The document discusses improvements to MV pole mounted transformer installations to reduce failures during lightning storms. A Lightning Proof Fuse (LPF) was developed to reduce fuse failures from lightning. A Combi Unit was also developed, consisting of a drop-out fuse and surge arrester in one unit. This ensures both the transformer and fuse are always protected from lightning. Installation of the Combi Unit greatly improves network performance and safety by eliminating the need for staff to work at heights when replacing equipment. Field testing found the Combi Unit reduced transformer failures significantly.
- 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 document provides an overview of different protection systems, including power system protection, lightning protection systems, and train protection systems.
Power system protection aims to isolate faults or overloads to prevent damage and injuries. It uses components like current transformers, voltage transformers, protective relays, circuit breakers and batteries. Coordination ensures protective devices operate in the optimal timed sequence.
Lightning protection systems provide a low impedance path for lightning to ground to reduce structural damage risks. Devices include lightning arresters, rods and detectors.
Train protection systems ensure safe operation in the event of human error. Early inductive systems transmitted data magnetically between tracks and locomotives. Modern cab signalling systems constantly update drivers on train positions and speeds
The document discusses insulation coordination studies for selecting insulation strength consistent with expected overvoltages. It defines insulation coordination and describes understanding insulation stresses and strength. Methods for controlling stresses include surge arresters, pre-insertion resistors, and synchronous closing control. Insulation coordination studies evaluate overvoltages from very fast transients, lightning, switching, and temporary conditions to verify protection of electrical equipment. An example application performs a lightning surge analysis of a 550kV gas-insulated substation to evaluate protective margins of equipment.
This document discusses insulation coordination for electrical systems. It defines insulation coordination as selecting suitable insulation levels for system components and arranging them rationally. The goals of insulation coordination are to ensure insulation can withstand normal and abnormal stresses and efficiently discharge over voltages. It also discusses determining live insulation levels, equipment BIL levels, and selecting lightning arrestors. Various insulation levels for lines and equipment are recommended based on system voltage.
This presentation discusses insulation coordination in power systems. It introduces insulation coordination and its purpose to determine necessary insulation characteristics to withstand normal and over voltages. The presentation covers the basic insulation level (BIL) process, which establishes a common insulation level for all system components. It also describes the insulation coordination process, which involves understanding insulation stresses and strengths, controlling stresses, and designing insulation systems. The presentation concludes that insulation coordination balances equipment reliability and costs by properly matching insulation strength to system stresses.
The document discusses considerations for sizing conductors connecting station class arresters to transformers. It states that the conductor diameter has a negligible effect on the arrester's protection, but the length can impact inductance and protection. The key factors for sizing conductors are mechanical strength to withstand fault currents without failing, limiting corona at high voltages, and minimizing voltage reflections from separation of arrester and bushing. The optimum conductor size is determined by mechanical requirements over electrical considerations.
The document describes a LightningMat EPR Safety Mat, which is a portable mat that can mitigate hazards from earth potential rise (EPR) during lightning strikes or electrical faults. It discusses the mat's unique three-layer design that redistributes voltage gradients across its surface to protect people standing on it. The mat is flexible, lightweight, and can be rolled up for easy transport and installation. It has applications for workers in remote or outdoor environments and anyone near conductive infrastructure.
- 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 document provides an overview of different protection systems, including power system protection, lightning protection systems, and train protection systems.
Power system protection aims to isolate faults or overloads to prevent damage and injuries. It uses components like current transformers, voltage transformers, protective relays, circuit breakers and batteries. Coordination ensures protective devices operate in the optimal timed sequence.
Lightning protection systems provide a low impedance path for lightning to ground to reduce structural damage risks. Devices include lightning arresters, rods and detectors.
Train protection systems ensure safe operation in the event of human error. Early inductive systems transmitted data magnetically between tracks and locomotives. Modern cab signalling systems constantly update drivers on train positions and speeds
The document discusses insulation coordination studies for selecting insulation strength consistent with expected overvoltages. It defines insulation coordination and describes understanding insulation stresses and strength. Methods for controlling stresses include surge arresters, pre-insertion resistors, and synchronous closing control. Insulation coordination studies evaluate overvoltages from very fast transients, lightning, switching, and temporary conditions to verify protection of electrical equipment. An example application performs a lightning surge analysis of a 550kV gas-insulated substation to evaluate protective margins of equipment.
This document discusses insulation coordination for electrical systems. It defines insulation coordination as selecting suitable insulation levels for system components and arranging them rationally. The goals of insulation coordination are to ensure insulation can withstand normal and abnormal stresses and efficiently discharge over voltages. It also discusses determining live insulation levels, equipment BIL levels, and selecting lightning arrestors. Various insulation levels for lines and equipment are recommended based on system voltage.
This presentation discusses insulation coordination in power systems. It introduces insulation coordination and its purpose to determine necessary insulation characteristics to withstand normal and over voltages. The presentation covers the basic insulation level (BIL) process, which establishes a common insulation level for all system components. It also describes the insulation coordination process, which involves understanding insulation stresses and strengths, controlling stresses, and designing insulation systems. The presentation concludes that insulation coordination balances equipment reliability and costs by properly matching insulation strength to system stresses.
The document discusses considerations for sizing conductors connecting station class arresters to transformers. It states that the conductor diameter has a negligible effect on the arrester's protection, but the length can impact inductance and protection. The key factors for sizing conductors are mechanical strength to withstand fault currents without failing, limiting corona at high voltages, and minimizing voltage reflections from separation of arrester and bushing. The optimum conductor size is determined by mechanical requirements over electrical considerations.
The document describes a LightningMat EPR Safety Mat, which is a portable mat that can mitigate hazards from earth potential rise (EPR) during lightning strikes or electrical faults. It discusses the mat's unique three-layer design that redistributes voltage gradients across its surface to protect people standing on it. The mat is flexible, lightweight, and can be rolled up for easy transport and installation. It has applications for workers in remote or outdoor environments and anyone near conductive infrastructure.
Overvoltages can be caused by both external and internal factors in power systems. Switching surges are now the dominant design factor for EHV and UHV systems, while lightning surges are less important. Switching surges are generated by events like energizing lines, load rejection, and fault clearing. They take the form of traveling waves on the lines. Temporary overvoltages can last from cycles to seconds and are caused by events like load rejection, the Ferranti effect, and ground faults. Overvoltages can be controlled by phase-controlled switching, use of resistors, reactors, and draining trapped charges. Surge arresters like zinc oxide varistors protect equipment by conducting current during an overvoltage and limiting
The document discusses earthing arrangements and protection against electric shock. It defines key terms like earthing, protective conductors, and fault conditions. It describes the three common earthing arrangements - TT, TN-S, and TN-C-S systems. For each system, it explains the wiring configuration and how fault currents flow. Protection methods like RCDs and their operation are also covered to prevent electric shock. Diagrams and formulas are provided to calculate touch voltages and ensure safety.
The document discusses rotor earth fault protection for generators. It describes two principles for detecting earth faults: using a 50/60 Hz injected voltage and using a low frequency (1-3 Hz) square wave voltage. The 50/60 Hz method directly measures the earth fault current, while the square wave method measures the voltage difference caused by charging of the rotor capacitance. Settings and logic for protection relays are provided for both methods. Considerations for parallel operation of the two types of protections are also covered.
Post Glover is a leading manufacturer of grounding solutions and dynamic braking resistors. They have over 130 years of combined industrial and utility experience. Their factory in Kentucky integrates computer-aided design and manufacturing with strong engineering capabilities. Their experienced sales and engineering team provides timely support and response. Post Glover designs and manufactures products in accordance with all applicable safety standards. They offer various grounding solutions including neutral grounding resistors and grounding transformers.
This document discusses power system protection settings and provides information on calculating protection settings. It covers the functions of protective relays and equipment protection, the required information for setting calculations such as line parameters and fault studies, and the process of calculating, checking, and implementing protection settings. The goal is to set protections to operate dependably, securely, and selectively during faults while meeting clearance time requirements.
This document discusses electrical protection systems for power stations. It explains the need for protection against faults like overcurrent and earth faults to isolate faulty equipment quickly. Detection of faults is done by measuring changes in current and voltage using transformers and relays. Different types of protection relays and schemes are described to discriminate faults and provide backup protection for transformers, circuits, busbars and generators.
The document summarizes a presentation on lightning insulation coordination studies using DIgSILENT PowerFactory software. It describes modeling transmission line components, surge arresters, tower footing resistance, and stroke current waveforms. A case study is shown applying these models to analyze voltages and currents during a 20kA direct lightning strike on a transmission line. Results are presented for multiple network nodes showing voltages remain below equipment flashover levels.
SEBA KMT MFM5-1 is the universal test instrument for cable sheath testing including prelocation and pinpointing of cable sheath faults - in sheath testing mode SEBA KMT MFM5-1 can detect minute cable sheath insulation damage on low and high voltage cable networks.
SEBA KMT MFM5-1 ensures fast and precise cable sheath fault location - the instrument is menu-driven and fully automatic sheath fault prelocation is accurately achieved by inputting total cable length. SEBA KMT ESG 80-2 can be combined with the MFM5-1 for earth fault location in LV-HV cables.
Cable Sheath Test & Fault Location SEBA KMT MFM5-1 Features : Sheath testing, fault prelocation and pinpointing combined in single unit, sheath testing up to 5kV, time saving prelocation of sheath fault.
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.
This document discusses insulation coordination, which involves selecting insulation levels for electrical system components and arranging them rationally. Proper insulation coordination ensures reliability by minimizing failures from overvoltages while reducing costs. Key aspects covered include determining line and equipment insulation levels, selecting surge arrestors, and the ideal characteristics of protective devices to coordinate insulation withstand. The relationship between insulation, protective device characteristics, and location of surge arrestors is also examined.
Lightning protection for overhead distribution linesGilberto Mejía
This document summarizes techniques for lightning protection of overhead power distribution lines. It discusses the types of lightning overvoltages that can occur on medium voltage (MV) and low voltage (LV) networks from direct strikes and indirect strikes. Direct strikes can cause overvoltages over 2000kV, far exceeding insulation levels and causing flashovers. Indirect strikes have lower but still significant voltages and are more common. The document reviews methods to mitigate these overvoltages, including increasing insulation, using grounded shield wires, and installing surge arresters. Shield wires and arresters are most effective at reducing faults from direct strikes, while all methods help reduce faults from indirect strikes.
This document discusses lightning protection for roof-top photovoltaic (PV) systems. It begins by introducing the issues of energy crisis and using solar energy from PV panels. It then covers lightning phenomena and the need to protect electrical equipment. The document details external and internal lightning protection systems, including air termination systems, down conductors, earth termination systems, and lightning protection zones. It emphasizes the vulnerability of roof-top PV systems and recommends designing lightning protection that isolates the PV panels while still providing a protected location for installation.
During producing, processing, storing and transporting flammable substances (e.g. fuel, alcohol, liquid gas, explosive dusts), potentially explosive atmospheres where no ignition sources may be present to prevent explosion frequently occur in chemical and petrochemical industrial plants. The relevant safety regulations describe the risk for such plants posed by atmospheric discharges (lightning strikes). In this context, it must be observed that there is a risk of re and explosion resulting from direct or indirect lightning discharge since in some cases these plants are widely distributed.
To ensure the required plant availability and safety, a conceptual procedure is required to protect parts of electrical and electronic installations of process plants from lightning cur- rents and surges.
This document provides answers to various electrical engineering questions. It explains that ELCBs cannot work properly if the neutral input is not grounded because it needs the return current path to detect faults. It distinguishes between MCBs and MCCBs based on their current ratings and types of protection. It also describes why earth pins are thicker than other pins in plugs and why delta-star transformers are used for lighting loads.
This document discusses grounding and its importance in electrical systems. It explains that ground provides a path for fault currents, stabilizes electrical signals, and limits voltage rises from transients. A good ground connection is important for safety and proper system operation. It then discusses grounding in AC power systems, how homes in North America are supplied 240V split-phase power from utilities via three wires, and how the electrical service panel distributes this power to circuits while connecting all grounds to earth.
This document provides information on medium voltage HRC fuses. It describes the key features of HRC fuse-links, which have high rupturing capacity and can limit short-circuit currents. The fuse-links are used to protect transformers, capacitor banks, cables, and overhead lines. The document discusses fuse-link and fuse-base types, specifications, applications, selection criteria based on rated voltage and current, installation guidelines, and compliance with various standards.
The document discusses various aspects of power system protection. It describes different types of electrical faults that can occur, such as phase-to-phase short circuits and phase-to-ground faults. The key tasks of a protection system are to protect electrical equipment from unnecessary damage, protect personnel near faults, and enable continued service in unaffected areas. Protection schemes aim to operate abnormally but securely, maintaining normal operation until a fault occurs. Requirements for protection systems include speed, selectivity, sensitivity, reliability and simplicity. The document outlines protection schemes and relay logic for generators, transformers, feeders and busbars.
The document discusses insulation coordination design details for HVDC converter stations. It provides definitions for various impulse withstand levels needed, including switching impulse withstand level (SIWL), lightning impulse withstand level (LIWL), and front of wave (FOW) impulse. It discusses the reasons for these different impulse levels and provides the design criteria. It also summarizes the different types of arresters used on the AC and DC sides of converter stations, providing their ratings and maximum voltages. Coordination is discussed between the AC line and station arresters to ensure adequate margins.
Lightning protection 1 by ambuj mishraAmbuj Mishra
The document discusses lightning protection systems. It begins by defining lightning and explaining the anatomy of a lightning stroke. It then discusses why lightning protection is needed, especially for tall structures, areas with many people, and essential services. The main concepts of protection systems are explained, showing how air terminals intercept lightning and send current to ground electrodes via down conductors. The key components of protection systems - air terminals, down conductors, earth terminals, and earth electrodes - are defined along with their purposes and minimum specifications according to standards. Examples are given of calculating protection needs according to criteria like flash density. Finally, layout and section details of a sample lightning protection installation are presented.
The document provides information about failures of fuses and miniature circuit breakers (MCBs) used in electric locomotives. It discusses the types of fuses used in locomotives, how they protect circuits by melting when current exceeds their rating. When a fuse fails, an indicator shows it needs replacing. MCBs protect against overloads and short circuits electrically or thermally. They are more sensitive and reliable than fuses but also more expensive. The document outlines the construction, working principles, advantages and characteristics of fuses and MCBs used in electric locomotive maintenance.
Based on the experience ABB have gained over the last decades, ABB provides state-of-the-art low-voltage surge protection devices (SPDs), medium and high-voltage surge arresters (SAs) and earthing and lightning protection (ELP) materials to protect
against the impact of direct lightning and transient overvoltages caused by the secondary effects of lightning. Thanks to this wide product-range, ABB offers complete solutions for protection of wind-power installations.
This document discusses overvoltage protection in distribution substations. It describes how lightning is a major cause of overvoltage and can damage electrical equipment if not protected. The Dagon East substation in Myanmar uses DynaVar station class and intermediate lightning arresters rated at 72kV and 10kA to protect its equipment from overvoltage. The arresters help limit transient voltages and protect the substation during lightning strikes and faults, helping to prevent damage and ensure reliable power supply.
Overvoltages can be caused by both external and internal factors in power systems. Switching surges are now the dominant design factor for EHV and UHV systems, while lightning surges are less important. Switching surges are generated by events like energizing lines, load rejection, and fault clearing. They take the form of traveling waves on the lines. Temporary overvoltages can last from cycles to seconds and are caused by events like load rejection, the Ferranti effect, and ground faults. Overvoltages can be controlled by phase-controlled switching, use of resistors, reactors, and draining trapped charges. Surge arresters like zinc oxide varistors protect equipment by conducting current during an overvoltage and limiting
The document discusses earthing arrangements and protection against electric shock. It defines key terms like earthing, protective conductors, and fault conditions. It describes the three common earthing arrangements - TT, TN-S, and TN-C-S systems. For each system, it explains the wiring configuration and how fault currents flow. Protection methods like RCDs and their operation are also covered to prevent electric shock. Diagrams and formulas are provided to calculate touch voltages and ensure safety.
The document discusses rotor earth fault protection for generators. It describes two principles for detecting earth faults: using a 50/60 Hz injected voltage and using a low frequency (1-3 Hz) square wave voltage. The 50/60 Hz method directly measures the earth fault current, while the square wave method measures the voltage difference caused by charging of the rotor capacitance. Settings and logic for protection relays are provided for both methods. Considerations for parallel operation of the two types of protections are also covered.
Post Glover is a leading manufacturer of grounding solutions and dynamic braking resistors. They have over 130 years of combined industrial and utility experience. Their factory in Kentucky integrates computer-aided design and manufacturing with strong engineering capabilities. Their experienced sales and engineering team provides timely support and response. Post Glover designs and manufactures products in accordance with all applicable safety standards. They offer various grounding solutions including neutral grounding resistors and grounding transformers.
This document discusses power system protection settings and provides information on calculating protection settings. It covers the functions of protective relays and equipment protection, the required information for setting calculations such as line parameters and fault studies, and the process of calculating, checking, and implementing protection settings. The goal is to set protections to operate dependably, securely, and selectively during faults while meeting clearance time requirements.
This document discusses electrical protection systems for power stations. It explains the need for protection against faults like overcurrent and earth faults to isolate faulty equipment quickly. Detection of faults is done by measuring changes in current and voltage using transformers and relays. Different types of protection relays and schemes are described to discriminate faults and provide backup protection for transformers, circuits, busbars and generators.
The document summarizes a presentation on lightning insulation coordination studies using DIgSILENT PowerFactory software. It describes modeling transmission line components, surge arresters, tower footing resistance, and stroke current waveforms. A case study is shown applying these models to analyze voltages and currents during a 20kA direct lightning strike on a transmission line. Results are presented for multiple network nodes showing voltages remain below equipment flashover levels.
SEBA KMT MFM5-1 is the universal test instrument for cable sheath testing including prelocation and pinpointing of cable sheath faults - in sheath testing mode SEBA KMT MFM5-1 can detect minute cable sheath insulation damage on low and high voltage cable networks.
SEBA KMT MFM5-1 ensures fast and precise cable sheath fault location - the instrument is menu-driven and fully automatic sheath fault prelocation is accurately achieved by inputting total cable length. SEBA KMT ESG 80-2 can be combined with the MFM5-1 for earth fault location in LV-HV cables.
Cable Sheath Test & Fault Location SEBA KMT MFM5-1 Features : Sheath testing, fault prelocation and pinpointing combined in single unit, sheath testing up to 5kV, time saving prelocation of sheath fault.
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.
This document discusses insulation coordination, which involves selecting insulation levels for electrical system components and arranging them rationally. Proper insulation coordination ensures reliability by minimizing failures from overvoltages while reducing costs. Key aspects covered include determining line and equipment insulation levels, selecting surge arrestors, and the ideal characteristics of protective devices to coordinate insulation withstand. The relationship between insulation, protective device characteristics, and location of surge arrestors is also examined.
Lightning protection for overhead distribution linesGilberto Mejía
This document summarizes techniques for lightning protection of overhead power distribution lines. It discusses the types of lightning overvoltages that can occur on medium voltage (MV) and low voltage (LV) networks from direct strikes and indirect strikes. Direct strikes can cause overvoltages over 2000kV, far exceeding insulation levels and causing flashovers. Indirect strikes have lower but still significant voltages and are more common. The document reviews methods to mitigate these overvoltages, including increasing insulation, using grounded shield wires, and installing surge arresters. Shield wires and arresters are most effective at reducing faults from direct strikes, while all methods help reduce faults from indirect strikes.
This document discusses lightning protection for roof-top photovoltaic (PV) systems. It begins by introducing the issues of energy crisis and using solar energy from PV panels. It then covers lightning phenomena and the need to protect electrical equipment. The document details external and internal lightning protection systems, including air termination systems, down conductors, earth termination systems, and lightning protection zones. It emphasizes the vulnerability of roof-top PV systems and recommends designing lightning protection that isolates the PV panels while still providing a protected location for installation.
During producing, processing, storing and transporting flammable substances (e.g. fuel, alcohol, liquid gas, explosive dusts), potentially explosive atmospheres where no ignition sources may be present to prevent explosion frequently occur in chemical and petrochemical industrial plants. The relevant safety regulations describe the risk for such plants posed by atmospheric discharges (lightning strikes). In this context, it must be observed that there is a risk of re and explosion resulting from direct or indirect lightning discharge since in some cases these plants are widely distributed.
To ensure the required plant availability and safety, a conceptual procedure is required to protect parts of electrical and electronic installations of process plants from lightning cur- rents and surges.
This document provides answers to various electrical engineering questions. It explains that ELCBs cannot work properly if the neutral input is not grounded because it needs the return current path to detect faults. It distinguishes between MCBs and MCCBs based on their current ratings and types of protection. It also describes why earth pins are thicker than other pins in plugs and why delta-star transformers are used for lighting loads.
This document discusses grounding and its importance in electrical systems. It explains that ground provides a path for fault currents, stabilizes electrical signals, and limits voltage rises from transients. A good ground connection is important for safety and proper system operation. It then discusses grounding in AC power systems, how homes in North America are supplied 240V split-phase power from utilities via three wires, and how the electrical service panel distributes this power to circuits while connecting all grounds to earth.
This document provides information on medium voltage HRC fuses. It describes the key features of HRC fuse-links, which have high rupturing capacity and can limit short-circuit currents. The fuse-links are used to protect transformers, capacitor banks, cables, and overhead lines. The document discusses fuse-link and fuse-base types, specifications, applications, selection criteria based on rated voltage and current, installation guidelines, and compliance with various standards.
The document discusses various aspects of power system protection. It describes different types of electrical faults that can occur, such as phase-to-phase short circuits and phase-to-ground faults. The key tasks of a protection system are to protect electrical equipment from unnecessary damage, protect personnel near faults, and enable continued service in unaffected areas. Protection schemes aim to operate abnormally but securely, maintaining normal operation until a fault occurs. Requirements for protection systems include speed, selectivity, sensitivity, reliability and simplicity. The document outlines protection schemes and relay logic for generators, transformers, feeders and busbars.
The document discusses insulation coordination design details for HVDC converter stations. It provides definitions for various impulse withstand levels needed, including switching impulse withstand level (SIWL), lightning impulse withstand level (LIWL), and front of wave (FOW) impulse. It discusses the reasons for these different impulse levels and provides the design criteria. It also summarizes the different types of arresters used on the AC and DC sides of converter stations, providing their ratings and maximum voltages. Coordination is discussed between the AC line and station arresters to ensure adequate margins.
Lightning protection 1 by ambuj mishraAmbuj Mishra
The document discusses lightning protection systems. It begins by defining lightning and explaining the anatomy of a lightning stroke. It then discusses why lightning protection is needed, especially for tall structures, areas with many people, and essential services. The main concepts of protection systems are explained, showing how air terminals intercept lightning and send current to ground electrodes via down conductors. The key components of protection systems - air terminals, down conductors, earth terminals, and earth electrodes - are defined along with their purposes and minimum specifications according to standards. Examples are given of calculating protection needs according to criteria like flash density. Finally, layout and section details of a sample lightning protection installation are presented.
The document provides information about failures of fuses and miniature circuit breakers (MCBs) used in electric locomotives. It discusses the types of fuses used in locomotives, how they protect circuits by melting when current exceeds their rating. When a fuse fails, an indicator shows it needs replacing. MCBs protect against overloads and short circuits electrically or thermally. They are more sensitive and reliable than fuses but also more expensive. The document outlines the construction, working principles, advantages and characteristics of fuses and MCBs used in electric locomotive maintenance.
Based on the experience ABB have gained over the last decades, ABB provides state-of-the-art low-voltage surge protection devices (SPDs), medium and high-voltage surge arresters (SAs) and earthing and lightning protection (ELP) materials to protect
against the impact of direct lightning and transient overvoltages caused by the secondary effects of lightning. Thanks to this wide product-range, ABB offers complete solutions for protection of wind-power installations.
This document discusses overvoltage protection in distribution substations. It describes how lightning is a major cause of overvoltage and can damage electrical equipment if not protected. The Dagon East substation in Myanmar uses DynaVar station class and intermediate lightning arresters rated at 72kV and 10kA to protect its equipment from overvoltage. The arresters help limit transient voltages and protect the substation during lightning strikes and faults, helping to prevent damage and ensure reliable power supply.
Hakel Ltd. is a major producer of surge protection devices in Europe since 1994. It obtained ISO 9001 certification in 1997. Surge protection devices help protect sensitive electronics from electromagnetic interference and overvoltage damage, which can cause equipment failure and financial losses. Hakel produces surge protection devices that can be applied across industries to help protect power systems. It works to develop new technologies and passes knowledge to students. Hakel leads the Czech market and exports worldwide, helping partners develop their businesses. Continual investment helps Hakel achieve high standards and technical solutions.
COMPENSATION OF FAULT RESISTANCE IN DISTANCE RELAY FOR LONG TRANSMISSION LINEIRJET Journal
This document discusses distance protection for long transmission lines and the impact of fault resistance. It begins with an introduction to distance relaying and the issues caused by fault resistance. It then discusses the objectives of analyzing how fault resistance affects protection at different fault distances. The document proposes a new algorithm to estimate fault location and resistance using voltage and current measurements from two terminals. The algorithm compensates for fault resistance in mho-type distance relays by measuring apparent impedance and subtracting the estimated fault resistance. This improves the accuracy of distance protection for faults with resistance on long transmission lines.
1. The document discusses power quality issues in smart grids, including various types of disturbances like voltage sags, transients, and harmonics. It defines several harmonic indices used to measure power quality.
2. Key power quality issues with smart grids are discussed, such as sustained interruptions, voltage regulation challenges, and harmonics from distributed generation sources. Operating conflicts from utility protection requirements, reclosing, interference with relaying, and other issues are also summarized.
3. Various power quality problems that can arise from interactions between distributed generation systems and the grid are described at a high level, including issues related to fault clearing, reclosing, voltage regulation, harmonics, islanding, ferroresonance, and sh
This document discusses methods for protecting water and wastewater treatment plants from lightning strikes and electrical surges. It identifies areas at high risk for lightning strikes, such as pump lift stations and radio antennas. Traditional surge protection methods using MOVs and SADs can be overwhelmed by lightning strikes. Newer triggered arc gap technology provides better protection against high-energy lightning strikes by diverting surge currents to ground. The document describes how triggered arc gaps and additional surge protectors were installed to protect a water treatment plant in Florida that experienced frequent lightning damage.
This document provides information on Cooper Bussmann's medium voltage fuse links, including DIN fuse links. It discusses features and benefits, provides a guide for selection of DIN fuse links, and lists specifications for various DIN fuse link product lines ranging from 3.6kV to 24kV. Key information covered includes voltage ratings, current ratings, body diameters and lengths, striker types, and intended applications.
This document provides information on fuses and circuit breakers used in electrical systems. It discusses the purpose of fuses and circuit breakers as overcurrent protection devices that open a circuit when too much current flows. The key components and operating principles of fuses and various types of circuit breakers like thermal, magnetic, and thermomagnetic are described. Characteristics such as rated current, breaking capacity, and time-current curves are also covered.
Behavioral studies of surge protection componentsjournalBEEI
In our daily life, almost all the items we used, being a computer, television, lift or vehicle we drive consist of some kind of electrical or electronics component inside. The operation of these devices could be severely affected by lightning activity or electrical switching events, as there are more than 2000 thunderstorms in progress at any time resulting in 100 lightning flashes to ground per second. In practice, any device using electricity will subject to surge damages induced from the lightning or switching of heavy load. Surge protection device (SPD) is added at the power distribution panel and critical process loop to prevent damage subsequently cause plant shutdown. There are many questions raised on the SPD. How can this small device protect the equipment from large energy release by the lightning? What is inside the device? How does it work? This paper provides comprehensive detail in revealing the science and engineering behind the SPD, its individual component characteristic and how does it work. The technical information presented is limited to surge protection on equipment; surge protection for building structure will not be discussed here.
Modeling and analysis of power transformers under ferroresonance phenomenonGilberto Mejía
The document discusses modeling a Fernandez surge arrester on a 132kV transmission line using ATP simulation software. It first provides background on lightning, surge arresters, and issues lightning can cause for power systems. It then discusses different surge arrester models including the Fernandez model, and describes modeling the transmission line, tower, and surge arrester in ATP. Simulation results show the output waveform of lightning surge on the line with and without a surge arrester, comparing the standard and Fernandez models. The Fernandez model better represented the surge arrester's dynamic performance during fast lightning events.
Surge protection can improve reliability, availability, and return on assets (ROA) for process plants. Surges are a leading cause of up to 30% of premature electronics failures. While techniques like lightning protection, bonding, and UPS systems help mitigate surges, they do not eliminate the risk. Strategically applying surge protection, especially for critical assets or those at high risk, can directly reduce failures and increase availability. This improves ROA by minimizing downtime and maintenance costs. Prioritizing protection based on asset impact and risk exposure maximizes the financial benefits of surge protection.
The International Journal of Engineering & Science is aimed at providing a platform for researchers, engineers, scientists, or educators to publish their original research results, to exchange new ideas, to disseminate information in innovative designs, engineering experiences and technological skills. It is also the Journal's objective to promote engineering and technology education. All papers submitted to the Journal will be blind peer-reviewed. Only original articles will be published.
The papers for publication in The International Journal of Engineering& Science are selected through rigorous peer reviews to ensure originality, timeliness, relevance, and readability.
1. A substation transforms voltage from high to low or vice versa and performs important functions between the generating station and consumer. Substations may be owned by utilities or large industrial customers.
2. The document discusses types of substations like distribution substations and provides details about components within a substation like incoming transmission lines, lightning arresters, isolators, and earthing rods. It includes diagrams of a single line diagram and lightning arrester.
3. Details are provided about distribution substations, including their role in transferring power from transmission to distribution systems at lower voltages. Components within distribution substations like transformers, feeders, and voltage regulation equipment are also summarized.
Performance of quadrilateral relay on EHV transmission line protection during...IDES Editor
Distance relays have many characteristics
such as Impedance, lenticular, Offset Mho, Mho and
Quadrilateral characteristics. Quadrilateral
characteristics provide highly suitable protection for
Transmission line as compared to other characteristics.
Quadrilateral relay provides flexible protection during
high fault resistance of ground and phase faults. This is
advantageous for protection of phase-to-earth faults on
short lines, lines without earth wires, non-effectively
earthed systems and feeders with extremely high tower
footing resistance. This also provides fault impedance
coverage for both phase to phase and phase to ground
faults without effecting load encroachment. I explained
factors impacting performance of Quadrilateral relay
focusing on accuracy and speed of operation. In this
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Similar to CN 203 - Lightning and Power Frequency Performance of MV Pole Mounted Transformers (20)
CN 203 - Lightning and Power Frequency Performance of MV Pole Mounted Transformers
1. 1
Lightning and Power Frequency Performance of MV Pole Mounted Transformers
M. DU PREEZ W.J.D. VAN SCHALKWYK
Eskom Holdings SOC Ltd Eskom Holdings SOC Ltd
South Africa South Africa
SUMMARY
During lightning storms a large amount of transformers, drop-out fuses and surge arresters fail which
result in extensive unplanned outages. Properly grading MV drop-out fuses with upstream feeder
protection, to ensure correct protection operation during both lightning and power frequency faults, is
a great challenge and for this reason nuisance fusing during storms or incorrect protection operation
during system faults occur frequently. Numerous MV pole mounted transformers fail during lightning
conditions. Blown surge arresters are not always replaced promptly and the pole mounted transformer
are unprotected against lightning for that time. Changing distribution surge arresters or pole mounted
transformers poses safety risks to operators where they are required to work at heights and in close
proximity to high voltages.
A MV pole mounted transformer installation consists of a combination of fuses, surge arresters and a
transformer. In a standard installation the surge arresters protect the transformer against lightning and
the fuses open and isolate a faulty transformer installation from the network.
The Lightning Proof Fuse (LPF) was developed, constructed, tested and implemented at several test
sites. The installation of LPFs eliminates nuisance fusing on MV feeders caused by lightning and still
allows sufficient protection grading. A detailed study was done to determine the optimum placement
and configuration of the equipment at a transformer installation to ensure an improvement in
performance. A strong emphasis was placed on the use of technology to enforce operator discipline. A
Combi unit, consisting of a drop-out fuse and a surge arrester, was developed to resolve the lightning
surge challenges around MV pole mounted transformers installations. The unit also addresses and
resolves the lack of discipline of operational staff. The Combi unit was constructed in such a way that
both the MV pole mounted transformer and drop-out fuses are always protected against lightning by
the surge arresters. The Combi unit also solves the challenge of grading fuses for both lightning and
power frequency faults. Due to the configuration and operation of the Combi unit all operating is done
from ground level with an insulated operating stick eliminating the risks of falling from heights and
inadvertent electrical contact. The installation of Combi units at problematic pole mounted transformer
installations does not only improve network performance and the safety of operating staff, but also
bring about operational cost saving.
KEYWORDS
Combi unit, lightning, drop-out surge arrester, drop-out expulsion fuse, pole-mounted transformer.
7th SOUTHERN AFRICA REGIONAL CONFERENCE
Somerset West, October 2013
2. 2
1. INTRODUCTION
During lightning storms a large amount of transformers, drop-out fuses and surge arresters fail which
result in extensive unplanned outages. It is a great challenge to properly grade MV drop-out fuses with
upstream feeder protection to ensure correct protection operation during lightning and power
frequency faults and for this reason nuisance fusing during storms or incorrect protection operation
during system faults occur frequently. Numerous MV pole mounted transformers fail during lightning
conditions. Blown surge arresters are not always replaced promptly and the pole mounted transformer
will be unprotected from lighting for that time. Changing distribution surge arresters or pole mounted
transformers poses safety risks to operators where they are require to work at heights and in close
proximity to high voltages.
A Lightning Proof Fuse (LPF) was developed to reduce fuse failures due to lightning. A Combi Unit
was developed to resolve the lightning surge challenges around MV pole mounted transformers
installations. The Combi unit ensures that both MV pole mounted transformer and drop-out fuses are
always protected against lightning and solves the challenge of grading fuses for both lightning and
power frequency faults. All operating is done from ground level, eliminating the risks of falling from
heights and inadvertent electrical contact. The installation of Combi units at lightning problematic pole
mounted transformer installations improves network performance and greatly reduces operational
costs.
2. EQUIPMENT FAILURES
Annually many thousands of MV drop-out expulsion fuses and MV pole-mounted transformers in the
old North Western Region are lost particularly during lightning conditions. Table I gives an indication
of the annual amount of failures. If the labour, material and transport cost to replace a pole-mounted
transformer are taken into account (estimated average of R40 000), it is not difficult to see the large
financial implications as well as the negative impact on customer satisfaction. Whereas the average
once off installation cost of a Combi unit 3 phase set is R28 000 and the installation cost of a Lighting
Proof Fuses 3 phase set is R3 000.
Table I Average MV equipment failures per year
Average failures per year Total amount Due to lightning
MV Fuses 16 502 12 789
MV/LV Pole Mounted Transformers 1212 939
3. FUSE OPERATIONS AT LIGHTNING FREQUENCIES
It is a challenge to avoid nuisance fusing on rural feeders caused by lightning impulses while also
making proper 50Hz protection grading possible. In order to minimize nuisance fusing, Field Services
inserted 20A fuses in many pole mount installations. However when a fuse is rated too high it causes
the Sensitive Earth Fault (SEF) protection of the upstream breaker to operate before the fuse blows,
resulting in a line outage.
In some cases where 20 A fuses were installed, only a single fuse operated (the one on the faulted
phase). The other two fuses fed into the fault through the transformer windings, tripping the breaker
on SEF before the fuses blew. It is evident from Table II below that when grading fuses higher (to
limit nuisance fusing due to lightning) results in more breaker operations.
Table II Amount of breaker operations that occurred when transformers with different fuse ratings failed.
Area Fuse sizes used Number of breaker T&L/O operations Number of transformer faults
1 20 A 11 11
3. 3
2 20 A 3 3
3 20 A 8 8
4 8 A 1 18
5 8 & 20 A 12 61
6 20 & 8 A 28 65
It is relatively easy to grade fuses to operate correctly for power frequency faults, however fuses are
also sensitive for high lightning currents. Normally lightning consists of a first stroke followed by
several subsequent strokes as it can be seen in Figure 1. The illustration shows that lightning consists
of three major components namely an amplitude component, the rate at which the current rises and an
energy component that exists due to the DC current found within a lightning flash. The total surface
area underneath the wave form represents the energy that needs to be dissipated by the fuse and surge
arresters on the line.
Figure 1 Three basic components found in a lightning flash [1]
The combination of all of the above given factors contributes to the reason why MV drop-out
expulsion fuses blow for lightning impulses. In practice this means that since lightning flashes are of
very short duration and consists of high peak values with the possibility of a DC component, the
maximum RMS current handling capability of the fuse is reached almost instantaneously, resulting in
a blown fuse (this is mainly due to the energy dissipation in the fuse).
However, this problem can be avoided by the installation of a Lightning Proof Fuse where passive
components are introduced into the circuit or by the installation of a Combi Unit where the fuse is
protected against lightning by the surge arrester.
4. LIGHTNING PROOF FUSE (LPF)
4.1 Circuit Configuration and Parameters
By introducing a spark gap in parallel with a MV drop-out expulsion fuse (which is in series with an
inductor), with the inductor acting as a low impedance path at 50 Hz and as a high impedance device
at lightning frequencies it was found that the arising problems due to lightning frequencies can be
avoided with great success. Figure 2 illustrates the arrangement of the circuit components found in the
fuse and figure 3 shows the operation of the Lightning Proof Fuse.
4. 4
Figure 2 Circuit configuration using a Lightning Proof Fuse
During normal 50 Hz operation the inductor must act as a low impedance path with low over all
energy dissipation. The impedance of the inductor at power frequency is given by:
cL LfX ⋅⋅⋅= π2 (1)
Where:
XL = Power frequency impedance.
f = Power frequency.
Lc = Inductance.
Figure 3 Illustration of the Lightning Proof Fuse operation
This will ensure that the fuse will work correctly for normal over current situations. However, from
equation 1 it can be deduced that the impedance of the circuit will be high for lightning frequencies
resulting in the current attempting to find an alternative conducting path. The maximum volt drop
across the inductor is 75 kV at lightning frequencies and 0.15 V (load current = 5 A) at 50 Hz. The
5. 5
power frequency will pass through the inductor and the fuse while the lightning impulses will flash
over the spark gap, bypassing the fuse element.
4.2 Impulse Test Results
All current impulse tests have been performed at NETFA using 8/20 µs current impulses. The 8/20 µs
current impulse test was done to determine the breakdown currents of the 3 A and 5 A fuses. The 3 A
fuse lasted for 5 tests in succession (without blowing on the last test) with current varying from 20 kA
to 70 kA.
4.3 Advantages
• The advantage of the Lightning Proof Fuse is that it eliminates nuisance fusing on MV feeders
caused by lightning and still allows sufficient protection grading.
• Standard Eskom fuses are used and the LPF fits in a standard fuse holder.
• The LPF saves overtime, man hours and transport costs.
• It minimizes supply loss, voltages unbalance and subsequent equipment damage (pumps,
electronics, and fridges) to customers.
4.4 Disadvantages
• The disadvantage of the LPF is that it does not protect the pole mounted transformer from
lightning.
• Secondly, whenever the fuse blows for a 50 Hz fault at the transformer, a standing back flash-over
will occur across the spark gap while the fuse is falling open. The arc will be cleared by the
upstream breaker. The breaker will auto reclose in about 3s and the faulty transformer is isolated
from the network.
• The LPF is more costly than a standard fuse.
• The LPF cannot be used as a line fuse (coil heats up for load current greater than 15 A).
5. THE COMBI UNIT
The Combi unit consists of a post insulator in the middle with a drop-out type surge arrester on the one
side and a drop-out expulsion fuse on the other side, see Figure 4.
Figure 4 Combi unit consisting of a drop-out expulsion fuse and drop-out surge arrester.
5.1 Development and Operation of the Combi unit
The Combi Unit was primarily developed to minimize the MV drop-out expulsion fuse and MV pole-
mounted transformer failures during lightning activities.
6. 6
In the standard configuration, the MV fuses are exposed to lightning as it is installed line side of the
surge arrester. The surge arrester only protecting the MV transformer as illustrated in Figure 5 (A)
Therefore an alternative configuration was proposed where the surge arrester is connected across the
fuse and transformer to provide lightning protection to both, as can be seen in Figure 5 (B).
Figure 5 (A) Standard pole mounted transformer configuration and (B) Combi unit configuration
The Combi Unit was developed to implement the proposed configuration. Should the fuse blow, only
the fuse will fall open while the arrester stays closed. In the case where the surge arrester GLD
(ground lead disconnect) operates, both the fuse holder (fuse element still healthy) and the surge
arrester fall open. Figure 6 illustrates the operation of the Combi unit.
Figure 6 Illustration of the operation of the Combi unit
5.2 Compliance to Distribution Standard
The Combi unit complies with the DSP 34-1962: Distribution Specification – Part 4: Specification for
a combined cut-out fuse and drop-out surge arrester unit.
5.3 Combi unit Calculations
It can be seen in Figure 7 that the potential difference (voltage drop) across the transformer in the
standard configuration will be 122kV when lightning (34kA 1.2/50µs) terminates on top of the
7. 7
transformer pole. When Combi units are installed 1.5m above the transformer, the surge arresters are
move further and the potential difference across the transformer increases to 137kV, which is still well
below the transformer BIL of 150kV, see Figure 8.
When lightning terminates on the line close to the installation, the voltage across the transformer in the
Combi configuration will be at most 10kV more than for the standard configuration.
Figure 7 Voltage drop calculations of standard configuration
Figure 8 Voltage drop calculations of Combi configuration
8. 8
5.4 Case study
A transformer where a Combi unit set was installed failed on 4 Mar 2011 at 19:07. FALLS (Fault
Analysis and Lightning Location System) was used to locate the lighting strokes that terminated near
the transformer installation and if was found that a 14 kA subsequent lighting stroke (indicated in the
Figure 9 by a red filled ellipse) was responsible for the transformer failure.
Figure 9 Transformer installation and lightning study results
After site inspection it was found that the Combi unit was mounted about 3.5m above the transformer
tank and it resulted in a potential difference (calculated at 206kV) between the transformer windings
and tank (greater than the transformer’s 150kV BIL) when the lightning stroke terminated at the
installation.
5.5 Operating and safety
The only challenge so far was the weight of the surge arrester when a petite operator needs to pick it
up from ground level with a fully extended link stick. However, should the operator uses the correct
method (use the telescopic function of the link stick) the installation of the drop out arrester should not
be more challenging than the installation of a MV drop-out expulsion fuse.
To minimize the risk of falling objects, a tool was developed to replace drop-out surge arresters and
drop-out fuses from ground level using a link stick. Figure 10 shows the insertion tool.
Transformer
RVZ573-13
Lightning strokes
(90% Probability
ellipse)
9. 9
Figure 10 The insertion tool to replace drop out surge arresters and fuses
5.6 Advantages
Using the Combi unit, the following advantages can be expected:
• Replacing drop-out fuses and surge arresters from ground level.
− No slip and fall from step ladder
− No risk of electric contact
• Both the transformer and fuses are protected against lightning.
• No nuisance fusing occurs due to lightning.
• A maximum size of 15A fuses are used in the Combi units to ensure correct protection grading.
• The transformer is always protected against lightning.
• A faulty fuse or surge arrester will fall open and is easily noticeable.
• The Combi unit can be used as an isolation point.
• Standard Eskom fuse and fuse holder is used.
• The Combi unit surge arrester has the same dimension as a drop-out line arrester.
• No outage booking is necessary for the replacement of a fuse or surge arrester.
• The replacement time of a Combi unit surge arrester is much faster than replacing in a surge
arrester in the standard installation.
5.7 Disadvantages
• Cost of installation: it costs more to install a Combi unit than a normal fuse and surge arrester
arrangement.
• Should the surge arrester fail, the customer is without supply. A new surge arrester should
therefore be installed as soon as possible.
• In the Combi configuration the surge arrester is further away from the transformer, resulting in a
137kV impulse level instead of a 122kV potential difference across the transformer. However the
transformer should be insulated at 150kV.
5.8 Performance of the Combi Unit
A total of 1064 pole mount installation were fitted with Combi units over the past 6 years. At all these
installations at least one transformer failure occurred annually. After the installation of Combi units
only 6 transformers were recorded to have failed in the last 6 years, instead of an expected 3000
transformer failures in 6 years’ time. Transformer installations where Combi units are installed can be
seen in Figure 11.
10. 10
Single pole arrangement Double pole arrangementSingle pole arrangement Double pole arrangement
Figure 11 Combi unit installations
5.9 Lessons learned
The 6 installations where the transformer failures occurred were visited and the findings are as follow:
• Three installations had neither neutral arresters nor any connection between the 400V neutral and
earth, leaving the transformer without proper lightning protection.
• One installation was hit by a lightning flash consisting of 18 strokes. All the surge arresters failed
but in the process the transformer was damaged.
• One transformer failed shortly after installation with no lightning in the vicinity – failure not
lightning related.
• Incorrect installation – Combi unit mounted too high above transformer tank. The earth lead was
3.5 m instead of 1 m as indicated in the specification [2].
5.10 Recommendations based on Findings
Combi units should be installed at lightning problematic pole mounted transformer installations to
minimize equipment failures (fuses and transformers), improve network performance and bring about
large operational cost saving. Proper protection grading is achieved and nuisance fusing is eliminated.
Safety: All operating is done from ground level making operating safer and easier. It can be
considered to install Combi units at all transformer installations due to the safety features.
6. BIBLIOGRAPHY
[1] C T Gaunt, A C Britten and H J Geldenhuys, “Insulation co-ordination of unshielded distribution
lines from 1 kV to 36 kV”, SAIEE, pp. 4.
[2] Specification for a combined cut-out fuse and drop-out surge arrester unit, Distribution
Specification DSP 34-1962 Part 4, Mar. 2009.