Matched-melt coordination as defined in IEEE C37.48 is a variation of time-current curve coordination that is used to ensure that the expulsion fuse melts open during any overload or fault condition.
Distribution Transformer Manufacturing at Navana Electronics ltd (Aliv)Md Abu Jauad Khan Aliv
Navana Electronics Ltd (NEL) manufactures distribution transformers at their factory in Dhaka, Bangladesh. The manufacturing process begins with cutting and assembling the core using silicon steel laminations. Windings are then wound on the core and insulated using cotton tape, press board, and kraft paper. The assembled core and coils are dried in a vacuum chamber then submerged in transformer oil inside a tank. Additional components like bushings, radiators, and tap changers are added. Testing includes insulation, ratio, polarity, no-load, and short-circuit tests before transformers are dispatched. The presentation recommends improving facilities for training, separation of production rooms, and a more modern working environment.
Tan δ (delta) testing measures the dissipation factor of cable insulation to determine quality and predict remaining life. It works by applying a very low frequency AC voltage and measuring the phase shift between the voltage and current, which indicates the ratio of resistive to capacitive current through the insulation. Higher phase shift angles mean more defects in the insulation. While no set standards exist, utilities can use comparative tan δ testing over time to prioritize cable replacement. The test is inexpensive, easy to perform, and can evaluate long cable runs using specialized very low frequency AC hipots.
This document provides information about transformer tests conducted at BEST Balıkesir Transformer Factory laboratories. It describes routine tests like winding resistance measurement, voltage ratio measurement and phase checking, as well as type tests and special tests. The routine tests section explains test procedures and equipment for various tests done on all transformers produced. These include impedance measurement, no-load loss tests, and tap changer tests. Type and special tests involve temperature rise testing, lightning impulse testing, and other advanced analyses. Laboratory equipment for performing over a dozen transformer tests is also listed.
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.
This document discusses testing of transformers. It provides an overview of transformers and their functions in transmission and distribution of electrical energy. It then describes various routine, type, and special tests performed on transformers, including winding resistance measurement, voltage ratio measurement, no-load loss measurement, load loss measurement, insulation resistance measurement, and dielectric tests. It also discusses short-circuit testing procedures and criteria. Temperature rise testing and its limits are also summarized.
This document discusses switchgear, its types and components, as well as maintenance procedures. It begins by defining switchgear and its purposes of controlling, protecting and isolating electrical equipment. It then discusses low voltage and medium voltage switchgear, and lists the basic functions of switchgear as electrical protection, safe isolation from live parts, and local or remote switching. The document goes on to discuss periodic and preventive maintenance of switchgear.
The document discusses distribution transformers, including their testing, maintenance, and protection. It provides details on routine tests, type tests, and special tests performed on transformers according to standards. These tests check various parameters like winding resistance, insulation levels, voltage ratios, losses, and short circuit withstand ability. The document also outlines maintenance procedures like regular oil testing, insulation resistance checks, bushing cleaning, and temperature monitoring. Proper preventive maintenance is emphasized to prevent failures caused by issues like low oil levels, water ingress, overloading, and poor design/workmanship.
This document provides information on various types of protective devices used in electrical systems, including fuses, MCBs, ELCBs, MCCBs, RCCBs, SFUs, breakers, RTDs, thermistors, thermocouples, and relays. It also discusses the ratings and applications of these devices for protecting transformers, motors, cables, busbars, and feeders from overcurrent, earth faults, overheating, undervoltage, and other hazards. Recommendations are given for the appropriate protective devices based on equipment ratings like KVA and motor power.
Distribution Transformer Manufacturing at Navana Electronics ltd (Aliv)Md Abu Jauad Khan Aliv
Navana Electronics Ltd (NEL) manufactures distribution transformers at their factory in Dhaka, Bangladesh. The manufacturing process begins with cutting and assembling the core using silicon steel laminations. Windings are then wound on the core and insulated using cotton tape, press board, and kraft paper. The assembled core and coils are dried in a vacuum chamber then submerged in transformer oil inside a tank. Additional components like bushings, radiators, and tap changers are added. Testing includes insulation, ratio, polarity, no-load, and short-circuit tests before transformers are dispatched. The presentation recommends improving facilities for training, separation of production rooms, and a more modern working environment.
Tan δ (delta) testing measures the dissipation factor of cable insulation to determine quality and predict remaining life. It works by applying a very low frequency AC voltage and measuring the phase shift between the voltage and current, which indicates the ratio of resistive to capacitive current through the insulation. Higher phase shift angles mean more defects in the insulation. While no set standards exist, utilities can use comparative tan δ testing over time to prioritize cable replacement. The test is inexpensive, easy to perform, and can evaluate long cable runs using specialized very low frequency AC hipots.
This document provides information about transformer tests conducted at BEST Balıkesir Transformer Factory laboratories. It describes routine tests like winding resistance measurement, voltage ratio measurement and phase checking, as well as type tests and special tests. The routine tests section explains test procedures and equipment for various tests done on all transformers produced. These include impedance measurement, no-load loss tests, and tap changer tests. Type and special tests involve temperature rise testing, lightning impulse testing, and other advanced analyses. Laboratory equipment for performing over a dozen transformer tests is also listed.
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.
This document discusses testing of transformers. It provides an overview of transformers and their functions in transmission and distribution of electrical energy. It then describes various routine, type, and special tests performed on transformers, including winding resistance measurement, voltage ratio measurement, no-load loss measurement, load loss measurement, insulation resistance measurement, and dielectric tests. It also discusses short-circuit testing procedures and criteria. Temperature rise testing and its limits are also summarized.
This document discusses switchgear, its types and components, as well as maintenance procedures. It begins by defining switchgear and its purposes of controlling, protecting and isolating electrical equipment. It then discusses low voltage and medium voltage switchgear, and lists the basic functions of switchgear as electrical protection, safe isolation from live parts, and local or remote switching. The document goes on to discuss periodic and preventive maintenance of switchgear.
The document discusses distribution transformers, including their testing, maintenance, and protection. It provides details on routine tests, type tests, and special tests performed on transformers according to standards. These tests check various parameters like winding resistance, insulation levels, voltage ratios, losses, and short circuit withstand ability. The document also outlines maintenance procedures like regular oil testing, insulation resistance checks, bushing cleaning, and temperature monitoring. Proper preventive maintenance is emphasized to prevent failures caused by issues like low oil levels, water ingress, overloading, and poor design/workmanship.
This document provides information on various types of protective devices used in electrical systems, including fuses, MCBs, ELCBs, MCCBs, RCCBs, SFUs, breakers, RTDs, thermistors, thermocouples, and relays. It also discusses the ratings and applications of these devices for protecting transformers, motors, cables, busbars, and feeders from overcurrent, earth faults, overheating, undervoltage, and other hazards. Recommendations are given for the appropriate protective devices based on equipment ratings like KVA and motor power.
Transformers are an essential part of the electricity network: they convert electrical energy from one voltage level to another. This course is introducing the subject of transformers. The intention of the whole series is to promote lifecycle thinking when procuring transformers. Therefore, the focus will be on energy performance, reliability, asset management
Tan delta is the insulation power factor & is equal to the ratio of power dissipated in the insulation in watts to the product of effective voltage & current in volt ampere when tested under sinusoidal voltage.
The document discusses circuit breakers, including their technical aspects, types, fundamental characteristics, parts, and comparisons to other switching devices. It describes circuit breaker ratings like voltage, current, and short circuit levels. Common circuit breaker types include air magnetic, oil, air blast, vacuum, and SF6 gas. The document also outlines selection criteria for low and medium-high voltage switching devices and reviews circuit breaker control circuits, interlocks, and SF6 circuit breakers.
This document provides information about transformers, including power and distribution transformers. It discusses core types, windings, cooling systems, installation locations, voltage ratings, and capacities. The document compares power and distribution transformers and describes their different parts. It also outlines the design process for transformers, listing specifications, calculations, and performance testing according to IEC standards.
This document analyzes grounding considerations for large kVA pad-mount transformers. It summarizes the assumptions made in analyzing different transformer voltages and kVA sizes up to 5,000 kVA. Calculations of ground potential rise, touch potential and step potential are performed and compared to safety limits. Results show the standard two ground rod system may not provide adequate protection for transformers over 750 kVA or higher secondary voltages. Larger or engineered grounding systems are recommended for safety.
This document discusses Sumpner's test, which is used to determine the regulation and efficiency of large power transformers. Sumpner's test involves connecting two identical transformers back-to-back, with their primaries in parallel and secondaries in series opposition. This allows them to be tested at full load conditions without actual loading. The test provides accurate measurements of total losses, including both iron and copper losses occurring simultaneously as in actual use. Its advantages are that it requires little power and tests transformers under full load conditions. The limitation is that it requires two identical transformers.
Description of Auto-Transformer working principle,Constructional features of Auto transformer,Advantages of Auto transformer,Inductional law in Auto transformer,copper saving advantage in Auto transformer,Types of Auto transformer,Conversion of two-winding transformet to Auto transformer,Disadvantages of Auto transformer,Applications of Auto transformer,Limitations of Auto transformer.
Test done on Power transformers.
Insulation Resistance test, Winding Resistance test, Ratio Measurements, Magnetic balance test, Tan delta test, DIssolved gas analysis for transformer, Sweep frequency response analysis.
How is power transformer protected??? This provides a basic understanding of power transformer. Furthermore, the protective relay application on power transformer is included.
The document discusses short circuit currents and testing of transformers to withstand short circuits. It defines short circuits and short circuit current, and differentiates short circuits from overloads. Symmetrical and asymmetrical short circuit currents are calculated. Short circuit tests are done on distribution and power transformers to demonstrate their ability to withstand thermal and dynamic effects of short circuits without damage. The document outlines test procedures, current calculations, and setup for short circuit testing in the lab.
This document summarizes a student project on assessing the life of transformers. It describes the objectives of understanding transformers in detail and studying tests to assess transformer health. It then provides details on different transformer types and components like bushings and accessories. The document outlines transformer design considerations and tests conducted at different stages like preliminary, commissioning and special tests. It discusses techniques like dissolved gas analysis and furan analysis used to monitor transformer condition and residual life.
HIGH VOL TAGE TESTING OF TRANSFORMER BY HARI SHANKAR SINGHShankar Singh
1. The document discusses high voltage testing of electrical transformers, including various types of tests like partial discharge testing, impulse testing, turns ratio testing, and insulation resistance testing.
2. These tests help check the insulation quality, detect defects, verify voltage ratios, and ensure transformers can withstand high voltage surges to prevent failures.
3. High voltage testing provides advantages like improved safety, energy efficiency, lower costs, and failure detection; but can also have disadvantages like not removing the root causes of failures.
The document discusses the loss tangent delta (tan δ) test, which is used to detect deviations in the insulation of rotating machines during their service lifetime. Tan δ is a ratio that measures the loss component versus the capacitive component of current in an insulation. It increases with temperature and applied voltage. Periodic tan δ measurements are recommended to monitor changes from the baseline reading, as increases could indicate deterioration of the insulation system. The test procedure, safety precautions, and interpretation of results are described.
Relays sense abnormal voltage and current conditions and send signals to circuit breakers to isolate faulty parts of a power system. Electromagnetic induction relays use eddy currents produced in a disc to generate torque. There are different types of overcurrent and directional relays. Distance relays use impedance, reactance, or mho principles. Transformer and feeder protection uses overcurrent, distance, or pilot wire schemes. Circuit breakers use oil, air, sulfur hexafluoride, or vacuum to extinguish arcs and open faulty circuits. Instrument transformers reduce high voltages and currents to safer, measurable levels for meters and relays.
Feel free to buy low voltage switchgear in eleczo.com- one of the leading online websites in india. We supply and distribute all low voltage switch gear in india.
The purpose of the test is to secure that the transformer insulations withstand the lightning overvoltages which may occur in service.The testing is conducted by artificial generation oflightning impulse using IMPULSe GENERATORS
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.
This document describes a circuit that can detect air flow using an incandescent light bulb filament. The filament acts as a sensor, with its resistance dropping when air flows over it due to convective cooling. This resistance change is amplified by an LM339 operational amplifier and used to vary the brightness of an LED, providing a visual indication of the air flow rate. The circuit also includes voltage regulators to provide stable power and can be used to detect air flow in industrial, medical, or automotive applications.
open circuit and short circuit test on transformerMILAN MANAVAR
This document describes open circuit and short circuit tests performed on transformers. The open circuit test is done to measure iron losses by connecting meters to the primary side with the secondary open. The short circuit test is done to measure copper losses by shorting the secondary and applying a small voltage to the primary side. These tests allow determining key transformer parameters like losses and efficiency without actual loading and are economical and convenient.
This document provides information about transformers, including their components, principles of operation, and applications. It discusses how transformers transfer electrical energy from one circuit to another through electromagnetic induction, changing the voltage and current magnitudes but not the frequency. The key components are the core, primary winding, and secondary winding. Transformers operate based on the principle of mutual induction between the windings. They are used in various applications like power transmission and audio/radio frequencies.
The document discusses the unique role and design requirements of wind turbine step-up (WTSU) transformers. WTSU transformers differ from conventional distribution transformers and generator step-up transformers in several key ways. They experience wide variations in loading from intermittent wind, harmonic loads from electronic controls, must be sized without overload capacity, and must withstand faults while wind turbines remain connected to the grid. As a result, the document argues that WTSU transformers require a uniquely robust design that is tailored to their operating conditions and is not suited for conventional "off the shelf" transformers.
Harnessing wind energy to perform work is not a new concept.
Since the earliest of times, wind power has captured with sails to allow traders, merchants and explorers to ply their trades and discover the world around them.
Transformers are an essential part of the electricity network: they convert electrical energy from one voltage level to another. This course is introducing the subject of transformers. The intention of the whole series is to promote lifecycle thinking when procuring transformers. Therefore, the focus will be on energy performance, reliability, asset management
Tan delta is the insulation power factor & is equal to the ratio of power dissipated in the insulation in watts to the product of effective voltage & current in volt ampere when tested under sinusoidal voltage.
The document discusses circuit breakers, including their technical aspects, types, fundamental characteristics, parts, and comparisons to other switching devices. It describes circuit breaker ratings like voltage, current, and short circuit levels. Common circuit breaker types include air magnetic, oil, air blast, vacuum, and SF6 gas. The document also outlines selection criteria for low and medium-high voltage switching devices and reviews circuit breaker control circuits, interlocks, and SF6 circuit breakers.
This document provides information about transformers, including power and distribution transformers. It discusses core types, windings, cooling systems, installation locations, voltage ratings, and capacities. The document compares power and distribution transformers and describes their different parts. It also outlines the design process for transformers, listing specifications, calculations, and performance testing according to IEC standards.
This document analyzes grounding considerations for large kVA pad-mount transformers. It summarizes the assumptions made in analyzing different transformer voltages and kVA sizes up to 5,000 kVA. Calculations of ground potential rise, touch potential and step potential are performed and compared to safety limits. Results show the standard two ground rod system may not provide adequate protection for transformers over 750 kVA or higher secondary voltages. Larger or engineered grounding systems are recommended for safety.
This document discusses Sumpner's test, which is used to determine the regulation and efficiency of large power transformers. Sumpner's test involves connecting two identical transformers back-to-back, with their primaries in parallel and secondaries in series opposition. This allows them to be tested at full load conditions without actual loading. The test provides accurate measurements of total losses, including both iron and copper losses occurring simultaneously as in actual use. Its advantages are that it requires little power and tests transformers under full load conditions. The limitation is that it requires two identical transformers.
Description of Auto-Transformer working principle,Constructional features of Auto transformer,Advantages of Auto transformer,Inductional law in Auto transformer,copper saving advantage in Auto transformer,Types of Auto transformer,Conversion of two-winding transformet to Auto transformer,Disadvantages of Auto transformer,Applications of Auto transformer,Limitations of Auto transformer.
Test done on Power transformers.
Insulation Resistance test, Winding Resistance test, Ratio Measurements, Magnetic balance test, Tan delta test, DIssolved gas analysis for transformer, Sweep frequency response analysis.
How is power transformer protected??? This provides a basic understanding of power transformer. Furthermore, the protective relay application on power transformer is included.
The document discusses short circuit currents and testing of transformers to withstand short circuits. It defines short circuits and short circuit current, and differentiates short circuits from overloads. Symmetrical and asymmetrical short circuit currents are calculated. Short circuit tests are done on distribution and power transformers to demonstrate their ability to withstand thermal and dynamic effects of short circuits without damage. The document outlines test procedures, current calculations, and setup for short circuit testing in the lab.
This document summarizes a student project on assessing the life of transformers. It describes the objectives of understanding transformers in detail and studying tests to assess transformer health. It then provides details on different transformer types and components like bushings and accessories. The document outlines transformer design considerations and tests conducted at different stages like preliminary, commissioning and special tests. It discusses techniques like dissolved gas analysis and furan analysis used to monitor transformer condition and residual life.
HIGH VOL TAGE TESTING OF TRANSFORMER BY HARI SHANKAR SINGHShankar Singh
1. The document discusses high voltage testing of electrical transformers, including various types of tests like partial discharge testing, impulse testing, turns ratio testing, and insulation resistance testing.
2. These tests help check the insulation quality, detect defects, verify voltage ratios, and ensure transformers can withstand high voltage surges to prevent failures.
3. High voltage testing provides advantages like improved safety, energy efficiency, lower costs, and failure detection; but can also have disadvantages like not removing the root causes of failures.
The document discusses the loss tangent delta (tan δ) test, which is used to detect deviations in the insulation of rotating machines during their service lifetime. Tan δ is a ratio that measures the loss component versus the capacitive component of current in an insulation. It increases with temperature and applied voltage. Periodic tan δ measurements are recommended to monitor changes from the baseline reading, as increases could indicate deterioration of the insulation system. The test procedure, safety precautions, and interpretation of results are described.
Relays sense abnormal voltage and current conditions and send signals to circuit breakers to isolate faulty parts of a power system. Electromagnetic induction relays use eddy currents produced in a disc to generate torque. There are different types of overcurrent and directional relays. Distance relays use impedance, reactance, or mho principles. Transformer and feeder protection uses overcurrent, distance, or pilot wire schemes. Circuit breakers use oil, air, sulfur hexafluoride, or vacuum to extinguish arcs and open faulty circuits. Instrument transformers reduce high voltages and currents to safer, measurable levels for meters and relays.
Feel free to buy low voltage switchgear in eleczo.com- one of the leading online websites in india. We supply and distribute all low voltage switch gear in india.
The purpose of the test is to secure that the transformer insulations withstand the lightning overvoltages which may occur in service.The testing is conducted by artificial generation oflightning impulse using IMPULSe GENERATORS
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.
This document describes a circuit that can detect air flow using an incandescent light bulb filament. The filament acts as a sensor, with its resistance dropping when air flows over it due to convective cooling. This resistance change is amplified by an LM339 operational amplifier and used to vary the brightness of an LED, providing a visual indication of the air flow rate. The circuit also includes voltage regulators to provide stable power and can be used to detect air flow in industrial, medical, or automotive applications.
open circuit and short circuit test on transformerMILAN MANAVAR
This document describes open circuit and short circuit tests performed on transformers. The open circuit test is done to measure iron losses by connecting meters to the primary side with the secondary open. The short circuit test is done to measure copper losses by shorting the secondary and applying a small voltage to the primary side. These tests allow determining key transformer parameters like losses and efficiency without actual loading and are economical and convenient.
This document provides information about transformers, including their components, principles of operation, and applications. It discusses how transformers transfer electrical energy from one circuit to another through electromagnetic induction, changing the voltage and current magnitudes but not the frequency. The key components are the core, primary winding, and secondary winding. Transformers operate based on the principle of mutual induction between the windings. They are used in various applications like power transmission and audio/radio frequencies.
The document discusses the unique role and design requirements of wind turbine step-up (WTSU) transformers. WTSU transformers differ from conventional distribution transformers and generator step-up transformers in several key ways. They experience wide variations in loading from intermittent wind, harmonic loads from electronic controls, must be sized without overload capacity, and must withstand faults while wind turbines remain connected to the grid. As a result, the document argues that WTSU transformers require a uniquely robust design that is tailored to their operating conditions and is not suited for conventional "off the shelf" transformers.
Harnessing wind energy to perform work is not a new concept.
Since the earliest of times, wind power has captured with sails to allow traders, merchants and explorers to ply their trades and discover the world around them.
The first quarter of 2009 has ushered in a new era for the alternate energy market in the US. This has resulted in a visible increase in interest on alternate energy technologies. Most would think the attention to alternate energy has come just in time, especially with the rise in fossil fuel prices, stringent environmental regulations, and significant changes in preferences among consumers.
The definition of the "Smart Grid" is something that is taking shape. Utility professionals concur on some aspects and ideas of what the smart grid should be, but there are still grey areas that, however, promise to become clearer soon.
Pacific Crest padmounted transformers are designed for use in distribution applications as well as for dedicated loads, and are designed for ease of installation and first cost savings.
The United States, like many other countries worldwide, is experiencing a growing concern about the environment. Currently more the domain of activists and environmental organizations, it is only a matter of times before these concerns grip consumers as well - maybe even to the point when they get discerning enough to question the source of their electricity.
- The document discusses the application and coordination of primary fuses.
- It describes how fuse links act as protective devices, protecting equipment from overcurrent and isolating faults. The time-current characteristics of fuse links must be selected to provide coordination between protective devices.
- Transformers and sectionalizing fuses are discussed as common applications. Dual-characteristic fuses like SloFast are described as providing better protection of transformers compared to standard fuses. Coordination between protecting and protected fuses is also explained.
The 7PG21 is a three phase unit differential protection used to detect in zone phase and earth faults. The relay is applied to overhead line and underground cable circuits as well as shorter circuits such as interconnectors.
Relays (and associated CTs) are installed at each end of the protected circuit and connected together with dedicated metallic pilot wires.
The document discusses the design and simulation of an inverter that can convert DC power from renewable energy sources into AC power that can be used by ordinary appliances or added to the electrical grid. It begins by explaining what an inverter is and why the researchers chose to build their own custom inverter rather than modifying a commercial one. It then outlines the design objectives, specifications, basic design choices around switching technologies and circuit topologies, and control algorithms. The document concludes by discussing simulating the inverter design using software and considering practical design issues like sensing output current for control.
The document discusses requirements for selecting interposing relays used in remote control of circuit breakers. It provides guidelines on ensuring interposing relay contacts can make and carry coil currents without needing to interrupt them. The contacts only need to carry current for the tens of milliseconds it takes for the circuit breaker to operate. Typical interposing relays and a control scheme are presented, with notes on matching relay pickup voltages and ensuring long enough signal durations.
transformerdesignandprotection-130408132534-phpapp02.pptThien Phan Bản
The document discusses transformer protection principles and methods. It describes various types of faults that can occur in transformers like ground faults, phase-to-phase faults, and interturn faults. It then covers mechanical protections like Buchholz relays, sudden pressure relays, pressure relief valves, and temperature indicators. Electrical protections discussed include biased differential relays, restricted earth fault relays, and overfluxing protection relays with inverse-time characteristics to match transformer thermal withstand capabilities.
2003 09-08 joeck icefa fuse protection in transformer pole substationRemigiusz Joeck
This document summarizes the use of fuses to protect transformer pole substations in Poland. It discusses how expulsion fuses are commonly used on the medium-voltage side for transformers up to 400 kVA when short-circuit currents do not exceed 3.15 kA. Current-limiting fuses are used for larger transformers or higher short-circuit currents. On the low-voltage side, fuses with a time-current characteristic of gG or gF are typically used. The document also provides guidelines on properly selecting and coordinating fuses on both the MV and LV sides of transformer substations for effective protection against overloads and short-circuits.
The document provides an overview of NEOZED fuse systems, including:
1) NEOZED fuse links that have rated voltages of 400V AC/250V DC, sizes from D01 to D03, and rated currents from 2A to 100A.
2) NEOZED fuse bases that are made of ceramic or molded plastic, available in 1-pole and 3-pole, and sizes D01 and D02 for rail or busbar mounting.
3) NEOZED fuse disconnectors that use a draw-out design for safe changing of fuse links without voltage, are size D01, and can be rail or busbar mounted with a sealable switch.
This document defines and explains the key parameters listed on diode data sheets. It discusses maximum ratings like reverse voltage and forward current, as well as static electrical characteristics like forward voltage. Maximum ratings specify limits to ensure reliable operation, while typical values are provided for forward voltage under different temperature and current conditions. The document aims to help designers properly interpret data sheet specifications when selecting parts for new circuit designs.
The document discusses substations and their components. It defines a substation as an assembly of apparatus that transforms electrical energy from one form to another, such as changing voltage levels. Substations contain step-up transformers to increase voltage for transmission and step-down transformers to decrease voltage for distribution to consumers. The document describes various types of substations and explains their functions. It also provides details about components within substations such as circuit breakers, transformers, buses, isolators and instrument transformers.
The document discusses transformer protection principles, including:
1. Transformer protection aims to limit damage from faults by identifying abnormal operating conditions. Differential, overcurrent, temperature and other protections are used.
2. Protections detect faults, overloads and minimize disconnection time to simplify repair and reduce failure risk.
3. GE Multilin relays provide comprehensive protection including differential, restricted ground fault, overflux and thermal protections in products like the T60 and T35.
Remediation of Old Substations for Arc Flash hazardIJAPEJOURNAL
Arc Flash is much different from the conventional shock hazard in the sense that it doesn’t involve direct contact of human beings with the live or energized part. The arcing energy involves high temperature of up to or beyond 20000K. This paper presents a case study of arc flash hazard analysis carried out in older industrial plant and the technological and work procedure changes that can be incorporated to reduce the incident energy level and thus provide a safer environment for the working personnels in plant.
This document discusses short-circuit calculations and selective coordination for electrical systems. It explains that short-circuit studies are required by the National Electrical Code to properly size overcurrent protection devices and ensure system coordination. The document provides guidance on calculating available short-circuit current values at different points in a system using the point-to-point method, which accounts for sources of fault current and impedances of system components. It also addresses variables that affect fault current values, such as transformer impedance, motor contribution, and utility voltage tolerance.
(1) Five classical types of busbar protection systems are discussed: system protection, frame-earth protection, differential protection, phase comparison protection, and directional blocking protection. System protection and phase comparison protection are only suitable for small substations, while frame-earth and differential protection are discussed in more detail.
(2) Frame-earth protection measures fault current flowing from the switchgear frame to earth. Differential protection compares currents flowing into and out of the busbar and trips if they are not equal.
(3) Modern digital differential algorithms aim to improve filtering, response time, restraint techniques, and transient blocking compared to classical schemes.
This document describes various principles of relay operation used in power systems. It discusses several categories of relays including level detection relays, magnitude comparison relays, differential relays, phase angle comparison relays, distance relays, pilot relays, harmonic content relays, and frequency sensing relays. It also describes some common relay designs such as plunger-type electromechanical relays and their operating characteristics. Relay principles can be based on detecting changes in current, voltage, phase angles, harmonic components, or frequency during fault conditions.
This document discusses sheath voltage limiters (SVLs), which are surge arresters used to protect the outer jacket of underground high voltage cables. SVLs limit the voltage stress across the cable jacket during transient overvoltage events like faults, switching surges and lightning strikes to prevent puncture and moisture ingress. The document provides guidelines for selecting the proper rating for SVLs, including calculating the voltage that could appear on the cable sheath during faults based on cable characteristics, and ensuring the SVL's voltage rating is above this level so it does not conduct during faults. It also discusses using simulations and margins of protection to determine if the SVL can adequately protect the cable jacket from other transient overvoltages.
The document discusses current transformer (CT) selection considerations for protective relays like the GE 489 Generator Management Relay. It covers CT characteristics that impact relay operation, including burden, excitation curves, linear and saturated operation ranges, and response to steady state currents and transient faults. CT selection requires matching CT and relay characteristics, considering factors like relay settings, lead lengths, system impedance, and protection philosophy. The document provides guidelines for selecting CTs that ensure proper relay performance under all operating conditions.
International Journal of Engineering Research and Applications (IJERA) is an open access online peer reviewed international journal that publishes research and review articles in the fields of Computer Science, Neural Networks, Electrical Engineering, Software Engineering, Information Technology, Mechanical Engineering, Chemical Engineering, Plastic Engineering, Food Technology, Textile Engineering, Nano Technology & science, Power Electronics, Electronics & Communication Engineering, Computational mathematics, Image processing, Civil Engineering, Structural Engineering, Environmental Engineering, VLSI Testing & Low Power VLSI Design etc.
Auto Reset on Temporary Fault Otherwise Permanent Trip in Three Phase Transmi...IRJET Journal
This document describes an automatic tripping mechanism for a three-phase power supply system. The system is designed to automatically reset after a brief interruption for temporary faults, but remain tripped for permanent faults. The system uses components like a voltage regulator, 555 timer, operational amplifiers, relays, diodes, resistors, and capacitors. It is designed to detect faults like line-ground, line-line, and three-line faults and help protect power system equipment from damage due to faults.
Multi-power rail FLR configurable for Digital CircuitsIRJET Journal
This document proposes a multi-power rail configurable fast load regulator (FLR) for digital circuits. The FLR uses dual 1.8V and 3.3V power rails to improve power efficiency by 40% compared to a single 3.3V rail, especially at lower output voltages of 1.0V. The architecture is optimized so that 80% of the current comes from the 1.8V rail at 1.0V output, decreasing as the output voltage increases toward 1.5V. Protection transistors are added to prevent latch-up by ensuring only one power rail is active at a time. Simulation results show the schematic and layout of the proposed FLR.
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Pushing the limits of ePRTC: 100ns holdover for 100 daysAdtran
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Report on matched-melt coordination as used for selecting windfarm fuses
1. TR0902: Report on matched-melt coordination as
used for selecting windfarm fuses
By
Dan Gardner,
P.E., R&D Manager
Hi-Tech, Thomas & Betts Corporation
2. TR0902: Report on matched-melt coordination as used for selecting windfarm fuses
WHAT IS MATCH-MELT COORDINATION?
Matched-melt coordination as defined in IEEE C37.48 is a variation of time-current curve
coordination that is used to ensure that the expulsion fuse melts open during any overload or
fault condition. As stated in IEEE C37.48,
The principal advantage of the matched-melt method is that the expulsion fuse will melt open
even if the current limiting fuse does the actual clearing. Because the expulsion fuse opens, the
current-limiting fuse is not likely to have the system’s voltage impressed across it after it has
operated.
The main advantage of this type of coordination is that in most three-phase applications, the
voltage rating of the backup current-limiting fuse need only be equal to the system’s line-to-
neutral voltage as long as the voltage rating of the expulsion fuse is equal to the system’s line-to-
line voltage.
WHAT DOES MATCHED-MELT COORDINATION HAVE TO DO WITH WINDFARM
TRANSFORMER PROTECTION?
Windfarm transformers are predominately 34.5kV and are delta-connected (or ungrounded).
IEEE C37.48 specifies that fuses used to protect ungrounded systems should have a maximum
voltage rating equal to or exceeding the maximum system L-L voltage. The only exception to
this rule allowed by the standard is when matched-melt coordination is used. As stated
previously, when matched-melt coordination requirements are met, L-N rated backup fuses can
often be used.
Until recently, no 38kV oil-submersible backup fuses were available. It was therefore not
possible to provide a L-L rated backup fuse for a 34.5kV delta-connected transformer. Matched-
melt coordination has therefore been used with the L-L rated 34.5kV ABB weak link expulsion
fuses to allow the use of 23kV backup fuses.
WHY IS IT CRITICAL THAT MATCHED-MELT COORDINATION REQUIREMENTS ARE
STRICTLY OBSERVED IN DELTA-CONNECTED WINDFARM APPLICATIONS IF L-N
RATED BACKUP FUSES ARE TO BE USED?
Due to the nature of a windfarm application, a number of conditions exist that are not explicitly
covered in IEEE C37.48 as it focuses on distribution transformer protection. Most importantly, in
a windfarm application, both sides of the transformer are “active”, meaning that a fault can be
fed from either side, the generator on the low voltage side and the collector system on the high
voltage side (this as opposed to a distribution transformer application where the load side of the
transformer is “passive”).
When a fault occurs causing the fusing on the 34.5kV side of the transformer to operate, a brief
period of de-synchronization can occur between the phase voltages on the generator side of the
transformer and the phase voltages on the collector side of the transformer. The phase voltages
can move out of sync until such a time as the generator protection opens, entirely isolating the
transformer. During this period of time, the voltage across the open fuses could be on the
magnitude of twice system L-L voltage.
The long oil gap that results in the open ABB 34.5kV weak link appears to be able to withstand
this voltage until the breaker on the low voltage side of the transformer operates, often sharing
that duty with the open backup fuse. There is not sufficient testing or experience to show that an
L-N rated backup fuse could withstand what could be on the order of three times its rated
voltage alone, even if it did initially interrupt.
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3. TR0902: Report on matched-melt coordination as used for selecting windfarm fuses
WHAT IS REQUIRED TO ACHIEVE MATCH-MELT COORDINATION WITH THE ABB 34.5KV
WEAK LINKS?
In addition to meeting all requirements needed for time-current curve crossover coordination as
specified in IEEE C37.48, there are two other requirements that must be met:
1. The first requirement is that one must ensure that the expulsion fuse melts open any time
the two fuse combination clears an overload or fault. IEEE C37.48 states that
Coordination can be realized as long as the maximum melting I2t of the expulsion fuse does not
exceed approximately twice the minimum melting I2t of the current-limiting fuse.
While the minimum melting I2t for backup fuses is readily available in published literature, the
maximum melt I2t for expulsion fuses is not so readily available. IEEE C37.48 therefore
recommends a method for calculating this value from the minimum melting curves of the
expulsion fuses as stated below
One method of calculation involves first determining the current corresponding to the value of
time representing the fewest whole numbers of quarter-cycles. For many published curves this
might be the current corresponding to three (3) quarter cycles (0.0125 s). Once the current has
been determined from the expulsion fuse’s minimum melting curve, it should be increased by an
appropriate factor to take into account variations resulting from manufacturing tolerances. In
the case of expulsion fuses having silver elements, this factor is 10%. For fuses with elements
made from other materials, this factor is normally 20%. After the current has been corrected to
allow for manufacturing tolerances, the maximum melting I 2t of the expulsion fuse can be
calculated by first squaring this current and then multiplying that value by the time (expressed in
seconds) that was the basis for determining the current.
However, while this method works well for many types of expulsion fuses, it cannot be used to
calculate the maximum melt I2t of the ABB 34.5kV weak link fuses that are used in Windfarm
applications. This is because C37.48 assumes that published curves meet the requirements set
forth in IEEE C37.47 which states that
When publishing time current curves, the maximum melting current shall not exceed the
minimum melting current by more than 20% for any given melting time.
The ABB weak link curves were published well before the present IEEE standards and therefore
do not meet the above requirement as it did not exist. In some cases, the margins on the
published ABB curves are as large as 60%. They also publish an average clearing curve as
opposed to the total clearing curve required by the present standards. Their average clearing
curve must be shifted by 10% to the right in order to model the total clearing curve needed to
perform time-current curve crossover coordination per C37.48. Using the published ABB
minimum melting curves to calculate their maximum melting I2t will result in values that can be
off by a factor of almost two.
Maximum melting I2t values for the ABB weak links must therefore be obtained through other
means. An example of this for the ABB #9 weak link can be seen in Appendix I.
2. The second requirement is one that is specific to applications where match-melt
coordination is used to coordinate fuses used in pad-mounted transformers due to the very
3
4. TR0902: Report on matched-melt coordination as used for selecting windfarm fuses
low maximum interrupting currents of the expulsion fuses in such applications. Specifically,
matched-melt coordination as specified in IEEE C37.48 assumes that the current-limiting
fuses being used will be melting in the first loop of fault current at the maximum interrupting
current of the expulsion fuse.
When this is not the case, additional testing on the L-N rated backup fuses is needed to show
that they can interrupt L-L voltage at currents that cause melting in times longer than 1 loop
down to a current equal to the maximum interrupting current of the expulsion fuse.
It is well-known that two L-N rated current-limiting fuses (one from each phase) will melt
simultaneously and share the interruption duty to interrupt a L-L fault when operating in their
current-limiting mode (i.e. melting during the first loop of fault current); hence the assumption
made in the standard as described in the preceding paragraph. However, at longer melting
times, conditions can occur due to slight differences in fuse tolerances or starting temperatures
that will result in one fuse melting slightly ahead of the other.
When a fuse in one phase melts even slightly ahead of the fuse in another phase, the
resistance that it introduces into the circuit will cause the current to drop significantly, and the
second fuse may not melt in time to share in the interruption. It is therefore imperative that any
L-N rated backup fuse that might be matched-melt coordinated with the ABB weak links is
shown to be capable of interrupting L-L voltage by itself (as a single fuse) from 1200A (the
maximum interrupting current of the ABB 34.5kV expulsion fuses) up to a current that is high
enough to ensure that the fuses from each phase on a L-L fault will always melt together and
share the interruption duty, regardless of the slight variations described above.
WHAT BACKUP FUSES ARE AVAILABLE TODAY THAT MEET BOTH OF THE
REQUIREMENTS DISCUSSED ABOVE FOR THE ABB #8 AND #9 WEAK LINKS?
In addition to the windfarm specific testing described in the second requirement above, any
backup fuse that is to be used should have a published melt I2t that is greater than the values
listed in the table below in order to meet match-melt coordination requirements per IEEE
C37.48.
4
5. TR0902: Report on matched-melt coordination as used for selecting windfarm fuses
T&B Hi-Tech has performed the testing as described in the second requirement above on fuse
ratings that meet match-melt coordination requirements for both the #8 and #9 weak links. The
Hi-Tech HTDS352100 fuse has been tested and match-melt coordinates with the ABB #8 weak
links. The 2xHTSS252100 fuses have been tested and match-melt coordinates with the ABB #9
weak links. Full test reports that show how the fuses were tested are available. A competitor is
now also claiming to have performed the extra testing required on some of their backup fuse
ratings to allow them to be used on windfarm applications. However, some of the fuses they
claim meet match-melt coordination requirements with the ABB #8 and #9 weak links do not
meet the key requirement needed to achieve match-melt coordination as specified by the IEEE
because the competitor used the published ABB curves to calculate the maximum melt I2t’s of
the ABB links. An example of the recommendation that is being made using the #9 ABB weak
link, and why that recommendation is not suitable and does not indeed meet IEEE specified
requirements for match-melt coordination, is shown in Appendix II. The size of the competitor’s
fuse that would be needed to meet match-melt coordination requirements with the #9 weak link
has not had any of the additional testing performed on it and has therefore not been shown to
be suitable for windfarm applications at this time.
5
6. TR0902: Report on matched-melt coordination as used for selecting windfarm fuses
6
7. TR0902: Report on matched-melt coordination as used for selecting windfarm fuses
7