This document discusses issues that can arise when pipelines and HVAC power lines are located near each other in the same right of way. It describes three main types of interference: electrostatic coupling causing nuisance voltages, conductive coupling producing high fault currents, and inductive coupling generating steady induced AC voltages. Mitigation often involves installing grounding devices to discharge currents and reduce voltages. Modeling of interference is complex, while field testing and risk assessments can also provide useful information for evaluating corrosion and safety risks from alternating currents.
A slide presentation from Rob Shoaf delivered at the Feb. 9, 2011 Gas/Electric Partnership Conference XIX in Cypress, TX. The presentation dealt with the phenomenon of AC electricity running through high voltage lines potentially corroding nearby underground pipelines--and how to mitigate potential problems.
The document discusses issues related to AC corrosion on pipelines located near high-voltage power lines. It provides background on how AC current can be induced in pipelines and details signs of AC corrosion observed in inspections. Thresholds of AC current density are discussed as indicators of potential corrosion risk. Methods for mitigating AC safety hazards and corrosion are described, including installing linear drain systems and deep point drains to divert current from the pipeline. Case studies show modeling and mitigation installation reducing pipeline voltages and current densities to safe levels.
Development of Over-Line Survey Systems for Monitoring Pipelines v1.0 - uploa...David Simmonds
1) Researchers developed an over-line survey system to measure AC voltage and current density on pipelines to identify areas at risk of AC-induced corrosion.
2) Field trials showed that readings from a standard copper wire underestimated actual AC current density by up to 60% due to inductive effects.
3) Models were created to calculate the true AC current density based on measurements and inductance values, resulting in estimates within 10% of actual values.
A substation directs the flow of power through the electric system, protects components from faults, and interconnects transmission lines. It requires careful planning and design to achieve reliability, flexibility, and minimize costs while satisfying electric system requirements. Key elements of substation design include bus configurations, equipment layout and spacing, foundations, protective relaying, surge protection, and environmental considerations. Proper substation design is essential for reliable electric system operation.
The topic mainly deals about different methods of high power Underground transmission systems currently implemented across the world as well as about the modern GIL systems.
It also explain about the advantages, construction and features of GIL (Gas Insulated Transmission Lines) by highlighting its future scope as well.
Europacable is an association of European cable manufacturers that promotes the use of XLPE cables for electricity transmission. They believe XLPE cables are a reliable and innovative technology that have manageable environmental impacts and comparable life-cycle costs to overhead lines. Partial undergrounding using XLPE cables can facilitate grid extension by addressing local concerns and enable the integration of renewable energy sources into Europe's future energy mix.
As the AIS (Air-Insulated Substation) is having more limitations, More and more people are going for the Gas-Insulated Substation which is environment friendly as well.
In these presentation, We discussed about theoritical and technological advancement and advantages related to GIS as compared to other substations.
We discussed different parts of the GIS as well as their operations and advantages.
By going through this presentation, you will have idea regarding comparative advantages and disadvantages of both substations.
This document discusses grounding and bonding testing procedures. It begins with an overview of the key steps: 1) performing an earth (soil) resistivity test, 2) installing the grounding system, and 3) testing the installed system. It then covers details of soil resistivity testing including how to measure resistivity and factors that affect resistivity. The document reviews components of a grounding system including electrodes, conductors, bars and connection methods. It provides guidance on proper installation and inspection of connections. Finally, it stresses the importance of testing the completed system to ensure it is effective.
A slide presentation from Rob Shoaf delivered at the Feb. 9, 2011 Gas/Electric Partnership Conference XIX in Cypress, TX. The presentation dealt with the phenomenon of AC electricity running through high voltage lines potentially corroding nearby underground pipelines--and how to mitigate potential problems.
The document discusses issues related to AC corrosion on pipelines located near high-voltage power lines. It provides background on how AC current can be induced in pipelines and details signs of AC corrosion observed in inspections. Thresholds of AC current density are discussed as indicators of potential corrosion risk. Methods for mitigating AC safety hazards and corrosion are described, including installing linear drain systems and deep point drains to divert current from the pipeline. Case studies show modeling and mitigation installation reducing pipeline voltages and current densities to safe levels.
Development of Over-Line Survey Systems for Monitoring Pipelines v1.0 - uploa...David Simmonds
1) Researchers developed an over-line survey system to measure AC voltage and current density on pipelines to identify areas at risk of AC-induced corrosion.
2) Field trials showed that readings from a standard copper wire underestimated actual AC current density by up to 60% due to inductive effects.
3) Models were created to calculate the true AC current density based on measurements and inductance values, resulting in estimates within 10% of actual values.
A substation directs the flow of power through the electric system, protects components from faults, and interconnects transmission lines. It requires careful planning and design to achieve reliability, flexibility, and minimize costs while satisfying electric system requirements. Key elements of substation design include bus configurations, equipment layout and spacing, foundations, protective relaying, surge protection, and environmental considerations. Proper substation design is essential for reliable electric system operation.
The topic mainly deals about different methods of high power Underground transmission systems currently implemented across the world as well as about the modern GIL systems.
It also explain about the advantages, construction and features of GIL (Gas Insulated Transmission Lines) by highlighting its future scope as well.
Europacable is an association of European cable manufacturers that promotes the use of XLPE cables for electricity transmission. They believe XLPE cables are a reliable and innovative technology that have manageable environmental impacts and comparable life-cycle costs to overhead lines. Partial undergrounding using XLPE cables can facilitate grid extension by addressing local concerns and enable the integration of renewable energy sources into Europe's future energy mix.
As the AIS (Air-Insulated Substation) is having more limitations, More and more people are going for the Gas-Insulated Substation which is environment friendly as well.
In these presentation, We discussed about theoritical and technological advancement and advantages related to GIS as compared to other substations.
We discussed different parts of the GIS as well as their operations and advantages.
By going through this presentation, you will have idea regarding comparative advantages and disadvantages of both substations.
This document discusses grounding and bonding testing procedures. It begins with an overview of the key steps: 1) performing an earth (soil) resistivity test, 2) installing the grounding system, and 3) testing the installed system. It then covers details of soil resistivity testing including how to measure resistivity and factors that affect resistivity. The document reviews components of a grounding system including electrodes, conductors, bars and connection methods. It provides guidance on proper installation and inspection of connections. Finally, it stresses the importance of testing the completed system to ensure it is effective.
Underground transmission cables have several advantages over overhead lines including improved reliability, reduced electromagnetic fields, and allowing construction over cable routes. However, they also have some disadvantages such as higher initial installation costs and difficulties locating faults. Maintenance and repair of underground cables can also be more complex than overhead lines. Overall, underground cables are well-suited for transmission at voltages up to around 115kV for distances of a few kilometers, but overhead lines are generally used for longer high voltage transmission.
Your electrical safety specilist for all equipments Powered AC and DCMahesh Chandra Manav
We all are aware that we are applying lots of Artficial Sources to make our Life Comforts .
For This we are installing Many Electrical Equipments Power AC & DC and Electric Vehicles Inside our Building and out Side and in this process many of metal Part is entering into our Building.
To ensure better perform and Human Safety Earthing of Equipment and Conductive stucture is very important Value from 1 Ohms up to 0.25 Ohms.
Our National Building Code 2016 is alreday given Guide Line and Supporting by MBBL2019
(Manual Building By LAW).
Internal Switch and External Lightning will very Danger for our Equipments and Human Lives May Cause Assest Damage up to Sacrifice Human Live due to Fire and Electric Change.
We have to Design and protect our Building or Permises form External Lightning by Nature use NBC IS/IEC 62305.
When Lightning Fall any Condutive Like Pole ,Transmission Line and React with Ground may be Shift 100kA Fault Current into our Building use Surge Protection Device to product from any ind of Direct and Indirect Threat.
JMV LPS Ltd belive Make in India Noida Base Company Manufacturer Design ,Engineering ,Supply and Installation.
Maintenance Free Earthing ,Copper Clad Steet Sof Conductore, Exothermic Weld, External Lightning Protection and per IS/IEC62305, Surge Protection Devive as per IS/IEC 62035.
1. The document provides an overview of a training module on overhead line work. It covers power system structure, design principles of distribution lines, and installing/maintaining electrical equipment.
2. The objectives are to address distribution line problems, energize 33kV lines, develop awareness of installing/maintaining 33kV lines, and discuss insulation and equipment selection.
3. The target group are trainees in categories S1-S4 and W3-W6.
This document provides a summary of a book that covers cable installation and serves as a reference for electrical engineers and other professionals. The book comprehensively covers aspects of cable estimation, installation, testing and commissioning. It addresses concepts of cable construction, application and sizing, insulating materials, conductor types, communication cables, fault location, testing equipment, installation procedures, sheath earthing, and terminology. The content is intended to help electrical engineers, designers, contractors and others working with cable installation.
Factors considered for High Voltage Cable Joint design Shahab Khan
This document discusses key factors to consider for high voltage cable joint design. It outlines several important design factors, including the types of cables being joined, voltage levels, expected transient overvoltages, number of phases, dielectric strength of interfaces, choice of materials, and location of installation. The document emphasizes that cable joints are vulnerable points that require reliable designs to ensure good thermal performance, electrical stress control, and environmental and mechanical protection. Proper consideration of cable joint design factors is important for safety and long-term reliability of cable systems.
This document provides guidance on earthing practices for Central Networks. It outlines significant recent changes, including the classification of distribution sites as either "Hot" or "Cold" based on their connection type. It describes the requirements for segregating high voltage and low voltage earths at distribution sites. The document also reviews the various earthing methods used on Central Networks' high voltage transmission and distribution networks.
The document summarizes a seminar presentation on gas insulated substations (GIS). It defines GIS as substations that use sulfur hexafluoride gas (SF6) as an insulating medium to allow for a compact design. The document outlines the key internal equipment of GIS, including circuit breakers, disconnectors, buses, transformers, and more. It discusses the advantages of GIS such as reduced space requirements and reliability. GIS are well-suited for applications requiring a small footprint, such as urban or indoor installations.
The document discusses gas insulated substations (GIS), which use sulfur hexafluoride (SF6) gas as the insulating medium within an enclosed metal housing. GIS offer advantages over traditional air insulated substations (AIS), as they occupy less space, have higher reliability, and require less maintenance. The key components of a GIS include gas insulated busbars, circuit breakers, disconnectors, earthing switches, and voltage and current transformers. While more expensive initially, GIS allow for more compact and reliable substation design in space-constrained urban areas. Some concerns with GIS include the environmental impact of SF6 and the challenges associated with diagnosing and repairing internal
The document discusses the pros and cons of underground vs overhead transmission and distribution of electric power. It notes that while underground lines have fewer outages due to weather, they are much more expensive - up to 20 times as costly as overhead lines. It also discusses various technical limitations of underground transmission lines related to line capacitance and voltage regulation over long distances. The document concludes that while selective underground installation is possible, replacing all overhead lines in a state with underground is not practical or possible given the high costs and technical limitations.
High Voltage Gas Insulted Switchgear (GIS) Field Testing According to IEEE C3...Ali Sepehri
High Voltage Gas Insulted Switchgear (GIS) Field Testing According to IEEE C37.122
Article direct link: https://www.linkedin.com/pulse/high-voltage-gas-insulted-switchgear-gis-field-testing-ali-sepehri/
Follow India national building code(NBC2016) for electrical installation and ...Mahesh Chandra Manav
We are all aware now days getting new Regarding Fire Accident and Claiming Due to short circuit and Died and Causality one or two Days Serious Comment by Political Party later forget .
if we are all keep our irresponsible and some people personal interest pass un authorized Construction by Electrical Inspector and Fire and Safety Personal Later People Build Unauthorized Changes .
all this is not Secret known by respected agencies they only interest to Satisfy their personal need by culprit.
If we as citizen not allow and follow strictly NBC2016 for Electrical Installation.
JMV LPS LTD will support all Industries , Consultants and End User require Earthing for Equipment's Follow IS3043(2018), Grid Earthing IEEE80 , NBC2016 Lightning Protection , Exothermic Weld , Copper Clad Steel Conductors and Surge Protection for Power Data and Communication .
We have CDEGS Software , for Design Earthing , IEC62305 for Lightning and LAB for Testing 200kA 10/350 ,50kA 8/20 Surge High Voltage 550KV accerlate with NABL and according to IEC
Plz Call for Design , Presentation Mahesh Chandra Manav M-9910398999 manav@jmv.co.in
Copper and aluminum compared in a life-cycle cost perspectiveLeonardo ENERGY
In this presentation, the results of two studies are presented. The first study concerns a survey of technical properties of copper versus aluminium, including failure mechanisms in which the conductor plays a major part, followed by a decision model on what criteria the selection process of the conductor material happens in practice. The second study deals with a complete Life Cycle Cost Analysis, in which the total life-cycle costs are being calculated over the life span of the cable with both CAPEX and OPEX. This has resulted in the conclusion that both materials can be considered to give equivalent solutions from a life cycle costing perspective. These studies demonstrate a superiority of copper while costs are similar. Although there is a difference in initial costs, such initial conductor and cable costs represent only a negligible (a few percentage) portion of the total life cycle cost.
This document provides an overview of substation and switchgear fundamentals, including:
1. It describes the components of electrical substations and switchgear such as transformers, circuit breakers, control systems, and communication networks.
2. It discusses electrical concepts like voltage, current, nominal current, short circuit current, and arc flash hazards.
3. It covers substation and switchgear design criteria including safety standards, equipment clearances, and personnel protection from arc flash.
This document discusses gas insulated substations (GIS). It begins by defining substations and their purpose in the electric power system. It then discusses the classifications of substations and compares air insulated substations (AIS) to GIS. GIS use sulfur hexafluoride gas for insulation inside grounded metal enclosures, making them more compact than AIS. The document outlines the components, advantages, and operating conditions of GIS, noting they require less maintenance and space than AIS. It concludes with growth projections for the global GIS market.
The document compares overhead and underground transmission systems. Underground transmission requires specialized engineering skills and extensive study due to subsurface obstacles. It has longer timeframes for design and construction due to needing space for large vaults and trenches. Maintenance is also more difficult and expensive for underground lines. Overall, underground transmission costs 8 to 10 times more than equivalent overhead systems due to higher construction and lifetime costs. However, underground transmission may have fewer outages and is used in dense urban areas where overhead lines are not feasible.
EE2353 / High Voltage Engineering - Testing of CablesRajesh Ramesh
Cable testing is important to ensure the long life and high efficiency of cables used for high voltage transmission. There are several types of tests conducted on cable samples including mechanical, thermal, impulse withstand voltage, partial discharge, and dielectric power factor tests. Partial discharge tests are particularly important for determining the life of cable insulation by detecting internal discharges under voltage stress. These tests are conducted at various stages of voltage levels on cable samples to certify them for transmission use.
Comparison of overhead and underground transmission linesahmed usama
Overhead transmission lines are the lowest-cost method for transmitting large quantities of electricity over long distances. They operate at voltages from low to ultra high and consist of conductors suspended by towers. While overhead lines have lower installation and repair costs and less environmental impact than underground lines, undergrounding provides benefits like reduced outages from severe weather and lower electromagnetic field emissions. However, underground lines have significantly higher construction costs, longer repair times, and greater risks from ground movement.
Performances of distribution transformer installed in metallic enclosuresnehakardam
This document discusses the performance of distribution transformers installed in metallic enclosures in Australia. It notes that compact substations with transformers experience harsh service conditions. Distribution transformers in Australia rated 750-2000 KVA are highlighted for their unique design, loading capability, reliability, and safety features. The document also examines factors affecting transformer life like ambient temperatures, loading levels, and the impact of enclosures on temperature rises. It presents methods to assess temperature increases in transformer compartments due to kiosk enclosures and confirms calculated temperature rises through heat-run tests.
Assuring Reliability of Critical Power Cable Systemsmichaeljmack
The document discusses testing methods for assuring the reliability of critical power cable systems. It states that high potential (HIPOT) tests are intentionally destructive and do not assure reliability. The best practice for assuring a cable system meets its design life is repeating the manufacturer's offline 50/60Hz partial discharge (PD) quality control test in the field, as this is the only effective way to assure the insulation system meets specifications. Over the last decade, one diagnostic technology, defect specific diagnostics (DSD), has been proven to effectively reproduce comparable factory test results in the field.
This document discusses issues that can arise when pipelines and HVAC power lines are collocated within the same right of way. It describes three main types of interference between pipelines and AC power: electrostatic coupling causing nuisance effects, conductive coupling resulting in fault currents, and inductive coupling producing steady-state induced AC voltages. Mitigation of these interference effects typically involves installing grounding devices to discharge AC current away from the pipeline in order to reduce coating stress and induced voltages below safety and corrosion thresholds. Computer modeling can assess mitigation options, but has limitations due to assumptions. Field testing provides direct measurements of conditions.
This document discusses corona, which is a luminous discharge that occurs when the electric field intensity near a conductor exceeds the critical disruptive voltage of air. Corona can cause audible noise, radio interference, and power loss. The critical disruptive voltage depends on factors like conductor size and spacing, air density, humidity, and the conductor surface condition. Larger or bundled conductors can increase the critical voltage and reduce corona by distributing the electric field. While corona provides some benefits like reducing transient effects, it primarily disadvantages like energy loss, ozone production, and interference. The document provides formulas to calculate the critical disruptive voltage under different conditions.
Underground transmission cables have several advantages over overhead lines including improved reliability, reduced electromagnetic fields, and allowing construction over cable routes. However, they also have some disadvantages such as higher initial installation costs and difficulties locating faults. Maintenance and repair of underground cables can also be more complex than overhead lines. Overall, underground cables are well-suited for transmission at voltages up to around 115kV for distances of a few kilometers, but overhead lines are generally used for longer high voltage transmission.
Your electrical safety specilist for all equipments Powered AC and DCMahesh Chandra Manav
We all are aware that we are applying lots of Artficial Sources to make our Life Comforts .
For This we are installing Many Electrical Equipments Power AC & DC and Electric Vehicles Inside our Building and out Side and in this process many of metal Part is entering into our Building.
To ensure better perform and Human Safety Earthing of Equipment and Conductive stucture is very important Value from 1 Ohms up to 0.25 Ohms.
Our National Building Code 2016 is alreday given Guide Line and Supporting by MBBL2019
(Manual Building By LAW).
Internal Switch and External Lightning will very Danger for our Equipments and Human Lives May Cause Assest Damage up to Sacrifice Human Live due to Fire and Electric Change.
We have to Design and protect our Building or Permises form External Lightning by Nature use NBC IS/IEC 62305.
When Lightning Fall any Condutive Like Pole ,Transmission Line and React with Ground may be Shift 100kA Fault Current into our Building use Surge Protection Device to product from any ind of Direct and Indirect Threat.
JMV LPS Ltd belive Make in India Noida Base Company Manufacturer Design ,Engineering ,Supply and Installation.
Maintenance Free Earthing ,Copper Clad Steet Sof Conductore, Exothermic Weld, External Lightning Protection and per IS/IEC62305, Surge Protection Devive as per IS/IEC 62035.
1. The document provides an overview of a training module on overhead line work. It covers power system structure, design principles of distribution lines, and installing/maintaining electrical equipment.
2. The objectives are to address distribution line problems, energize 33kV lines, develop awareness of installing/maintaining 33kV lines, and discuss insulation and equipment selection.
3. The target group are trainees in categories S1-S4 and W3-W6.
This document provides a summary of a book that covers cable installation and serves as a reference for electrical engineers and other professionals. The book comprehensively covers aspects of cable estimation, installation, testing and commissioning. It addresses concepts of cable construction, application and sizing, insulating materials, conductor types, communication cables, fault location, testing equipment, installation procedures, sheath earthing, and terminology. The content is intended to help electrical engineers, designers, contractors and others working with cable installation.
Factors considered for High Voltage Cable Joint design Shahab Khan
This document discusses key factors to consider for high voltage cable joint design. It outlines several important design factors, including the types of cables being joined, voltage levels, expected transient overvoltages, number of phases, dielectric strength of interfaces, choice of materials, and location of installation. The document emphasizes that cable joints are vulnerable points that require reliable designs to ensure good thermal performance, electrical stress control, and environmental and mechanical protection. Proper consideration of cable joint design factors is important for safety and long-term reliability of cable systems.
This document provides guidance on earthing practices for Central Networks. It outlines significant recent changes, including the classification of distribution sites as either "Hot" or "Cold" based on their connection type. It describes the requirements for segregating high voltage and low voltage earths at distribution sites. The document also reviews the various earthing methods used on Central Networks' high voltage transmission and distribution networks.
The document summarizes a seminar presentation on gas insulated substations (GIS). It defines GIS as substations that use sulfur hexafluoride gas (SF6) as an insulating medium to allow for a compact design. The document outlines the key internal equipment of GIS, including circuit breakers, disconnectors, buses, transformers, and more. It discusses the advantages of GIS such as reduced space requirements and reliability. GIS are well-suited for applications requiring a small footprint, such as urban or indoor installations.
The document discusses gas insulated substations (GIS), which use sulfur hexafluoride (SF6) gas as the insulating medium within an enclosed metal housing. GIS offer advantages over traditional air insulated substations (AIS), as they occupy less space, have higher reliability, and require less maintenance. The key components of a GIS include gas insulated busbars, circuit breakers, disconnectors, earthing switches, and voltage and current transformers. While more expensive initially, GIS allow for more compact and reliable substation design in space-constrained urban areas. Some concerns with GIS include the environmental impact of SF6 and the challenges associated with diagnosing and repairing internal
The document discusses the pros and cons of underground vs overhead transmission and distribution of electric power. It notes that while underground lines have fewer outages due to weather, they are much more expensive - up to 20 times as costly as overhead lines. It also discusses various technical limitations of underground transmission lines related to line capacitance and voltage regulation over long distances. The document concludes that while selective underground installation is possible, replacing all overhead lines in a state with underground is not practical or possible given the high costs and technical limitations.
High Voltage Gas Insulted Switchgear (GIS) Field Testing According to IEEE C3...Ali Sepehri
High Voltage Gas Insulted Switchgear (GIS) Field Testing According to IEEE C37.122
Article direct link: https://www.linkedin.com/pulse/high-voltage-gas-insulted-switchgear-gis-field-testing-ali-sepehri/
Follow India national building code(NBC2016) for electrical installation and ...Mahesh Chandra Manav
We are all aware now days getting new Regarding Fire Accident and Claiming Due to short circuit and Died and Causality one or two Days Serious Comment by Political Party later forget .
if we are all keep our irresponsible and some people personal interest pass un authorized Construction by Electrical Inspector and Fire and Safety Personal Later People Build Unauthorized Changes .
all this is not Secret known by respected agencies they only interest to Satisfy their personal need by culprit.
If we as citizen not allow and follow strictly NBC2016 for Electrical Installation.
JMV LPS LTD will support all Industries , Consultants and End User require Earthing for Equipment's Follow IS3043(2018), Grid Earthing IEEE80 , NBC2016 Lightning Protection , Exothermic Weld , Copper Clad Steel Conductors and Surge Protection for Power Data and Communication .
We have CDEGS Software , for Design Earthing , IEC62305 for Lightning and LAB for Testing 200kA 10/350 ,50kA 8/20 Surge High Voltage 550KV accerlate with NABL and according to IEC
Plz Call for Design , Presentation Mahesh Chandra Manav M-9910398999 manav@jmv.co.in
Copper and aluminum compared in a life-cycle cost perspectiveLeonardo ENERGY
In this presentation, the results of two studies are presented. The first study concerns a survey of technical properties of copper versus aluminium, including failure mechanisms in which the conductor plays a major part, followed by a decision model on what criteria the selection process of the conductor material happens in practice. The second study deals with a complete Life Cycle Cost Analysis, in which the total life-cycle costs are being calculated over the life span of the cable with both CAPEX and OPEX. This has resulted in the conclusion that both materials can be considered to give equivalent solutions from a life cycle costing perspective. These studies demonstrate a superiority of copper while costs are similar. Although there is a difference in initial costs, such initial conductor and cable costs represent only a negligible (a few percentage) portion of the total life cycle cost.
This document provides an overview of substation and switchgear fundamentals, including:
1. It describes the components of electrical substations and switchgear such as transformers, circuit breakers, control systems, and communication networks.
2. It discusses electrical concepts like voltage, current, nominal current, short circuit current, and arc flash hazards.
3. It covers substation and switchgear design criteria including safety standards, equipment clearances, and personnel protection from arc flash.
This document discusses gas insulated substations (GIS). It begins by defining substations and their purpose in the electric power system. It then discusses the classifications of substations and compares air insulated substations (AIS) to GIS. GIS use sulfur hexafluoride gas for insulation inside grounded metal enclosures, making them more compact than AIS. The document outlines the components, advantages, and operating conditions of GIS, noting they require less maintenance and space than AIS. It concludes with growth projections for the global GIS market.
The document compares overhead and underground transmission systems. Underground transmission requires specialized engineering skills and extensive study due to subsurface obstacles. It has longer timeframes for design and construction due to needing space for large vaults and trenches. Maintenance is also more difficult and expensive for underground lines. Overall, underground transmission costs 8 to 10 times more than equivalent overhead systems due to higher construction and lifetime costs. However, underground transmission may have fewer outages and is used in dense urban areas where overhead lines are not feasible.
EE2353 / High Voltage Engineering - Testing of CablesRajesh Ramesh
Cable testing is important to ensure the long life and high efficiency of cables used for high voltage transmission. There are several types of tests conducted on cable samples including mechanical, thermal, impulse withstand voltage, partial discharge, and dielectric power factor tests. Partial discharge tests are particularly important for determining the life of cable insulation by detecting internal discharges under voltage stress. These tests are conducted at various stages of voltage levels on cable samples to certify them for transmission use.
Comparison of overhead and underground transmission linesahmed usama
Overhead transmission lines are the lowest-cost method for transmitting large quantities of electricity over long distances. They operate at voltages from low to ultra high and consist of conductors suspended by towers. While overhead lines have lower installation and repair costs and less environmental impact than underground lines, undergrounding provides benefits like reduced outages from severe weather and lower electromagnetic field emissions. However, underground lines have significantly higher construction costs, longer repair times, and greater risks from ground movement.
Performances of distribution transformer installed in metallic enclosuresnehakardam
This document discusses the performance of distribution transformers installed in metallic enclosures in Australia. It notes that compact substations with transformers experience harsh service conditions. Distribution transformers in Australia rated 750-2000 KVA are highlighted for their unique design, loading capability, reliability, and safety features. The document also examines factors affecting transformer life like ambient temperatures, loading levels, and the impact of enclosures on temperature rises. It presents methods to assess temperature increases in transformer compartments due to kiosk enclosures and confirms calculated temperature rises through heat-run tests.
Assuring Reliability of Critical Power Cable Systemsmichaeljmack
The document discusses testing methods for assuring the reliability of critical power cable systems. It states that high potential (HIPOT) tests are intentionally destructive and do not assure reliability. The best practice for assuring a cable system meets its design life is repeating the manufacturer's offline 50/60Hz partial discharge (PD) quality control test in the field, as this is the only effective way to assure the insulation system meets specifications. Over the last decade, one diagnostic technology, defect specific diagnostics (DSD), has been proven to effectively reproduce comparable factory test results in the field.
This document discusses issues that can arise when pipelines and HVAC power lines are collocated within the same right of way. It describes three main types of interference between pipelines and AC power: electrostatic coupling causing nuisance effects, conductive coupling resulting in fault currents, and inductive coupling producing steady-state induced AC voltages. Mitigation of these interference effects typically involves installing grounding devices to discharge AC current away from the pipeline in order to reduce coating stress and induced voltages below safety and corrosion thresholds. Computer modeling can assess mitigation options, but has limitations due to assumptions. Field testing provides direct measurements of conditions.
This document discusses corona, which is a luminous discharge that occurs when the electric field intensity near a conductor exceeds the critical disruptive voltage of air. Corona can cause audible noise, radio interference, and power loss. The critical disruptive voltage depends on factors like conductor size and spacing, air density, humidity, and the conductor surface condition. Larger or bundled conductors can increase the critical voltage and reduce corona by distributing the electric field. While corona provides some benefits like reducing transient effects, it primarily disadvantages like energy loss, ozone production, and interference. The document provides formulas to calculate the critical disruptive voltage under different conditions.
Chapter Five Corona and Overhead line Insulators.pptxssuserc8d444
Corona and overhead line insulators are discussed. Corona occurs when the electrostatic stress around a conductor exceeds 30 kV/cm, producing a faint glow and noise. It causes power loss and radio interference. Several factors affect corona like conductor size, spacing, voltage, frequency, and atmosphere. Insulators provide insulation between conductors and supports to prevent leakage currents. Common materials are porcelain, glass, and synthetic resin. Different types of insulators include pin, suspension, strain, shackle, and stay insulators. The potential is unevenly distributed in a suspension insulator string due to shunt capacitances. Methods to improve string efficiency include using a longer crossarm or grading insulator units.
HVDC systems remain the best option for long-distance bulk power transmission and connecting asynchronous grids. They allow for more economical and environmentally friendly power transmission compared to HVAC systems in these conventional applications. However, advances in technology, deregulation of electricity markets, and environmental protection efforts are increasing the viability of HVDC systems for additional situations where high voltage AC transmission was previously preferred.
This document provides information about major components of a distribution system including transformers, circuit breakers, lightning arresters, switches, insulators, busbars, capacitor banks, and fencing. It also discusses requirements for distribution systems like reliability and limited voltage fluctuations. Distribution systems are classified based on construction (overhead vs underground), current type (DC vs AC), and connection scheme (radial, ring main, interconnected). The key difference between a feeder and distributor is that a feeder transmits power without taps while a distributor has taps to deliver power to consumers. A ring main distribution forms a closed loop to improve reliability and ensure uninterrupted supply if a feeder faults. The document also covers voltage drop calculation in
This document discusses the importance of proper grounding and bonding for electrical systems. It defines key terms like grounding, bonding, and ground loops. The primary objectives of grounding are safety, fault protection, and creating a signal reference ground. Improper grounding can cause problems like earth loops, electromagnetic interference, loose connections, and reduced protection. The document outlines requirements for grounding in the National Electrical Code and describes components of effective grounding systems, including ground electrodes, conductors, and techniques like single-point and multipoint grounding. Signal reference grounds are important for sensitive equipment. Overall, the document emphasizes that proper grounding is fundamental to ensuring electrical system stability and preventing shock hazards.
This document discusses several methods for measuring high DC voltages:
1. Series resistance micrometers measure voltage by passing a known small current through a high-value resistor and measuring the voltage drop, allowing measurement up to 500kV.
2. Resistance potential dividers use two high-value resistors to proportionally step down a high voltage to a measurable level.
3. Generating voltmeters induce a small current proportional to the measured voltage without a direct connection.
4. Sphere gaps measure peak voltages up to 2500kV by measuring the sparkover voltage between two conductive spheres. Atmospheric conditions and spacing accuracy affect measurements.
This document provides information about a power system protection course, including:
1. The syllabus covers 5 units - introduction to protection schemes, operating principles of relays, apparatus protection, theory of circuit interruption, and circuit breakers.
2. The theory of circuit interruption unit discusses arc phenomena, interruption of DC and AC circuits. It explains the physics behind arc initiation, maintenance and methods of arc extinction.
3. Interruption of capacitive current can produce high transient voltages across the circuit breaker contacts. This occurs when unloaded transmission lines or capacitor banks are switched off.
Alternating current (AC) is the main driving force in the industries and residential areas, but for the long transmission line (more than 650 KM) AC transmission is more expensive than that of direct current (DC). Technically, AC transmission line control is more complicated because of the frequency. DC transmission does not have these limitations, which has led to build long HVDC transmission lines over the last 40 years. HVDC technology made possible to transfer bulk power over long distances.
Circuit breakers are switching devices that can make, carry, and break electric currents under both normal and abnormal circuit conditions. They contain fixed and moving contacts that remain closed during normal operation but open automatically during faults to interrupt the fault current. When contacts open under fault conditions, an arc is produced that must be quickly extinguished. Different circuit breakers use various mediums like oil, air, vacuum, or SF6 gas to rapidly quench the arc through cooling and increasing dielectric strength between contacts. Common types of circuit breakers include oil, vacuum, air blast, and SF6 breakers that vary based on voltage level, switching speed, maintenance needs, and arc quenching method.
Loadability of line is defined as the extent of load which can flow through the line without exceeding the limitations. Line Loadability is expressed in percentage of Surge Impedance Loading of line. The limiting factor for line loading are: thermal limit, voltage drop limit and steady state stability.
This document discusses different types of circuit breakers and their operating principles. It describes how circuit breakers interrupt current by extinguishing the arc that forms between contacts. Vacuum circuit breakers use vacuum as the arc quenching medium, allowing for quick arc extinction due to rapid condensation. Sulfur hexafluoride circuit breakers use SF6 gas, which absorbs electrons from the arc. Air-blast circuit breakers employ high pressure air to cool and sweep away the arc.
This document discusses various aspects of circuit breakers, including their design and operation. It describes how an arc is maintained between contacts during arcing periods and how factors like ionization, arc length and cross-section affect the arc resistance. It then discusses two main methods of arc extinction - the high resistance method which involves lengthening or cooling the arc, and the low resistance method which causes ionized particles to recombine. The document also covers topics like current chopping in air-blast circuit breakers, interruption of capacitive currents, classifications of circuit breakers, and the operation of different types of circuit breakers including oil, vacuum, SF6, and air blast.
PN junction diodes have two modes of reverse breakdown:
1. Zener breakdown occurs at lower voltages (<5V) due to electric fields breaking covalent bonds.
2. Avalanche breakdown happens at higher voltages (>7V) when carriers gain enough energy to break bonds upon collision.
3. Both mechanisms generate electron-hole pairs that increase the reverse current across the junction.
Non-destructive testing (NDT) involves analysis techniques used to evaluate materials, components, or systems without damaging them. NDT is used to determine properties like resistivity, dielectric constant, and loss factor of insulating materials. It helps ensure materials maintain their insulating properties during operation. Two common methods for measuring dielectric loss and loss angle of insulating materials are the Schering bridge and transformer ratio arm bridge. The loss angle tan δ indicates the quality of insulation and can determine material life expectancy. Partial discharges within insulating materials are detected using NDT and indicate weaknesses.
This document provides an overview of the High Voltage Engineering course code EE-4123. The summary includes:
1) The course covers topics such as high voltage DC circuits, high voltage AC circuits, impulse voltages, insulation testing, HVDC transmission, corona effects, high voltage measurement and testing, and overvoltage protection.
2) The objectives of the course are to teach students about different voltage levels, applications of high voltage, electrical insulation, dielectric materials, and breakdown mechanisms in solid, liquid, and gaseous dielectrics.
3) High voltage is defined as voltages above 11kV for power systems, with classifications of up to 100kV as high voltage, 100kV-400
This document provides an overview of the High Voltage Engineering course code EE-4123. The summary includes:
1) The course covers topics such as high voltage DC circuits, high voltage AC circuits, impulse voltages, insulation testing, HVDC transmission, corona effects, high voltage measurement and testing, and overvoltage protection.
2) The objectives of the course are to teach students about different voltage levels, applications of high voltage, electrical insulation, dielectric materials, and breakdown mechanisms in solid, liquid, and gaseous dielectrics.
3) High voltage is defined as voltages above 11kV for power systems, with classifications of very high voltage from 100kV-400kV and extra high
The document discusses the increasing use of DC-DC converters in modern electronic systems to provide lower and lower DC voltages from higher DC inputs to power microelectronic circuitry. It notes that DC-DC converters generate both conducted and radiated electromagnetic interference. The interference is caused by the switching action of the converters and can degrade system performance if not properly mitigated. The document focuses on power line input filters used with DC-DC converters, explaining that simple LC filters can potentially cause instability due to the negative input impedance behavior of switching regulators. It proposes a design strategy using models of the converter and filter to ensure stability while providing sufficient interference attenuation.
This document discusses the benefits of natural gas. It notes that natural gas supports millions of American jobs and national security by providing a domestic energy source. The shale gas revolution has unlocked vast domestic natural gas supplies in the United States through innovations like horizontal drilling and hydraulic fracturing. As natural gas production has increased, prices have remained stable and even dropped for industrial users and consumers in states like Florida, saving billions per year. The document also discusses how new pipeline infrastructure is expanding access to natural gas across the United States.
This document summarizes developments in oil pipeline expansions and safety. It notes significant growth in North American energy production from various basins that will enable energy independence by 2024 with expanded pipeline infrastructure on the East and West Coasts. It outlines numerous pipeline expansion projects. It also discusses recent significant pipeline accidents and increased regulatory safety oversight activity. It outlines the oil pipeline industry's safety principles and initiatives to continuously improve safety performance through measurement, learning, technology, and stakeholder engagement.
This document discusses how leadership influences safety culture at NASA and energy pipeline organizations. Both deal with critical, high-risk operations involving fuel and complex lifting. While processes are important, people and culture truly drive safety. Leaders must share their vision of safety as the top priority, foster open communication to address concerns, and brand their organization's culture of prioritizing safety through inspiration and connection. A strong, positive culture cultivated by leadership can empower teams to take pride in their work and leave a lasting legacy of safety.
Larry Hjalmarson is the Vice President of Safety, Environmental and Pipeline Integrity at Williams Gas Pipeline. Williams Gas Pipeline operates over 15,000 miles of natural gas transmission pipelines across 21 states. Hjalmarson discussed Williams' commitment to safety culture and mitigating threats to pipelines from external and internal corrosion, manufacturing and construction defects, equipment issues, excavation damage, and other threats. He also outlined Williams' integrated approach to risk assessment and prevention and mitigation activities under its integrity management program.
Safety is a shared responsibility across all levels in a multi-employer worksite. Project owners, general contractors, subcontractors, and employees each play a role. An effective safety culture requires accountability from management to set clear expectations and empower workers. Incidents often stem from organizational and cultural failures, not solely human error. All parties must prioritize safety over other objectives like schedules and costs.
The document discusses best practices for verifying maximum allowable operating pressure (MAOP) based on guidance from PHMSA, including developing a specific verification plan, identifying key criteria and required records, determining the completeness and validity of record sources, and properly scanning applicable records to avoid future loss and establish traceability.
The document discusses Florida's statewide environmental resource permitting (ERP) program. It provides three purposes of the ERP program: to protect water quality, manage water quantity and flood protection, and protect wetland functions and other environmental resources. It also discusses the legislative intent of the statewide ERP rule to simplify and streamline the permitting process, increase consistency, and retain regional differences. The statewide ERP rule will consolidate the existing regional rules into a single rule and standardize permitting thresholds and criteria.
This document discusses wetland and stream restoration techniques used following an oil spill from Enbridge's Line 6B pipeline into Talmadge Creek and the Kalamazoo River in Marshall, Michigan in July 2010. Design concepts included creating representative cross sections, assessing shear stresses and plant communities, and using coir logs, backfill, seed mixes, and other materials. Implementation involved restoring creek banks and installing structures like rock chutes, ramps, and wildlife habitat features. Post-restoration monitoring showed regrowth of vegetation and stabilization of restored areas over time. Unique techniques addressed heavy groundwater flows and unconsolidated soils.
The document discusses safety culture in the pipeline industry, defining it as the behaviors and beliefs developed through training that result in preventing incidents, injuries, and losses. It emphasizes that safety must be a core value, not just the number one priority, and that all accidents are preventable by focusing on safe behaviors and decision making through improved training, education, and coaching of the workforce from management. The purpose is to provide methods for observing worksites to identify and correct unsafe behaviors and conditions through casual, special, and formal observations coupled with coaching employees to ensure their safety.
The State Emergency Operations Center (SEOC) coordinates Florida's response to emergencies and disasters. For minor emergencies, the SEOC monitors the situation with limited staff, but activates more fully for major events. The SEOC receives information, identifies resource needs, and keeps officials and partners informed. It provides direction, executes response strategies, and adjusts operations as needed. The State Watch Office within the SEOC is staffed 24/7 to communicate with counties and respond to routine issues, assessing resource needs and coordinating the initial response. Local governments own response and recovery efforts, with state and federal support when needed, such as during a 1998 natural gas pipeline explosion in Perry, Florida.
This document discusses integrity management and external corrosion direct assessment (ECDA) over a 10 year period. It provides an overview of ECDA as a 4 step process including pre-assessment, indirect inspection, direct examination, and post assessment. Congress required pipeline operators to implement integrity management programs, including conducting baseline assessments using methods like ECDA, to help prevent pipeline failures and protect public safety. ECDA aims to locate potential corrosion issues to prioritize repairs and reassess pipelines over time. The document outlines each step of ECDA and emphasizes following the full process is important for ensuring pipeline integrity.
The document summarizes Berne L. Mosley's presentation at the 23rd Annual Summer Symposium of the Florida Energy Pipeline Association on July 19, 2012. The presentation discusses trends in the natural gas pipeline industry driven by increased shale gas production, including changes in pipeline flow patterns, pending and approved pipeline projects, LNG export terminal status, and applications to export domestically produced LNG. The presentation also summarizes a DOE/EIA study finding that increased LNG exports would lead to higher domestic natural gas prices but also increased domestic production and reduced consumption.
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This presentation is a curated compilation of PowerPoint diagrams and templates designed to illustrate 20 different digital transformation frameworks and models. These frameworks are based on recent industry trends and best practices, ensuring that the content remains relevant and up-to-date.
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20. Design for Six Sigma (DFSS)
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2. Pipelines & HVAC Lines Collocated
• Collocated Utilities
Pipelines and HVAC Power
Lines often share the same
right of way
There are problems that
must be addressed when
HVAC and buried pipelines
share the same right of way
3. Enhanced Regulatory Scrutiny
• Regulators are focusing more on this issue given recent risk
findings by operators and enhanced pipeline safety regulations
• NACE Standard RP0177 (Latest Revision) - Recommended Practice
on Mitigation of Alternating Current & Lightning Effects on
Metallic Structure and Corrosion Control Systems. Also, ANSI/IEEE
Standard 80 specifies safety design criteria for determining
maximum acceptable touch and step voltages during fault
conditions.
4. Three Distinct Issues
• Health and Safety of Personnel/Public/Livestock
Well known and easily fixed
• AC Fault Currents
Short duration occurring at a particular tower location
• AC Induced Corrosion
Not well understood but affects well coated pipe
Steady state condition
Can be quite damaging and intense
5. How do Pipelines and AC Interact
• Electrostatic Coupling
Capacitive nuisance effect
• Conductive Coupling
Fault Currents at tower footings
• Inductive Coupling
Steady State Induced AC voltage buildup
6. Electrostatic Coupling
Pipe and Power line create a circuit
of two capacitors in series. A
capacitor is a passive electronic
component consisting of a pair of
conductors separated by an
insulator (air)
7. Electrostatic Coupling
Can generate very high AC voltage
levels – but there is not enough
power to do much more than
create a minor electrostatic shock.
Generally a nuisance, however can
be an issue and grounding may be
required.
8. How do Pipelines and AC Interact
• Electrostatic Coupling
Capacitive nuisance effect
• Conductive Coupling
Fault Currents at tower footings
• Inductive Coupling
Steady State Induced AC voltage buildup
9. Conductive Coupling
AC Fault Conditions
•Relatively rare
•Short duration
•Generally due to weather
(lightning and high winds)
•Can be structural failure
Causes intense stressing of pipeline
coating and possibly the pipeline
wall
10. Conductive Couplings
• Rare occurrences that can result in significant current
discharging through the ground
• Separation distance of the pipeline from the fault is critical
• Soil resistivity is critical – note soil layering can affect current
path
• Requires arcing through the soil for a current path – not easy
11. How do Pipelines and AC Interact
• Electrostatic Coupling
Capacitive nuisance effect
• Conductive Coupling
Fault Currents at tower footings
• Inductive Coupling
Steady State Induced AC voltage buildup
12. Electromagnetic Induction
•A function of Line Current not
Voltage
•Power transferred is
I1 •Proportional to line
current
•Proportional to
parallelism
φ
•Inversely proportional to
separation distance
•Can result in high voltages on
I2 long sections of pipeline even
if the pipeline is grounded
13. Electromagnetic Induction
• Current through the HVAC lines generate a
Longitudinal Electric Field (LEF)
A B C • The separation between the phase conductors
has a significant effect on the LEF and increases
with separation
• Bundled buried conductors have no separation
and provide only a minimal effect on pipelines
14. Electromagnetic Induction
• The arrangement of A
B
A
B
phases on multiple C C
circuit HVAC lines can
Center Line Symmetric
have a large impact on
the LEF A C
B B
C A
Center Point Symmetric
15. Electromagnetic Induction
• If all characteristics are
perfectly uniform along
the pipeline/HVAC then
there will be a zero
voltage at the mid point 0 L
and peaks where the L/2
HVAC and pipeline
separate if the pipeline is
electrically “short”
17. What are the effects of Coupling
• Electrostatic Coupling
Capacitive nuisance effect
• Conductive Coupling
Fault Currents at tower footings
Safety Concern
Stress Voltage
• Inductive Coupling
Steady State Induced AC voltage buildup
Safety Concern
AC Induced Corrosion
18. Stress Voltage
AC Fault Conditions
•Relatively rare
•Short duration
•Rapid localized increase in voltage
•Can cause significant coating
damage
•Could result in a direct arc from
tower footing to pipeline heating
the metal quickly (burning a hole)
19. Steady State AC Corrosion
• Until recently not a concern for pipeline operators
• Published studies pre-1990s discounted AC corrosion as
a possibility
• Regulators not focused on this as a risk until quite
recently
20. German Experiments
• Pipeline failures in Germany in the early 90s on well
protected new pipelines puzzled investigators
• Previously, AC corrosion rates were not considered a
threat
• Testing on coupons with 1 cm2 holidays in low resistivity
soils found corrosion rates of 210 mpy on steel polarized
to 1800-2000 mV cse
21. Morphology of AC Corrosion
Round crater like corrosion with
deep pits typical of very active
corrosion
May have some false indications of
Microbiologically Induced Corrosion
Occurs in the presence of AC
Transmission and in some cases
Distribution lines
Likely in lower soil resistivities
22. Optimum Coating Holiday
• Testing has found that the optimum coating holiday size
for high AC Corrosion rates is between 1-3 cm2 coating
holiday.
• AC Current density is the key consideration
0-20 A/m2 no corrosion
20-100 A/m2 corrosion risk unpredictable
Above 100 A/m2 corrosion can be expected
23. Sample Calculation
Sample calculation for a
1 cm2 holiday in 10 ohm-
m soil
Even at very low AC
voltage levels this could
yield corrosion rates in
excess of 20 mpy even
with good CP applied
24. AC Voltage vs. Soil Resistivity
This graph shows the
holiday size and AC
Voltage required to
exceed the 100 A/m2
“corrosion can be
expected” threshold at
varying soil resistivities.
25. AC Induced Corrosion
• The higher the quality of the coating the greater the risk of
AC induced corrosion
• AC Induced corrosion with well coated pipelines can create
significant and rapid corrosion even at low levels of induced
AC Voltage even with good CP levels on pipeline
• Corrosion mechanism still being researched but evidence is
clear that it occurs
26. Safety Concerns
• High voltage levels either from induction (steady state)
or from fault conditions (rare and short duration)
present a danger to personnel
15 VAC threshold is well established by NACE
Based on release threshold calculations
Gradient Mats are well established for a long time in the
industry
27. Step and Touch Potential
During a fault condition or even steady
state AC Voltage presence on the 10 kV
pipeline can create a safety condition
at above ground structures (test
stations, valves, etc…)
The person touching the structure is
exposed to 2 kV touch potential while 9 kV
8 kV
the man standing is exposed to 1 kV in 7 kV
this diagram
29. AC Mitigation
AC Mitigation typically involves installation of
one or more grounding devices to allow AC
current to readily discharge off of the pipeline
thus minimizing coating stress during fault
conditions and reducing the inductive voltage
levels to well below any threshold for
personnel safety or AC induced corrosion.
30. Key Issues
1. Step and Touch potentials at above ground
appurtances (15 VAC NACE criteria)
2. Conductive coupling dumping excessive Fault
Current onto pipeline causing damage
3. Induced Voltage discharging through smaller
holidays on well coated pipelines causing AC
induced corrosion
31. AC Modeling
• Very complex mathematically to model
Numerous variables
Some very difficult to quantify
Requires input from utility on the operating conditions
Requires field data gathering
Different modeling software
PRCI, SES/CDEGS, ARC Engineering, Dabkowski, others…
32. Goals for AC Modeling
• Calculating Fault Condition Stress Values
• Calculating Induced Voltage at various points along the
model
• Evaluating Impact of Mitigation Measures
Where
How much
How effective
33. Shortcomings of Modeling
• Modeling is only as good as the data being used
• Modeling is only as good as the assumptions being
made
• Modeling has to focus on worst case conditions
34. What is being modeled
• The power line
Peak loads, winter and summer
Max fault current (line to ground)
Shield wire data – type and geometry (mostly for fault analysis –
only minor impact on steady state)
Phase wire data
Phase imbalance data
Tower data
35. What is being modeled
• The pipeline
Pipe diameter
Wall thickness
Depth of cover
Coating resistance and thickness (generally a guess since it is
not practical to measure this)
Centerline distance from towers
36. What is being modeled
• The environment
Soil resistivity along the colocation
Soil resistivity at various depths (used in some of the more
sophisticated modeling)
Foreign structures of note (multiple pipelines and multiple
HVAC lines)
38. Stress Currents
• The concern is elevated short duration coating stress.
Different coatings have different coating stress limits
• Computer modeling is very complex and requires
numerous assumptions
Geometry
Soil Resistivity and layering
Transmission Fault data
42. Risk Assessment w/o Modeling
• Look for changes that will cause voltage spikes
Changes in the pipeline to HVAC distance from each other
Changes in the HVAC line (phase transpositions)
Changes in soil resistivity
• Identify what your concerns might be
Stress voltages during fault conditions
Steady state AC induced corrosion
43. Risk Assessment w/o Modeling
• Corrosion risk - Zero in on areas where voltage spikes
can be anticipated and there is low soil resistivity.
• Fault current risk – Zero in on areas with the least
separation between tower footings and pipeline
• Modeling may not be required
44. Field testing of LEF
• It is possible to take AC voltage readings and to measure the
induced longitudinal electrical field (LEF) by placing a
calibrated insulated cable on the ground parallel to the
pipeline, grounding it, and using an high impedance
voltmeter to measure the open circuit potential
• The value received reflects the operating conditions at the
time
46. AC Test Coupons
• Designed to replicate a
1 cm2 holiday
• Can be used to
determine the actual
current density being
picked up at the
pipeline before
applying mitigation and
after installing
mitigation
• Uses the same coating
and geometry as the
pipe
49. Optimum AC Mitigation
• Modeling is only as good as the model, the assumptions and
the data being input
• Gradient control line(s) parallel to the pipeline for new well
coated pipelines are recommended to minimize AC Corrosion
risk
• Short lines at the tower footings are best for fault condition
mitigation and can be used in conjunction with long gradient
control lines
50. MATCOR’s MITIGATOR™
What is the MITIGATOR™?
Looks like the SPL™ Linear
Anode.
Not an anode but a copper
grounding cable
Special backfill
51. Installation
Installation of the MITIGATOR™ along a
Williams (Transco) Gas pipeline in Northern
New Jersey.
The pipeline is actually to the left of the
MITIGATOR™ trench.
The MITGATOR™ provides for easy installation,
a much larger surface area for discharging
copper, and the copper conductor is housed in
a special backfill with corrosion inhibitors.
52. From the Plattline™ Website
Life expectancy of Plattline in this application would be quite
long and would generally be determined by Plattline as a
projected cathodic protection system. The most common
sizes of Plattline for AC mitigation are plus and standard.
53. Zinc Ribbon
SIZE SURFACE AREA COST
Standard 54.0 mm2 $2.50/ft.
Plus 76.2 mm2 $5.00/ft.
Super 114.3 mm2 $9.50/ft.
MITIGATOR™ 119.6 mm2 $5.25/ft.
54. Concerns with Zinc
• Zinc can passivate and should have a special backfill when
used for AC Mitigation
• Zinc is much more difficult to handle and install relative to
the Mitigator™
• Must use a torch to make connections
• Requires more frequent use of decouplers
• Will consume over time – not as long a life as copper
55. Areas for more investigation
• Sophisticated modeling of Mitigator™ vs. Zinc
• Investigation of “propagation constant” and the spacing
of decouplers for zinc vs. Mitigator™
56. Summary of AC Interference
• There are three key threats
Safety (15 V AC Threshold)
Fault Conditions (rare but potentially damaging)
AC Corrosion – for new well coated pipelines this can easily be
the most challenging and difficult threat to control and can
cause damage even at lower levels of AC
57. Summary of AC Interference
• Modeling may not be fully effective – especially for AC
Corrosion
• AC Coupons give information based on current operating
conditions – changes in electrical flow affect the AC Induced
Voltage
• Risk Assessment can often be performed without expensive
modeling