A bushing must be designed to withstand the electrical field strength produced in the insulation, when any earthed material is present
In a Oil-filled power transformers, their bushings, tap changer, insulation system and auxiliary equipment are critical to the operation of every electrical power system to such an extend that their reliable and uninterrupted functioning is a key factor in profitable generation, transmission and distribution.
Recent years on-line monitoring systems have been installed in a large scale at power transformers.
Practical handbook-for-relay-protection-engineersSARAVANAN A
The ‘Hand Book’ covers the Code of Practice in Protection Circuitry including standard lead and device numbers, mode of connections at terminal strips, colour codes in multicore cables, Dos and Donts in execution. Also, principles of various protective relays and schemes including special protection schemes like differential,
restricted, directional and distance relays are explained with sketches. The norms of protection of generators, transformers, lines & Capacitor Banks are also given.
A contactor is an electrically controlled switch used for switching electrical power circuits similar to a relay but with higher current ratings. It has three main components - contacts that carry the current, an electromagnet or coil that provides the driving force to close the contacts, and an insulating enclosure housing the contacts and coil. Contactors are designed to directly connect to high-current load devices above 15 amps, unlike relays which are lower capacity and can be normally open or closed. Modern contactors use techniques like vacuum or inert gases to extinguish arcs that occur when contacts open or close and can damage the contacts over time if not properly protected.
Online DGA Monitoring of Power Transformers Vaisala Group
In this webinar, we will review some of the fundamentals of dissolved gas analysis for power transformers. In addition to the topics below, we will also share data from field tests of Vaisala online monitors.
The document describes how to conduct short circuit and open circuit tests on transformers using a DPATT-3Bi device to measure copper and iron losses, respectively. It provides details on the test setups, calculations for full load current and no load current, and how to interpret the results displayed on the DPATT-3Bi screen. The document also lists standard limits for transformer impedance voltages and losses according to Indian standards.
Seminar for eight semester electrical engineering on Conventional and
Un-Conventional Partial Discharge Detection Methods in High Voltage XLPE Cable Accessories
A circuit breaker is a device that breaks an electrical circuit automatically or manually under normal, full, or short circuit conditions. When a fault occurs, the trip coil is energized and separates the contacts, extinguishing the arc through various methods. Common types of circuit breakers include oil, air blast, SF6, and vacuum. Oil circuit breakers use oil as an insulating medium but have disadvantages like fire risk. Vacuum circuit breakers use vacuum as the insulating medium and have the highest insulation strength. SF6 circuit breakers use sulfur hexafluoride gas which effectively absorbs electrons to extinguish arcs and are commonly used for high power and voltage applications.
This document provides information on a Power System Protection course taught at Vivekanandha College of Engineering for Women. The syllabus covers 5 units: introduction to protection schemes, relay operating principles and characteristics, apparatus protection, theory of circuit interruption, and circuit breakers. It lists textbooks and presents details on each unit, including topics like relay types, transformer/generator/motor protection, arc phenomena, and different circuit breaker types. The last section provides references for textbooks, websites, and presentations on related topics.
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
Practical handbook-for-relay-protection-engineersSARAVANAN A
The ‘Hand Book’ covers the Code of Practice in Protection Circuitry including standard lead and device numbers, mode of connections at terminal strips, colour codes in multicore cables, Dos and Donts in execution. Also, principles of various protective relays and schemes including special protection schemes like differential,
restricted, directional and distance relays are explained with sketches. The norms of protection of generators, transformers, lines & Capacitor Banks are also given.
A contactor is an electrically controlled switch used for switching electrical power circuits similar to a relay but with higher current ratings. It has three main components - contacts that carry the current, an electromagnet or coil that provides the driving force to close the contacts, and an insulating enclosure housing the contacts and coil. Contactors are designed to directly connect to high-current load devices above 15 amps, unlike relays which are lower capacity and can be normally open or closed. Modern contactors use techniques like vacuum or inert gases to extinguish arcs that occur when contacts open or close and can damage the contacts over time if not properly protected.
Online DGA Monitoring of Power Transformers Vaisala Group
In this webinar, we will review some of the fundamentals of dissolved gas analysis for power transformers. In addition to the topics below, we will also share data from field tests of Vaisala online monitors.
The document describes how to conduct short circuit and open circuit tests on transformers using a DPATT-3Bi device to measure copper and iron losses, respectively. It provides details on the test setups, calculations for full load current and no load current, and how to interpret the results displayed on the DPATT-3Bi screen. The document also lists standard limits for transformer impedance voltages and losses according to Indian standards.
Seminar for eight semester electrical engineering on Conventional and
Un-Conventional Partial Discharge Detection Methods in High Voltage XLPE Cable Accessories
A circuit breaker is a device that breaks an electrical circuit automatically or manually under normal, full, or short circuit conditions. When a fault occurs, the trip coil is energized and separates the contacts, extinguishing the arc through various methods. Common types of circuit breakers include oil, air blast, SF6, and vacuum. Oil circuit breakers use oil as an insulating medium but have disadvantages like fire risk. Vacuum circuit breakers use vacuum as the insulating medium and have the highest insulation strength. SF6 circuit breakers use sulfur hexafluoride gas which effectively absorbs electrons to extinguish arcs and are commonly used for high power and voltage applications.
This document provides information on a Power System Protection course taught at Vivekanandha College of Engineering for Women. The syllabus covers 5 units: introduction to protection schemes, relay operating principles and characteristics, apparatus protection, theory of circuit interruption, and circuit breakers. It lists textbooks and presents details on each unit, including topics like relay types, transformer/generator/motor protection, arc phenomena, and different circuit breaker types. The last section provides references for textbooks, websites, and presentations on related topics.
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
This document discusses maintenance schedules and strategies for electrical substation equipment like power transformers and distribution transformers. It provides daily, monthly, quarterly, half-yearly, and annual maintenance tasks for checking equipment operation and performance. Key tasks include checking oil levels, insulation resistance, dissolved gases in oil, and cleaning/replacing oil filters. The document also summarizes common equipment defects like leaks, loose connections, and winding issues; and stresses on equipment from electrical, thermal, mechanical, and environmental factors that cause deterioration over time.
This document describes various protection schemes for transformers, including differential, restricted earth fault, overcurrent, and thermal protection.
1) Differential protection compares currents entering and leaving the transformer zone to detect internal faults. It provides the best protection for internal faults.
2) Restricted earth fault protection is used to detect high-resistance winding-to-core faults not detectable by differential relays. It uses a neutral current transformer and is sensitive to internal earth faults.
3) Overcurrent protection uses relays with current coils to detect overloads and faults above a pickup threshold. It also includes ground-fault protection.
High Voltage On-Site Testing with Partial Discharge Measurement (Cigre 502)AHMED MOHAMED HEGAB
During the life cycle of high voltage (HV) apparatus or systems many tests and measurements are performed to characterize the insulation condition. The results of these tests and
measurements should be compiled in a “life data record”, which supplies information on trends of diagnostic indicator values. The HV on-site test with partial discharge (PD) measurement has an intermediate position between routine tests and in-service monitoring measurements (on-line or offline)
Testing and Condition Monitoring of Substation EquipmentsSumeet Ratnawat
Testing and condition monitoring of substation equipments,Transformer specifications,Monitoring of Transformer,On-load Tap changer,Overhauling,Tan delta and capacitance,Thermal imaging,Sweep frequency response analysis,Oil analysis of Switchgear elements containing oil,tests on insulating oil,Breaker monitoring,Condition monitoring of CT,Condition monitoring of CVT,Surge Arresters,Condition monitoring of relays.
This Presentation is about l.v switch gear design, presented during the graduation project final discussion 15/7/2018.
It presented a good summary of switch gear components and types and practicing on AL.HAMOOL W.T.P M.D.B design using SIEMENS SIVACON S8
This document provides an overview of power transformers, including:
1. It describes different types of transformers such as power, distribution, auto, step-up, step-down transformers and discusses their various components and specifications.
2. It explains transformers used in power plants along with their ratings, cooling methods, impedance and other details.
3. It covers transformer components, testing procedures, loading capacity, condition monitoring techniques and diagnostic tests to evaluate transformer performance and health.
The document is a presentation on the Liluah 132/33/25 KV substation in West Bengal. It includes acknowledgments, a single line diagram of the substation, and sections covering various equipment found at the substation like electrical busbars, protective relay schemes, lightning protection, isolators, capacitor banks, powerline carrier communication, batteries, earth transformers, traction transformers, station service transformers, and power transformers. Technical specifications are provided for some of the major equipment.
This document contains a presentation given by G Ravindra Kumar about his full semester internship training at GMR Kamalanga Energy Limited. The presentation discusses different types of switchgear including low voltage, medium voltage, and high voltage switchgear. It describes components of switchgear like circuit breakers, relays, current transformers, and details the operating principles and advantages of vacuum and air circuit breakers. Load details of various units of 6.6kV switchgear are also presented.
How is power transformer protected??? This provides a basic understanding of power transformer. Furthermore, the protective relay application on power transformer is included.
In-Country Training
On
Operation, Maintenance, Protection & Control of 33/11 kV Substation
Project Name: Design, Supply, Installation, Testing & Commissioning of 33/11 kV sub-stations with source end feeder bays.
Contract No: BREB/UREDS/W-01A-001/02/2016-2017
BREB/UREDS/W-01A-002/03/2016-2017
BREB/UREDS/W-01A-004/04/2016-2017
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.
The document discusses different types of circuit breakers, including air blast, vacuum, oil, and SF6 circuit breakers. It explains that a circuit breaker can make, carry, and break currents under normal and abnormal circuit conditions. The operating mechanism involves using stored energy to move a moving contact to open or close the circuit. When contacts separate during a fault, an arc is formed that must be quickly quenched for circuit interruption. Each breaker type uses a different medium, such as air, vacuum, oil or SF6 gas, to rapidly cool and extinguish the arc. Modern systems commonly use vacuum or SF6 breakers for their fast, reliable performance.
Installation Operation & Maintenance of 33kV & 11kV SwitchgearSheikh Nazmul Islam
In-Country Training On Operation, Maintenance, Protection & Control of 33/11 kV Substation Project Name: Design, Supply, Installation, Testing & Commissioning of 33/11 kV sub-stations with source end feeder bays. Contract No: BREB/UREDS/W-01A-001/02/2016-2017 BREB/UREDS/W-01A-002/03/2016-2017 BREB/UREDS/W-01A-004/04/2016-2017
The following topics are covered: components of power distribution systems, fuses, padmounted transformers, pole mounted transformers, vault installed transformers, transformer stations protection, transformer connections, thermometers, pressure relief devices, restricted ground faults, differential protection current transformers connections, overexcitation, inrush current, percentage differential relays, gas relays, characteristics of CTs.
This presentation summarizes the services of SDMI, a company that specializes in transformer maintenance. SDMI has the world's largest database of transformer test records, processes over 1 billion gallons of transformer oil, and performs over 300,000 oil samples annually. Their services include analytical testing of transformer oil and solid insulation, substation services, engineered products like oil reclamation systems, and PCB disposal. SDMI recommends routine oil testing to monitor aging and contamination, and diagnostic testing like dissolved gas analysis to identify abnormal transformer operation. Regular testing and maintenance can extend transformer life by removing degradation byproducts from the oil and paper insulation.
It is based on current transformer description
It's working and applications are present in it ,it also includes videos of it's windings and it's inrush ability of transformer, and also about instrument transformer and it's working with applications.Current transformers are used-in measuring high currents and connected with it in parallel to it
switchgear and protection by vala kamleshKamlesh Vala
Switchgear and protection systems play a vital role in modern power systems. Switchgear includes all switching devices associated with power system protection, control, metering and regulation. The main switching device is the circuit breaker. Circuit breakers can interrupt faults such as single line-to-ground faults, line-to-line faults, double line-to-ground faults, open circuit faults, and three phase faults. Circuit breakers use arc interruption to break current flow during opening of contacts. Common types of circuit breakers include oil, air, SF6, and vacuum circuit breakers. Switchgear equipment like fuses, circuit breakers, isolators, earthing switches, and current/potential transformers serve protection, control
Installation, Testing and Troubleshooting of TransformersLiving Online
The document discusses the installation, testing, and troubleshooting of transformers. It describes the different types of tests performed on transformers, including routine tests, type tests, and special tests. Routine tests check characteristics like winding resistance, voltage ratios, losses, and insulation. Special tests examine properties such as dielectric strength, capacitance, and harmonics. The document also outlines standards and procedures for testing, as well as limits for temperature rise and requirements for insulating oil.
Liquid Insulation Dissipation factor and Dielectric Factor Measurement UnitNadiiaHubar
The unit is designed for determining dielectric loss tangent and permittivity of transformer oils and other dielectric fluids according to the IEC 60247 and the corresponding national standards GOST 6581-75.
This document provides an executive summary of a 400kV switchyard project in Mundra, India. It includes lists of typical switchyard drawings, quality work being done on the switchyard including earthing and bolting, testing equipment being used, applications of equipment like CTs and isolators, the SCADA system, transformer oil standards, inspection procedures, stringing of transmission lines, project issues, documentation, and project management and quality management functions. Quality control tools mentioned include control charts.
This document discusses maintenance schedules and strategies for electrical substation equipment like power transformers and distribution transformers. It provides daily, monthly, quarterly, half-yearly, and annual maintenance tasks for checking equipment operation and performance. Key tasks include checking oil levels, insulation resistance, dissolved gases in oil, and cleaning/replacing oil filters. The document also summarizes common equipment defects like leaks, loose connections, and winding issues; and stresses on equipment from electrical, thermal, mechanical, and environmental factors that cause deterioration over time.
This document describes various protection schemes for transformers, including differential, restricted earth fault, overcurrent, and thermal protection.
1) Differential protection compares currents entering and leaving the transformer zone to detect internal faults. It provides the best protection for internal faults.
2) Restricted earth fault protection is used to detect high-resistance winding-to-core faults not detectable by differential relays. It uses a neutral current transformer and is sensitive to internal earth faults.
3) Overcurrent protection uses relays with current coils to detect overloads and faults above a pickup threshold. It also includes ground-fault protection.
High Voltage On-Site Testing with Partial Discharge Measurement (Cigre 502)AHMED MOHAMED HEGAB
During the life cycle of high voltage (HV) apparatus or systems many tests and measurements are performed to characterize the insulation condition. The results of these tests and
measurements should be compiled in a “life data record”, which supplies information on trends of diagnostic indicator values. The HV on-site test with partial discharge (PD) measurement has an intermediate position between routine tests and in-service monitoring measurements (on-line or offline)
Testing and Condition Monitoring of Substation EquipmentsSumeet Ratnawat
Testing and condition monitoring of substation equipments,Transformer specifications,Monitoring of Transformer,On-load Tap changer,Overhauling,Tan delta and capacitance,Thermal imaging,Sweep frequency response analysis,Oil analysis of Switchgear elements containing oil,tests on insulating oil,Breaker monitoring,Condition monitoring of CT,Condition monitoring of CVT,Surge Arresters,Condition monitoring of relays.
This Presentation is about l.v switch gear design, presented during the graduation project final discussion 15/7/2018.
It presented a good summary of switch gear components and types and practicing on AL.HAMOOL W.T.P M.D.B design using SIEMENS SIVACON S8
This document provides an overview of power transformers, including:
1. It describes different types of transformers such as power, distribution, auto, step-up, step-down transformers and discusses their various components and specifications.
2. It explains transformers used in power plants along with their ratings, cooling methods, impedance and other details.
3. It covers transformer components, testing procedures, loading capacity, condition monitoring techniques and diagnostic tests to evaluate transformer performance and health.
The document is a presentation on the Liluah 132/33/25 KV substation in West Bengal. It includes acknowledgments, a single line diagram of the substation, and sections covering various equipment found at the substation like electrical busbars, protective relay schemes, lightning protection, isolators, capacitor banks, powerline carrier communication, batteries, earth transformers, traction transformers, station service transformers, and power transformers. Technical specifications are provided for some of the major equipment.
This document contains a presentation given by G Ravindra Kumar about his full semester internship training at GMR Kamalanga Energy Limited. The presentation discusses different types of switchgear including low voltage, medium voltage, and high voltage switchgear. It describes components of switchgear like circuit breakers, relays, current transformers, and details the operating principles and advantages of vacuum and air circuit breakers. Load details of various units of 6.6kV switchgear are also presented.
How is power transformer protected??? This provides a basic understanding of power transformer. Furthermore, the protective relay application on power transformer is included.
In-Country Training
On
Operation, Maintenance, Protection & Control of 33/11 kV Substation
Project Name: Design, Supply, Installation, Testing & Commissioning of 33/11 kV sub-stations with source end feeder bays.
Contract No: BREB/UREDS/W-01A-001/02/2016-2017
BREB/UREDS/W-01A-002/03/2016-2017
BREB/UREDS/W-01A-004/04/2016-2017
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.
The document discusses different types of circuit breakers, including air blast, vacuum, oil, and SF6 circuit breakers. It explains that a circuit breaker can make, carry, and break currents under normal and abnormal circuit conditions. The operating mechanism involves using stored energy to move a moving contact to open or close the circuit. When contacts separate during a fault, an arc is formed that must be quickly quenched for circuit interruption. Each breaker type uses a different medium, such as air, vacuum, oil or SF6 gas, to rapidly cool and extinguish the arc. Modern systems commonly use vacuum or SF6 breakers for their fast, reliable performance.
Installation Operation & Maintenance of 33kV & 11kV SwitchgearSheikh Nazmul Islam
In-Country Training On Operation, Maintenance, Protection & Control of 33/11 kV Substation Project Name: Design, Supply, Installation, Testing & Commissioning of 33/11 kV sub-stations with source end feeder bays. Contract No: BREB/UREDS/W-01A-001/02/2016-2017 BREB/UREDS/W-01A-002/03/2016-2017 BREB/UREDS/W-01A-004/04/2016-2017
The following topics are covered: components of power distribution systems, fuses, padmounted transformers, pole mounted transformers, vault installed transformers, transformer stations protection, transformer connections, thermometers, pressure relief devices, restricted ground faults, differential protection current transformers connections, overexcitation, inrush current, percentage differential relays, gas relays, characteristics of CTs.
This presentation summarizes the services of SDMI, a company that specializes in transformer maintenance. SDMI has the world's largest database of transformer test records, processes over 1 billion gallons of transformer oil, and performs over 300,000 oil samples annually. Their services include analytical testing of transformer oil and solid insulation, substation services, engineered products like oil reclamation systems, and PCB disposal. SDMI recommends routine oil testing to monitor aging and contamination, and diagnostic testing like dissolved gas analysis to identify abnormal transformer operation. Regular testing and maintenance can extend transformer life by removing degradation byproducts from the oil and paper insulation.
It is based on current transformer description
It's working and applications are present in it ,it also includes videos of it's windings and it's inrush ability of transformer, and also about instrument transformer and it's working with applications.Current transformers are used-in measuring high currents and connected with it in parallel to it
switchgear and protection by vala kamleshKamlesh Vala
Switchgear and protection systems play a vital role in modern power systems. Switchgear includes all switching devices associated with power system protection, control, metering and regulation. The main switching device is the circuit breaker. Circuit breakers can interrupt faults such as single line-to-ground faults, line-to-line faults, double line-to-ground faults, open circuit faults, and three phase faults. Circuit breakers use arc interruption to break current flow during opening of contacts. Common types of circuit breakers include oil, air, SF6, and vacuum circuit breakers. Switchgear equipment like fuses, circuit breakers, isolators, earthing switches, and current/potential transformers serve protection, control
Installation, Testing and Troubleshooting of TransformersLiving Online
The document discusses the installation, testing, and troubleshooting of transformers. It describes the different types of tests performed on transformers, including routine tests, type tests, and special tests. Routine tests check characteristics like winding resistance, voltage ratios, losses, and insulation. Special tests examine properties such as dielectric strength, capacitance, and harmonics. The document also outlines standards and procedures for testing, as well as limits for temperature rise and requirements for insulating oil.
Liquid Insulation Dissipation factor and Dielectric Factor Measurement UnitNadiiaHubar
The unit is designed for determining dielectric loss tangent and permittivity of transformer oils and other dielectric fluids according to the IEC 60247 and the corresponding national standards GOST 6581-75.
This document provides an executive summary of a 400kV switchyard project in Mundra, India. It includes lists of typical switchyard drawings, quality work being done on the switchyard including earthing and bolting, testing equipment being used, applications of equipment like CTs and isolators, the SCADA system, transformer oil standards, inspection procedures, stringing of transmission lines, project issues, documentation, and project management and quality management functions. Quality control tools mentioned include control charts.
IRJET-Power Quality Improvement by using CHB Inverter based DVRIRJET Journal
This document discusses the design and analysis of a Dynamic Voltage Restorer (DVR) using a 7-level cascade H-bridge inverter to improve power quality. A DVR is a custom power device that injects voltage into the distribution system to regulate load voltage during sags or swells. This DVR employs a multilevel cascade H-bridge inverter which generates voltage waveforms with low harmonic distortion and connects directly to the network without a transformer. The performance of the DVR is analyzed in MATLAB and simulation results show it effectively compensates voltage sags and improves power quality for sensitive loads.
This report summarizes the author's activities while attached to the Harare Meter Test Depot. Key points include:
1. An overview of the metering department and its importance for revenue collection.
2. Details on replacing conventional electromechanical meters with modern digital prepaid meters to improve revenue and reduce non-payment.
3. An explanation of maximum demand metering using Enermax and Enermax-Plus meters for large commercial and industrial customers.
IRJET - Design of High Gain DC-DC Step Up ConverterIRJET Journal
The document describes a proposed high gain DC-DC step up converter. It consists of an interleaved boost stage with two inductors operated by two switches, and a voltage multiplier cell stage using diodes and capacitors to further increase the voltage gain. This provides high voltage gain with low voltage stress on components. It offers equal current sharing between the inductors, reducing conduction losses and improving efficiency compared to conventional interleaved boost converters. The proposed converter integrates coupled inductors and switched capacitors to achieve high step-up gain suitable for renewable energy applications.
A Three Phase AC-AC ZCS Resonant Converter for Induction HeatingIJMTST Journal
Generally, domestic induction-heating technology requires a high output power levels with less number of
components in a compact size. To satisfy these requirements, the basic circuit configurations are considered
based on the combination of a rectifier and a inverter. The main disadvantage of this method has low-efficient
and economic problems. This paper proposes a new concept unlike previous method, i.e the direct conversion
of ac–ac converter for reducing the component count, reduce cost, improve reliability, and also efficiency.
Generally, the proposed converter is a voltage-source based series-resonant converter used for controlling
output power, and minimizing the control complexity. This paper also proposes a concept of AC-AC converter
based three phase Induction Heating applications.
This document describes a thermistor temperature sensing alarm circuit. The circuit uses common electronic components like transistors, diodes, resistors and a buzzer to monitor temperature and raise an alarm if the temperature exceeds a set threshold. When the temperature increases, the resistance of the thermistor changes in a known way allowing the circuit to sense temperature changes. If the temperature goes above the threshold, the circuit activates the buzzer to alert the user. The circuit provides a low-cost solution for temperature monitoring in industrial and other applications.
This presentation discusses:
- Best practices regarding the need to ensure that all transformers used for metering circuits are properly sized
- The ability to optimize revenue regardless of customer usage over time
- Best practices to ensure that transformers and meters have been installed correctly in the field and continue to perform in the same fashion
- Best practices for certifying the accuracy class of the transformers and how to best set up a shop testing and field testing/verification program.
- What the costs of implementing such a system and what the costs of not implementing such a system can be.
IRJET- Generation and Control of Transient Overvoltages in Power System NetworksIRJET Journal
This document discusses the generation and control of transient overvoltages in power system networks. It begins by explaining that capacitor bank switching is a major cause of transient overvoltages and inrush currents. It then analyzes different techniques for mitigating these issues, including using pre-insertion resistors, current limiting reactors, and surge arresters. Through MATLAB simulations, it evaluates the effectiveness of each method at reducing peak transient voltages and currents. The surge arrester technique produced the best results, lowering transient overvoltages to 0.64 p.u. and inrush currents to 0.794 kA when connected phase to neutral at the capacitor bank. In conclusion, controlling transients through various techniques can improve power quality and distribution system performance
Part II also includes admittance and demag testing and uses more advanced equipment to test the meter. See live results from today’s newest test equipment.
IRJET- Comparison of H5 and HERIC Trasformerless Inverter Topology Conserning...IRJET Journal
This document compares the H5 and HERIC transformerless inverter topologies used in photovoltaic systems for their leakage current and efficiency. It finds that the HERIC topology has lower conduction losses than the H5 topology due to differences in switching behavior. The HERIC topology also produces less leakage current than the H5. Both topologies require similar sized filters to cancel output harmonics. In conclusion, the HERIC topology performs better in terms of losses and leakage current reduction compared to the H5 topology for photovoltaic inverters.
This document discusses an interleaved boost converter that can achieve high voltage conversion ratios and efficiency. It begins by introducing the need for high step-up DC-DC converters in applications like renewable energy systems. It then describes the structure and operation of an interleaved boost converter, which can reduce input current ripples and output voltage ripples through phase shifting between units. The document outlines the various operating states of the interleaved boost converter and considerations for designing it, such as duty cycle and component sizing. It presents simulation results showing the current through the inductors. The conclusion states that interleaved boost converters can provide higher voltage gains and lower switching losses compared to conventional boost converters.
Limitations of DC injection into the AC network is an important operational requirement for grid connected photovoltaic systems. There is one way to ensure that this issue needs a power transformer as a connection to the AC network. However, this solution adds cost, volume, mass, and power losses. Ideally there shouldn't be any DC at the output of the inverter, but practically, a small amount of DC current is present. Therefore, in this paper there are techniques for the DC offset elimination are proposed. Some have drawbacks which was treated by another technique. Also there are best solutions for eliminating DC offset as in section 17, and 18 as it explains how to reduce the DC offset in a transformerless operation with reducing the power losses, mass and the cost effect.
Closed Loop Simulation and Implementation of Digital Integral Control of Sy...IRJET Journal
1) The document describes the closed-loop simulation and implementation of a digital integral controller for a synchronous buck converter.
2) A synchronous buck converter uses two MOSFET switches instead of a diode and switch to improve efficiency. It was modeled and simulated in MATLAB/Simulink.
3) The digital controller uses an ADC, digital compensator, and DPWM to regulate the output voltage against input voltage and load current variations. Simulation results show the converter steps down the input voltage as expected.
IRJET- Interleaved DC-DC Boost Converter with High Voltage Gain and Effic...IRJET Journal
The document describes an interleaved boost converter design for solar energy systems that achieves high voltage gain and efficiency. The interleaved topology minimizes ripple current and losses by operating switches out of phase. It utilizes a coupled inductor and voltage multiplier circuit to boost a 12V input to 100V output. Maximum power point tracking with fuzzy logic is used to optimize solar energy extraction. Simulation results show the converter can achieve its design goals of high output voltage and fast battery charging performance compared to conventional boost converters.
1. The document discusses control strategies for EHV AC and DC transmission systems, including desired features of HVDC system control, control characteristics of constant current and constant extinction angle, and parallel operation of AC and DC systems.
2. Control of HVDC systems is achieved through control of current or voltage to maintain a constant voltage in the DC link. Common control modes include constant current control at the rectifier and constant extinction angle control at the inverter.
3. Parallel operation of AC and DC systems can present problems but also advantages; control coordination is needed between the two different transmission types.
The document discusses networked control and power management in AC/DC hybrid microgrids. Key points include:
1) Cooperative control is proposed where converters take decentralized control decisions based on local measurements but cooperate through communication to balance system variables and ensure stability even if communication links fail.
2) Stability analysis is performed using small-signal modeling and averaging of the converter. Routh-Hurwitz criterion is used to check stability of the complete system including input filter.
3) Sensitivity analysis is done to study the effect of parameter variations on stability using a Lyapunov function approach, showing the system remains locally asymptotically stable under certain conditions.
Closed Loop Analysis of Multilevel Inverter Fed Drives IJPEDS-IAES
This paper deals with the simulation and implementation of multilevel inverter for drives application. Here the focuses will be onimproving the efficiency of the multilevel inverter and quality of output voltage waveform. The circuit is developed towards high efficiency, high performance, and low cost, simple control scheme. Harmonics Elimination was implemented to reduce the Total Harmonics Distortion (THD) value which is achieved by selecting appropriate switching angles. In this paper to determine the performance of rectifier, steady state analysis is done. Furthermore, the merits of multilevel inverter topology are inherited.Closed loop control is done to analysis the stability of the system.
IRJET- Modified Cascaded H - Bridge Multilevel Inverter for Household AppliancesIRJET Journal
This document describes a study on a modified cascaded H-bridge multilevel inverter for household appliances. The researchers developed a 9-level single phase inverter using 4 H-bridge cells. They used sinusoidal pulse width modulation to generate switching signals and reduce harmonic distortion. Simulations in MATLAB/Simulink showed the output voltage waveform and total harmonic distortion of 9.12%. A hardware prototype was built and tested to verify the design, demonstrating a 53.9V output voltage with 8.22% total harmonic distortion. The modified topology reduces switching losses and improves output capability compared to other multilevel inverter configurations.
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Online Condition Monitoring And Diagnosis Of Power Transformers Their Bushings ,Tap Changer And Insulation System
1. EEE Dept. CBIT, Hyderabad
EEE Dept. CBIT, Hyderabad
1-Jun-21 1
1
SEMINAR PRESENTATION
DEPARTMENT OF ELECTRICAL AND ELECTRONICS ENGINEERING
CHAITHANYA BHARATHI INSTITUTE OF TECHNOLOGY
GANDIPET, HYDERABAD
2014
Submitted by
K .V. V. Satyanarayana
Roll No: 1601-14-766-006
M. E (Power Systems & Power Electronics)
2. EEE Dept. CBIT, Hyderabad
EEE Dept. CBIT, Hyderabad
CONTENTS
1. Introduction
2. Bushings
3.System Description
4. Bushing monitoring
4.1.Capacitively controlled insulator bushings
4.2.Bushing capacitance C and dielectric dissipation factor tanδ.
4.3.Voltage sensor
4.4.Operating voltages and overvoltages
4.5Bush Capacitance
4.6.Dielectric dissipation factor tan δ and sum phasor
4.7.Bushing oil pressure
5.Insulation System And Tap Changer
6 Reference
1-Jun-21 2
3. EEE Dept. CBIT, Hyderabad
EEE Dept. CBIT, Hyderabad
I. INTRODUCTION
• A bushing must be designed to withstand the electrical field
strength produced in the insulation, when any earthed material is
present
• In a Oil-filled power transformers, their bushings, tap changer,
insulation system and auxiliary equipment are critical to the
operation of every electrical power system to such an extend that
their reliable and uninterrupted functioning is a key factor in
profitable generation, transmission and distribution.
• Recent years on-line monitoring systems have been installed in a
large scale at power transformers.
7. EEE Dept. CBIT, Hyderabad
EEE Dept. CBIT, Hyderabad
• The utilities network (Ethernet) can
transport the information from the
substation to every PC (web based
visualization)
• Starting from the strict point of view
of monitoring it is then proceed
forward with the presentation of
diagnostics, prognosis is done.
• The task of on-line monitoring is
then to provide focused, purposeful
diagnosis information, so that
remedial measures can be initiated if
needed should faults occur during
operation.
On-line visualization of transformer condition and its
information about trending, diagnostics and prognostics
8. EEE Dept. CBIT, Hyderabad
EEE Dept. CBIT, Hyderabad
II. SYSTEM DESCRIPTION
On-line monitoring system is employed
1. Ageing rate,
2. Overloading condition,
3. Change in the bushing capacitance
• Data acquisition is time-controlled and event controlled.
Thus,when a transformer is switched on, the voltages are recorded
for a duration of 10 seconds with a resolution of 20 ms.
• In comparison, the changes in the bushing capacitance are
sampled every 20 ms and saved every 15 minutes consequently the
size of the database is optimized.
9. EEE Dept. CBIT, Hyderabad
EEE Dept. CBIT, Hyderabad
A. Capacitively controlled insulator bushings
• In the voltage range from 110 kV upwards, modern bushings
are generally designed with closely stepped capacitive control
layers.
• Basic insulating systems of capacitive controlled high voltage
bushings can be classified as:
1. Resin-bonded paper bushings (RBP)
2. Resin-impregnated paper bushings (RIP)
3. Oil-impregnated paper bushings (OIP)
10. EEE Dept. CBIT, Hyderabad
EEE Dept. CBIT, Hyderabad
Bushing capacitance C and dielectric dissipation
factor (tan δ)
• Measurement of the bushing capacitance C and the dielectric
dissipation factor tan δ are important parameters for
evaluating the operational state of a high voltage bushing.
• dissipation factor
tan δ = 1/R C.
• Range of tan δ for normal operation
new resin-bonded paper bushing, it is in the range 0.5 ... 0.7 %.
resin-impregnated bushings, it is in the range 0.25 ... 0.45 %
oil-impregnated bushings, values between 0.25 ... 0.5%
11. EEE Dept. CBIT, Hyderabad
EEE Dept. CBIT, Hyderabad
Equivalent circuit diagram and vector diagram of
the dielectric loss factor tan δ
12. EEE Dept. CBIT, Hyderabad
EEE Dept. CBIT, Hyderabad
• Dielectric losses in the insulation result in a capacitive loss
current in the dielectric material.
• Depending on the ageing, the bushing capacitance and the tan
δ can change.
• Table below shows guide values for tan δ and capacitance
values as examples for resin bonded paper bushings.
• When these limiting values are reached, continued operation
is not recommended.
13. EEE Dept. CBIT, Hyderabad
EEE Dept. CBIT, Hyderabad
• Reasons for a change in the values of tan δ and ∆ C
External influences : moisture and dirt on the porcelain.
∆ C can also be caused by an oil-impregnation in the
case of resin-bonded paper bushings.
• Increase in the ∆ C for all bushing types indicates partial
breakdowns between control layers
14. EEE Dept. CBIT, Hyderabad
EEE Dept. CBIT, Hyderabad
C. Voltage sensor
• The monitoring of the electrical measurement quantities is achieved
with a voltage sensor . The sensor is connected directly to the
measurement tap of the bushing . This design allows a reliable
measurement with a bandwidth of up to 2 MHz
Bushing
Bushing voltage sensors installed on the
measurement tap of the bushings
15. EEE Dept. CBIT, Hyderabad
EEE Dept. CBIT, Hyderabad
• The sensor essentially consists of
capacitor Cm, which normally has values of 1 .. 2 µF.
1. Cm >> C2 (i.e C2 ≈ 300 pF), I2 is practically 0.
2. R terminates the coaxial cable with a surge impedance of 50 Ω.
3. potential divider ratio between C1 and CM is so dimensioned that a
measurement voltage Um of 57 V AC is set.
4. overvoltage suppressor (Ü) installed, which protects the sensor and
the cable from overvoltages, and as there are no electronic
components used in the sensor at the bushing, this measurement
procedure is not sensitive to electromagnetic emission.
16. EEE Dept. CBIT, Hyderabad
EEE Dept. CBIT, Hyderabad
Case study-1:
Three-phase operating voltages on the 275 kV bushings of a 185
MVA generator transformer together with detected overvoltages
recorded over a period of 18 months.
present-day technology easily allows the continuous acquisition
and archiving of all the data even for longer than 18 months,
across many years (life).
Continuously monitored
3-phase operating
voltages (phases L1, L2,
L3) with overvoltages,
voltage fluctuations and
network asymmetries
17. EEE Dept. CBIT, Hyderabad
EEE Dept. CBIT, Hyderabad
Bushing capacitance
• Monitoring of the change in the bushing capacitances (∆ C)
is achieved by means of a three-phase voltage
measurement.the output signal of a voltage sensor is
compared with the two remaining phases.
• In consequence, the relative change in capacitance is used
for determining the ∆ C.
18. EEE Dept. CBIT, Hyderabad
EEE Dept. CBIT, Hyderabad
• Case study 2:
• The effect of a partial flashover of 2 layers of a 420 kV
bushing is depicted in 3-phase operating voltages (phase
L1, L2, L3) together with overvoltage's of the 350 MVA
regulating transformer.
• After only 1 ½ years of bushing operation a warning was
generated automatically by the on-line monitoring system.
1-Jun-21 18
Detection of partial
flashover of 420 kV bushing
and avoidance of collateral
damage of 350 MVA
regulating transformer, 3-
phase operating voltages
(phase L1, L2, L3) with
overvoltages identified by
change of capacitance ∆ C
19. EEE Dept. CBIT, Hyderabad
EEE Dept. CBIT, Hyderabad
Dielectric dissipation factor tan δ and sum phasor
• The measurement of the phase angle between the three phases
makes it possible to detect changes in the dielectric dissipation
(loss) factor tan δ.
• The difficulty in the measurement technique is in being able
to detect even very slight changes.
• A change in the loss factor tan δ by 0.1 % means that the phase
changes by an angle of 0.057 °.
• The measurement data has to be recorded with a very high
resolution in terms of time in order to achieve this accuracy.
• In this case, the sampling rate is 10 µs, to detect the zero
crossing of the 50/60 Hz AC voltage.
• In addition, the evaluation algorithm carries out an
interpolation to achieve further improvement in the accuracy.
20. EEE Dept. CBIT, Hyderabad
EEE Dept. CBIT, Hyderabad
• For the acquisition of the ∆ tan δ, an accuracy of at least ± 0.15
% must be reached.
• The reason for this is that the dissipation factor for the various
types of construction of bushings moves in the range of about 0.5
% and a maximum warning threshold has to be assumed at about
0.7 %.
• In on-line measurement, as in the process described here, the
voltage of another phase is used as a reference.
21. EEE Dept. CBIT, Hyderabad
EEE Dept. CBIT, Hyderabad
• Different types of interpretation methods (change of
dissipation factor vs. sum current phasor) with their
advantages and disadvantages are discussed
• Therefore, a depiction of the sum vector in a polar diagram as
suggested in does not appear very meaningful.
• A better interpretation of the data is achieved by depicting the
change in the dissipation factor
Polar diagram of the sum
vector of a 3-phase bushing
monitoring on a 400 kV
generator transformer
22. EEE Dept. CBIT, Hyderabad
EEE Dept. CBIT, Hyderabad
G. Bushing oil pressure
• For oil-filled bushings, it is possible to measure the
bushing oil pressure, thus detecting possible oil leaks.
• Reason for changes in the bushing oil pressure is
thermal overload,
partial discharges.
3-phase monitoring of
the change in the
bushing oil pressure on
a 400 kV agenerator
transformer with
detection of an oil leak
on phase L1
23. EEE Dept. CBIT, Hyderabad
EEE Dept. CBIT, Hyderabad
INSULATION SYSTEM AND TAP CHANGER
• To monitor the condition of the active part of a power transformer
various measurement and analysing quantities can be realised. As
main parameters are to
1. Mention temperatures,
2. Loading conditions,
3. Gas-in oil content,
4. Moisture of oil and paper insulation system.
24. EEE Dept. CBIT, Hyderabad
EEE Dept. CBIT, Hyderabad
case study 3:
• A 75 MVA furnace transformer was put in service in a
steelworks factory. the 75 MVA furnace together with two
more transformers of this site were equipped with an MS 2000
on-line monitoring system the recommendations of MS 2000 a
DGA was performed and indicated the presence of a hot-spot.
• when the gas-in-oil content crossed the 1000 ppm limit the
transformer tripped through the Buchholz relay with a
collateral damage.
25. EEE Dept. CBIT, Hyderabad
EEE Dept. CBIT, Hyderabad
CONCLUSION :
• By on-line condition monitoring and diagnosis we can realize and demonstrate
how capacitively controlled bushings can be monitored on-line in a simple
manner.
• The change in the bushing capacitance as the most important characteristic
quantity for determining the operational state can be analyzed reliably on this
basis.
• A critical damage of a 350 MVA grid coupling transformer could be avoided.
Another collateral damage could be prevented by detection of an oil leak on a 185
MVA generator transformer by means of monitoring the bushing oil pressure.
• Furthermore a 75 MVA furnace transformer has demonstrated the detection of its
condition from beginning of a fault until collateral damage. It has been
demonstrated that the operating condition of the transformer can be made
transparent with the use of an on-line monitorings
• Overally the malfunctions that are building up in power transformers can be
detected earlier with the deployment of an efficient on-line monitoring system and
as a result, there is a lower potential for transformer endangerment. g therefrom,
overvoltage's and transient voltages can be detected.
26. EEE Dept. CBIT, Hyderabad
EEE Dept. CBIT, Hyderabad
REFERENCES
• http://www.google.com/online condition monitoring and diagnosis of
power transformers their bushings .tap changers and insulation system
”, IEEE Power Engineering Society Winter Meeting, Columbus, Ohio,
2001
• http://www.inmr.com/2014/02/brazilian-research-centre-develops-
software-tools-diagnostic-tests-network-components/4/
• http://www.google.co.in/search?q=transformer+bushing+damage&safe
=active&biw=400&bih=609&source=lnms