generating stations and points of
utilization.
4. By Mohammed AboAjmaa SDU
Magnetic circuit:
Electrical energy transfer between two circuits takes place through
a transformer without the use of moving parts; the transformer
therefore has higher efficiency and low maintenance cost as
compared to rotating electrical machines. There are continuous
developments and introductions of better grades of core material.
The important stages of core material development can be
summarized as: non-oriented silicon steel, hot rolled grain oriented
silicon steel, cold rolled grain oriented (CRGO) silicon steel, Hi-B,
laser scribed and mechanically scribed. The last three materials
are improved versions of CRGO. Saturation flux density has
remained more or less constant around 2.0 Tesla for CRGO; but
there is a continuous improvement in watts/kg and volt-amperes/kg
characteristics in the rolling direction. The core material
developments are spearheaded by big steel manufacturers, and
the transformer designers can optimize the performance of core by
using efficient design and manufacturing technologies.
The core building technology has improved from the non-mitred to
mitred and then to the step-lap construction. A trend of reduction of
transformer core losses in the last few years is the result of a
considerable increase in energy costs. The better grades of core
steel not only reduce the core loss but they also help in reducing
the noise level by few decibels. Use of amorphous steel for
transformer cores results in substantial core loss reduction (loss is
about one-third that of CRGO silicon steel). Since the
manufacturing technology of handling this brittle material is
difficult, its use in transformers is not widespread.
5. By Mohammed AboAjmaa SDU
Windings:
The rectangular paper-covered copper conductor is the most
commonly used conductor for the windings of medium and large
power transformers. These conductors can be individual strip
conductors, bunched conductors or continuously transposed cable
(CTC) conductors.
In low voltage side of a distribution transformer, where much
fewer turns are involved, the use of copper or aluminum foils may
find preference. To enhance the short circuit withstand capability,
the work hardened copper is commonly used instead of soft
annealed copper, particularly for higher rating transformers. In the
case of a generator transformer having high current rating, the
CTC conductor is mostly used which gives better space factor and
reduced eddy losses in windings. When the CTC conductor is
used in transformers, it is usually of epoxy bonded type to enhance
its short circuit strength. Another variety of copper conductor or
aluminum conductor is with the thermally upgraded insulating
paper, which is suitable for hot-spot temperature of about 110°C. It
is possible to meet the special overloading conditions with the help
of this insulating paper. Moreover, the aging of winding insulation
material will be slowed down comparatively.
For better mechanical properties, the epoxy diamond dot paper
can be used as an interlayer insulation for a multi-layer winding.
High temperature superconductors may find their application in
power transformers which are expected to be available
commercially within next few years. Their success shall depend on
economic viability, ease of manufacture and reliability
considerations.
6. By Mohammed AboAjmaa SDU
Insulation and cooling:
Pre-compressed pressboard is used in windings as opposed to the
softer materials used in earlier days. The major insulation
(between windings, between winding and yoke, etc.) consists of a
number of oil ducts formed by suitably spaced insulating
cylinders/barriers. Well profiled angle rings, angle caps and other
special insulation components are also used. Mineral oil has
traditionally been the most commonly used electrical insulating
medium and coolant in transformers. Studies have proved that oil-
barrier insulation system can be used at the rated voltages greater
than 1000 kV. A high dielectric strength of oil-impregnated paper
and pressboard is the main reason for using oil as the most
important constituent of the transformer insulation system.
Manufacturers have used silicon-based liquid for insulation and
cooling. Due to non-toxic dielectric and self-extinguishing
properties, it is selected as a replacement of Askarel. High cost of
silicon is an inhibiting factor for its widespread use. Super-
biodegradable vegetable seed based oils are also available for use
in environmentally sensitive locations.
There is considerable advancement in the technology of gas
immersed transformers in recent years. SF6 gas has excellent
dielectric strength and is nonflammable. Hence, SF6 transformers
find their application in the areas where firehazard prevention is of
paramount importance. Due to lower specific gravity of SF6 gas,
the gas insulated transformer is usually lighter than the oil
insulated transformer. The dielectric strength of SF6 gas is a
function of the operating pressure; the higher the pressure, the
higher the dielectric strength. However, the heat capacity and
thermal time constant of SF6 gas are smaller than that of oil,
resulting in reduced overload capacity of SF6 transformers as
compared to oilimmersed transformers. Environmental concerns,
sealing problems, lower cooling capability and present high cost of
manufacture are the challenges which have to be overcome for the
widespread use of SF6 cooled transformers.
7. By Mohammed AboAjmaa SDU
PRINCIPLES For Transformer:
It is very common, for simplification or approximation purposes, to
analyze the transformer as an ideal transformer model as
represented in the two images. An ideal transformer is a
theoretical, linear transformer that is lossless and
perfectly coupled; that is, there are no energy losses and flux is
completely confined within the magnetic core. Perfect coupling
implies infinitely high core magnetic permeability and winding
inductances and zero net magneto motive force. varying current in
the transformer's primary winding creates a varying magnetic flux
in the core and a varying magnetic field impinging on the
secondary winding. This varying magnetic field at the secondary
induces a varying electromotive force(EMF) or voltage in the
secondary winding. The primary and secondary windings are
wrapped around a core of infinitely high magnetic permeability[d]
so that all of the magnetic flux passes through both the primary
and secondary windings with a voltage connected to theprimary
winding and load impedance connected to the secondary winding
the transformer currents flow in the indicated directions. (See also
Polarity.)
According to Faraday's law of induction, since the same magnetic
flux passes through both the primary and secondary windings in an
ideal transformer, a voltage is induced in each winding]
, according
to eq. (1)
8. By Mohammed AboAjmaa SDU
In the secondary winding case, according to eq. (2) in the primary
winding case.
9. By Mohammed AboAjmaa SDU
The primary EMF is sometimes termed counter EMFThis is in
accordance with Lenz's law, which states that induction of EMF
always opposes development of any such change in magnetic
field. The transformer winding voltage ratio is thus shown to be
directly proportional to the winding turns ratio according to eq. (3).
According to the law of Conservation of Energy(In physics, the law
of conservation of energy states that the total energy of an isolated
system cannot change—it is said to be conserved over time.
Energy can be neither created nor destroyed, but can change
form, for instance chemical energy can be converted to kinetic
energy in the explosion of a stick of dynamite. A consequence of
the law of conservation of energy is that a perpetual motion
machine of the first kind cannot exist. That is to say, no system
without an external energy supply can deliver an unlimited amount
of energy to its surroundings.) any load impedance connected to
the ideal transformer's secondary winding results in conservation
of apparent, real and reactive power consistent with eq. (4).
10. By Mohammed AboAjmaa SDU
The ideal transformer identity shown in eq. (5) is a reasonable
approximation for the typical commercial transformer, with voltage
ratio and winding turns ratio both being inversely proportional to
the corresponding current ratio.
By Ohm's Law and the ideal transformer identity: the secondary
circuit load impedance can be expressed as eq. (6)
The apparent load impedance referred to the primary circuit is
derived in eq. (7) to be equal to the turns ratio squared times the
secondary circuit load impedance.
12. By Mohammed AboAjmaa SDU
MAGNETIC CORE:
A magnetic core is a piece of magnetic material with a high
permeability(permeability is the measure of the ability of a material
to support the formation of a magnetic field within itself. In other
words, it is the degree of magnetization that a material obtains in
response to an applied magnetic field. Magnetic permeability is
typically represented by the Greek letter μ. The term was coined in
September 1885 by Oliver Heaviside. The reciprocal of magnetic
permeability is magnetic reluctivity.In SI units, permeability is
measured in henries per meter (H·m−1
), or newtons per ampere
squared (N·A−2
). The permeability constant (μ0), also known as the
magnetic constant or the permeability of free space, is a measure
of the amount of resistance encountered when forming a magnetic
field in a classical vacuum. The magnetic constant has the exact
(defined) value µ0 = 4π×10−7
H·m−1
≈ 1.2566370614…×10−6
H·m−1
or N·A−2
).) used to confine and guide magnetic fields in electrical,
electromechanical and magnetic devices such as electromagnets,
transformers, electric motors, generators, inductors, magnetic
recording heads, and magnetic assemblies. It is made of
ferromagnetic metal such as iron, or ferromagnetic compounds
such as ferrites. The high permeability, relative to the surrounding
air, causes the magnetic field lines to be concentrated in the core
material. The magnetic field is often created by a coil of wire
around the core that carries a current. The presence of the core
can increase the magnetic field of a coil by a factor of several
thousand over what it would be without the core.
The use of a magnetic core can enormously concentrate the
strength and increase the effect of magnetic fields produced by
electric currents and permanent magnets.
13. By Mohammed AboAjmaa SDU
The properties of a device will depend crucially on the following
factors:
the geometry of the magnetic core.
the amount of air gap in the magnetic circuit.
the properties of the core material (especially permeability
and hysteresis).
the operating temperature of the core.
whether the core is laminated to reduce eddy currents.
In many applications it is undesirable for the core to retain
magnetization when the applied field is removed. This property,
called hysteresis can cause energy losses in applications such as
transformers. Therefore 'soft' magnetic materials with low
hysteresis, such as silicon steel, rather than the 'hard' magnetic
materials used for permanent magnets, are usually used in cores.
:SOFT IRON
is used in magnetic assemblies, electromagnets and in some
electric motors; and it can create a concentrated field that is as
much as 50,000 times more intense than an air core. Iron is
desirable to make magnetic cores, as it can withstand high levels
of magnetic field without saturating (up to 2.16 teslas) It is also
used because, unlike "hard" iron, it does not remain magnetised
when the field is removed, which is often important in applications
where the magnetic field is required to be repeatedly
switched.Unfortunately, due to the electrical conductivity of the
metal, at AC frequencies a bulk block or rod of soft iron can often
suffer from large eddy currents circulating within it that waste
energy and cause undesirable heating of the iron.
14. By Mohammed AboAjmaa SDU
VITREOUS METAL:
Amorphous metal (also known metallic glass or glassy metal) is a
solid metallic material, usually an alloy, with a disordered atomic-
scale structure. Most metals are crystalline in their solid state,
which means they have a highly ordered arrangement of atoms.
Amorphous metals are non-crystalline, and have a glass-like
structure. But unlike common glasses, such as window-glass,
which are typically insulators, amorphous metals have good
electrical conductivity. There are several ways in which amorphous
metals can be produced, including extremely rapid cooling,
physical vapor deposition, solid-state reaction, ion irradiation, and
mechanical alloying.
More recently, batches of amorphous steel have been produced
that demonstrate strengths much greater than conventional steel
alloys is a variety of alloys that are non-crystalline or glassy. These
are being used to create high-efficiency transformers. The
materials can be highly responsive to magnetic fields for low
hysteresis losses, and they can also have lower conductivity to
reduce eddy current losses. China is currently making widespread
15. By Mohammed AboAjmaa SDU
industrial and power grid usage of these transformers for new
installations.Currently the most important application is due to the
special magnetic properties of some ferromagnetic metallic
glasses. The low magnetization loss is used in high efficiency
transformers (amorphous metal transformer) at line frequency and
some higher frequency transformers. Amorphous steel is a very
brittle material which makes it difficult to punch into motor
laminations. Also electronic article surveillance (such as theft
control passive ID tags,) often uses metallic glasses because of
these magnetic properties.
BEHAVIOR OF MAGNETIC MATERIALS:
In Eq. ( M=XmH), we describe the macroscopic magneticproperty
of a linear. isotropicmedium) defining the magnetic
susceptibilityXm.which is unit less. The magnetic susceptibilityand
the relative permeability are related as follows:
Magnetic material can be roughly classifiedinto three maim group
inaccordance with theμrvalues.
Diamagnetic, if μ r≤ 1 (Xm is a very small negative number).
Paramagnetic. if μ r≥ 1 (Xm is a very small positive number).
Ferromagnetic, if μr>> 1(Xm is a large positive number).
16. By Mohammed AboAjmaa SDU
DIAMAGNETISM:
Diamagnetic materials create an induced magnetic field in a
an externally applied magnetic field, and aredirection opposite to
repelled by the applied magnetic field. In contrast, the opposite
behavior is exhibited by paramagnetic materials. Diamagnetism is
a quantum mechanical effect that occurs in all materials; when it is
ontribution to the magnetism the material is called athe only c
diamagnet. Unlike a ferromagnet, a diamagnet is not a permanent
(the permeability0magnet. Its magnetic permeability is less than μ
of free space). In most materials diamagnetism is a weak effect,
superconductor repels the magnetic field entirely, apart frombut a
a thin layer at the surface.Diamagnetic materials, like water, or
water based materials, have a relative magnetic permeability that
bilityis less than or equal to 1, and therefore a magnetic suscepti
less than or equal to 0, since susceptibility is defined as
− 1.r= μmχ
17. By Mohammed AboAjmaa SDU
This means that diamagnetic materials are repelled by magnetic
fields. However, since diamagnetism is such a weak property its
effects are not observable in everyday life. For example, the
magnetic susceptibility of diamagnets such as water is χm =
−9.05×10−6
. The most strongly diamagnetic material is bismuth, χm
= −1.66×10−4
, although pyrolytic carbon may have a susceptibility
of χm = −4.00×10−4
in one plane. Nevertheless, these values are
orders of magnitude smaller than the magnetism exhibited by
paramagnets and ferromagnets. Note that because χm is derived
from the ratio of the internal magnetic field to the applied field, it is
a dimensionless value.
All conductors exhibit an effective diamagnetism when they
experience a changing magnetic field. The Lorentz force on
electrons causes them to circulate around forming eddy currents.
The eddy currents then produce an induced magnetic field
opposite the applied field, resisting the conductor's motion.
:PARAMAGNETISM
is a form of magnetism whereby certain materials are attracted by
an externally applied magnetic field, and form internal, induced
magnetic fields in the direction of the applied magnetic field. In
contrast with this behavior, diamagnetic materials are repelled by
magnetic fields and form induced magnetic fields in the direction
opposite to that of the applied magnetic field. Paramagnetic
materials include most chemical elements and some compounds;
they have a relative magnetic permeability greater than or equal to
1 ( μ r≥ 1 ) (i.e., a positive magnetic susceptibility) and hence are
attracted to magnetic fields. The magnetic moment induced by the
applied field is linear in the field strength and rather weak. It
typically requires a sensitive analytical balance to detect the effect
and modern measurements on paramagnetic materials are often
conducted with a SQUID magnetometer.
18. By Mohammed AboAjmaa SDU
Paramagnetic materials have a small, positive susceptibility to
magnetic fields. These materials are slightly attracted by a
magnetic field and the material does not retain the magnetic
properties when the external field is removed. Paramagnetic
properties are due to the presence of some unpaired electrons,
and from the realignment of the electron paths caused by the
external magnetic field. Paramagnetic materials include
magnesium, molybdenum, lithium, and tantalum.
Unlike ferromagnets, paramagnets do not retain any magnetization
in the absence of an externally applied magnetic field because
thermal motion randomizes the spin orientations. Some
paramagnetic materials retain spin disorder at absolute zero,
meaning they are paramagnetic in the ground state. Thus the total
magnetization drops to zero when the applied field is removed.
Even in the presence of the field there is only a small induced
magnetization because only a small fraction of the spins will be
oriented by the field. This fraction is proportional to the field
strength and this explains the linear dependency. The attraction
experienced by ferromagnetic materials is non-linear and much
stronger, so that it is easily observed, for instance, by the attraction
between a refrigerator magnet and the iron of the refrigerator itself.
19. By Mohammed AboAjmaa SDU
FERROMAGNETISM:
Is the basic mechanism by which certain materials (such as iron)
form permanent magnets, or are attracted to magnets. In physics,
several different types of magnetism are distinguished.
Ferromagnetism (including ferrimagnetism) is the strongest type: it
is the only one that typically creates forces strong enough to be
felt, and is responsible for the common phenomena of magnetism
encountered in everyday life. Substances respond weakly to
magnetic fields with three other types of magnetism,
paramagnetism, diamagnetism, and antiferromagnetism, but the
forces are usually so weak that they can only be detected by
sensitive instruments in a laboratory. An everyday example of
ferromagnetism is a refrigerator magnet used to hold notes on a
refrigerator door. The attraction between a magnet and
ferromagnetic material is "the quality of magnetism first apparent to
the ancient world, and to us today".
Permanent magnets (materials that can be magnetized by an
external magnetic field and remain magnetized after the external
field is removed) are either ferromagnetic or ferrimagnetic, as are
other materials that are noticeably attracted to them. Only a few
substances are ferromagnetic. The common ones are iron, nickel,
cobalt and most of their alloys, some compounds of rare earth
metals, and a few naturally-occurring minerals such as lodestone.
Ferromagnetism is very important in industry and modern
technology, and is the basis for many electrical and
electromechanical devices such as electromagnets, electric
motors, generators, transformers, and magnetic storage such as
tape recorders, and hard disks.
20. By Mohammed AboAjmaa SDU
:CARBONYL IRON
Powdered cores made of carbonyl iron, a highly pure iron, have
high stability of parameters across a wide range of temperatures
and magnetic flux levels, with excellent Q factors between 50 kHz
and 200 MHz. Carbonyl iron powders are basically constituted of
micrometer-size spheres of iron coated in a thin layer of electrical
insulation. This is equivalent to a microscopic laminated magnetic
circuit (see silicon steel, above), hence reducing the eddy currents,
particularly at very high frequencies. A popular application of
carbonyl iron-based magnetic cores is in high-frequency and
broadband inductors and transformers.
:IRON POWDER
Powdered cores made of hydrogen reduced iron have higher
permeability but lower Q. They are used mostly for
electromagnetic interference filters and low-frequency chokes,
mainly in switched-mode power supplies.
21. By Mohammed AboAjmaa SDU
EDDY CURRENTS AND WINDING STRAY LOSSES:
The load loss of a transformer consists of losses due to ohmic
resistance of windings (I2
R losses) and some additional losses.
These additional losses are generally known as stray losses,
which occur due to leakage field of windings and field of high
current carrying leads/bus-bars. The stray losses in the windings
are further classified as eddy loss and circulating current loss. The
other stray losses occur in structural steel parts. There is always
some amount of leakage field in all types of transformers, and in
large power transformers (limited in size due to transport and
space restrictions) the stray field strength increases with growing
rating much faster than in smaller transformers. The stray flux
impinging on conducting parts (winding conductors and structural
components) gives rise toeddy currents in them. The stray losses
in windings can be substantially high in large transformers if
conductor dimensions and transposition methods are not chosen
properly.
Today’s designer faces challenges like higher loss capitalization
and optimum performance requirements. In addition, there could
be constraints on dimensions and weight of the transformer which
is to be designed. If the designer lowers current density to reduce
the DC resistance copper loss (I2
R loss), the eddy loss in windings
increases due to increase in conductor dimensions. Hence, the
winding conductor is usually subdivided with a proper transposition
method to minimize the stray losses in windings.
In order to accurately estimate and control the stray losses in
windings and structural parts, in-depth understanding of the
fundamentals of eddy currents starting from basics of
electromagnetic fields is desirable. The fundamentals are
described in first few sections of this chapter.
22. By Mohammed AboAjmaa SDU
EDDY CURRENTS:
Eddy currents (also called Foucault currentsare circular
electric currents induced within conductors by a changing
magnetic field in the conductor, due to Faraday's law of
induction. Eddy currents flow in closed loops within
conductors, in planes perpendicular to the magnetic field.
They can be induced within nearby stationary conductors by
a time-varying magnetic field created by an AC electromagnet
or transformer, for example, or by relative motion between a
magnet and a nearby conductor. The magnitude of the current
in a given loop is proportional to the strength of the magnetic
field, the area of the loop, and the rate of change of flux, and
inversely proportional to the resistivity of the material.
By Lenz's law, an eddy current creates a magnetic field that
opposes the magnetic field that created it, and thus eddy
currents react back on the source of the magnetic field. For
example, a nearby conductive surface will exert a drag force
on a moving magnet that opposes its motion, due to eddy
currents induced in the surface by the moving magnetic field.
This effect is employed in eddy current brakes which are used
to stop rotating power tools quickly when they are turned off.
The current flowing through the resistance of the conductor
also dissipates energy as heat in the material. Thus eddy
currents are a source of energy loss in alternating current
(AC) inductors, transformers, electric motors and generators,
and other AC machinery, requiring special construction such
as laminated magnetic cores to minimize them. Eddy currents
are also used to heat objects in induction heating furnaces
and equipment, and to detect cracks and flaws in metal parts
using eddy-current testing instruments. Under certain
assumptions (uniform material, uniform magnetic field, no
skin effect, etc.) the power lost due to eddy currents per unit
mass for a thin sheet or wire can be calculated from the
following equation:
23. By Mohammed AboAjmaa SDU
where
P is the power lost per unit mass (W/kg),
Bp is the peak magnetic field (T),
d is the thickness of the sheet or diameter of the wire (m),
f is the frequency (Hz),
k is a constant equal to 1 for a thin sheet and 2 for a thin wire,
ρ is the resistivity of the material (Ω m), and
D is the density of the material (kg/m3).
This equation is valid only under the so-called quasi-static
conditions, where the frequency of magnetisation does not result in
the skin effect; that is, the electromagnetic wave fully penetrates
the material.
:SKIN EFFECT
In very fast-changing fields, the magnetic field does not penetrate
completely into the interior of the material. This skin effect renders
the above equation invalid. However, in any case increased
frequency of the same value of field will always increase eddy
currents, even with non-uniform field penetration
The penetration depth for a good conductor can be calculated from
the following equation:
24. By Mohammed AboAjmaa SDU
HEAT TRANSFER EFFECTS:
A load serving transformer not only experiences an electrical
process but also goes through a thermal process that is driven by
heat. The heat generated by the no-load and load losses is the
main source of temperature rise in the transformer. However, the
losses of the windings and stray losses seen from the structural
parts are the main factors of heat generation within the
transformer. The thermal energy produced by the windings is
transferred to the winding insulation and consequently to the oil
and transformer walls. This process will continue until an
equilibrium state is reached when the heat generated by the
windings equals the heat taken away by some form of coolant or
cooling system . This heat transfer mechanism must not allow the
core, windings, or any structural parts to reach critical
temperatures that could possibly deteriorate the credibility of the
winding insulation. The dielectric insulating properties of the
insulation can be weakened if temperatures above the limiting
values are permitted . As a result, the insulation ages more rapidly,
reducing its normal life. Due to the temperature requirements of
the insulation, transformers utilize cooling systems to control the
temperature rise. The best method of absorbing heat from the
windings, core, and structural parts in larger power transformers is
to use oil .For smaller oil-field transformers, the tank surface is
used to dissipate heat to the atmosphere. For larger transformers,
heat exchangers, such as radiators, usually mounted beside the
tank, are employed to cool the oil. The standard identifies the type
of cooling system according to Table 1.
25. By Mohammed AboAjmaa SDU
THE MAGNETIC CIRCUIT:
The magnetic core has been introduced, an understanding of the
magnetic circuit is necessary to quantify the relationships between
voltage, current, flux, and field density.
26. By Mohammed AboAjmaa SDU
References….
1. Measurement and characterization of magnetic
materials, F. Fiorillo, Elsevier Academic Press,
2004
2. http://en.wikipedia.org/wiki/Transformer.
3. Elements of Electromagnetics by Matthew N.O.
Sadiku.
4. Fundamentals ofEngineering Electromagnetics,
Cheng. David K. Copyright 1993 by Addison-
Weceley Publishing Company, In c.
5. Transformer Engineering Design and Practice,
S.V.Kulkarni., S.A.Khaparde., Indian Institute of
Technology, Bombay,Mumbai, India., MARCEL
DEKKER, INC.