Overview
Project Description
Key Research Question
Utility companies that own and operate underground distribution systems face a number of challenges and changing needs. Installing and maintaining underground infrastructure is challenging due to its accessibility. Additionally, installed underground distribution infrastructure is aging, and much of the early installed plant is reaching the end of its useful life. Utility managers are charged with managing costs, improving system reliability and resiliency, increasing power throughput, and improving the health and safety of workers and the public. In addition, significant changes to underground electric distribution systems are underway, including the application of new load types, new distributed generation sources, new equipment and materials, and automation technologies. At the same time, many utilities are losing their institutional knowledge due to worker attrition.
This research aims to support utilities in the face of these challenges by focusing on:
- Promoting technology transfer, via multiple vehicles, of the collated and created knowledge,
- Investigating the impact of increased electrification on the performance and reliability of both new and legacy underground infrastructure,
- Providing a framework with which to understand the common asset degradation mechanisms, informing enhanced specifications, diagnostics, and workmanship,
- Identifying effective approaches to improve reliability and extend the practical life of underground assets.
Objective
This objective of this research is to produce results to support utilities as they manage underground distribution systems, where the challenges include dealing with aging plant, assessing asset health and performance, improving specification and selection, and understanding and leveraging new technologies. This research also emphasizes knowledge capture and transfer to address the challenge of maintaining expertise in managing underground distribution systems.
Results take the form of reports, online repositories, and guidebooks, including periodic updates to the Underground Distribution Systems Reference Book (The Bronze Book).
Approach
Research will be provided in multiple forms, including:
- Results from experimentation and analysis
- Evaluation and demonstration of advanced tools and equipment
- Reference books, practical manuals, and field guides
- Workshops, meetings, and webcasts
2025 Research Tasks
In 2025, the Underground Assets project will consist of five primary research areas:
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Failure Analysis – Laboratory examination of failed components to identify common industry issues and mechanisms. With a particular focus on:
- Aged (age >25 year) medium voltage cable
- Transition cable joints (paper to extruded insulated cables)
- Cold-shrink cable joints
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Diagnostic Tools – Inform and investigate techniques (technologies, interpretation, and usability) that may be useful for determining the condition / health of underground components and systems, including:
- Condition / health
- Infrared thermography on medium voltage joints and separable connectors
- Dielectric loss (tan delta) for cable systems
- Commissioning tests for cable systems
- Online monitoring of underground systems for preventing manhole events
- Sharing of challenges (installation, communications, interpretation, etc.)
- Non-destructive fault locating techniques
- Condition / health
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Performance – Studies are intended to define / establish the behavior of components when operated under different conditions, including:
- Novel loading scenarios evolving from increased electrification,
- Laboratory aging and endurance studies
- Recently developed cable materials (lead-free EPR, EAM, etc.)
- Automation control cable aging
- Connectors
- Different conductors (Al / Cu and new/aged)
- Metallic sheath connections
- Modeling, using available information, the performance of padmounted and network transformers on overload situations.
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Asset Health – maintain critical asset operation through:
- Collecting PILC cable system fleet (medium and low voltage cables) information concerns and mitigation approaches
- Understanding equipment corrosion in underground structures
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Supply and Standards – Support for the development of industry standards of underground system components and methods for assessing supplier compliance with standards,
- Covered conductor (joint with 001)
- Factory assessment methodology
The five areas noted above will benefit from cross cutting activities of Knowledge Engineering and Technology Scouting which seeks to ensure that the key technical knowledge is delivered to members in the most useful manner, including:
- EPRI Underground Systems Reference Book (Bronze Book)
- Expand to include reference cable information developed in 2024,
- Separate Chapter 17 into four chapters: materials, qualification, quality, and manufacture.
- Development of online cable handbook on the Distribution Resource Center (http://distribution.epri.com)
- Gathering of key industry performance data
- Manhole events
- Cable system failure performance
- Cable installation / usage
- Tech scouting – WP
- “Articulate” cable limiter technology
- Medium voltage dc systems
- Network system data uses / potential
- Educational webinars and informational videos covering topics such as:
- Withstand (Proof ) Diagnostics
- Cable system ampacity
- Partial discharge
- Fundamentals of cables and accessories (stress distribution, materials)
- Basics of water treeing and the effects
- Manufacturing fundamentals
Research Value
With the knowledge acquired through this research program, distribution underground utility engineers and managers will have access to information and products that can accomplish the following:
- Improve specifications, inspection and maintenance approaches, and workmanship practices associated with underground switches and cable accessories
- Enhance strategic intelligence on emerging technologies
- Increase engineering staff expertise in underground distribution
- Improve the quality in underground distribution system design
- Lower underground distribution maintenance costs
- Gain more accurate and timely knowledge about asset condition and life expectancy
- Improve system reliability and safety and reduce environmental impacts
Task-Force Roles
The Underground Assets Task Force advises the Distribution Underground Assets Project. This task force is generally staffed by subject-matter experts in underground distribution components, and work practices associated with managing underground system, both urban and URD / UCD.
This task force meets several times per year by WebEx or in person. There is usually one in-person meeting per year held in conjunction with the other P180 task forces. The in-person meeting is normally held in either Lenox, MA, or Charlotte, NC.
Members are encouraged to participate in several ways:
- Attend task-force meetings
- Review and comment on reports and findings
- Provide materials for testing or evaluation, including new, aged or failed underground devices
- Provide information on your company’s standards or practices (a survey for example)
- Provide data for analysis, including asset and asset performance data
- Attend testing at EPRI laboratories
- Present to the task force on company issues or initiatives
This task force is also a good opportunity to meet peers at other participating companies, and collaborate to address common challenges.
Common Questions
Who can attend task-force meetings?
- Task-force meetings are for funders of the appropriate P180 project. This includes task-force members and guests from sponsoring companies.
Are there specific membership requirements?
- The only requirement is to fund P180.002, Underground Assets. Membership is rather loose. There are no meeting attendance requirements.
How do I join this task force?
- Just send a request to John Tripolitis, Josh Perkel or Eric Cornwell. Similarly, if you’d like to be removed, let one of them know.
Can my company have more than one task-force member?
- Yes.
Can I share task-force material within my company?
- Yes.
Can I share task-force material outside my company?
- Generally not. There are exceptions, so if you have a need, please contact John Tripolitis.
Are discussions covered by a non-disclosure agreement?
- Yes. All EPRI member agreements include non-disclosure clauses.
If my company isn’t funding this, how can I sign up?
- Each company has their own methods for selecting components of the annual EPRI research portfolio. If my company isn’t funding this, how can I sign up? Technical advisors from EPRI’s member services can also help. Find contact information here.
Supplemental Projects
EPRI participants can engage EPRI with supplemental projects. When a company funds EPRI annual research, 25% of the funds are set aside as self-directed funds (SDF). Utilities can use this to fund supplemental projects. Options for these projects can include:
- Field pilots of technologies
- Integration of research results
- Teardowns of failed equipment
- Test specific equipment or scenarios
New Supplemental Offering
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Underground Structure Monitoring Guiding Alarm Settings and Monitor Deployment
This project will commence in 2023, but is open to additional participants. Please view the following links for more information on the project: PDF | PPT
Supplemental projects can be one-on-one efforts, or projects can be collaborative. Companies allocate their self-directed funds in different ways. Please contact your METT for more information.
For more on supplemental projects, see here. To discuss project ideas, contact John Tripolitis.
Related Research
Collaborative Supplemental Projects
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Underground Structure Monitoring -Guiding Alarm Settings and Monitor Deployment
As underground cables and components degrade, they can generate a variety of gases from chemical reactions caused by heating, overheating, arcing, and general aging. These gases may be combustible and, should the presence of these gases not be identified, can build up and lead to an explosive event which can endanger the public, utility workers, and damage equipment. This research is expected to increase industry understanding of combustible gas behavior in underground structures to inform detection sensor placement within the structures, required sensitivities, and alarm settings. Findings from this research will enable utilities to better leverage underground structure monitoring technologies to identify precursor conditions of underground structure events, enabling them to respond and minimize or prevent these events from occurring, and increase public safety. This project will commence in 2023, but is open to additional participants. Please view the following links for more information on the project: PDF | PPT |
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Evaluating Remote Inspection Technologies for the Underground Structures
This project is aimed at providing the industry with information to: 1) understand and compare the technologies that can be leveraged to remotely ascertain conditions in UG structures, including technology for creating a visual capture of the UG distribution system, 2) explore how the information captured by different technologies can be applied and the potential benefits and limitations associated with each approach and 3) understand the potential to remove workers from hazards while still performing necessary inspection and assessment activities. |
For more on supplemental projects, see here. To discuss project ideas, please e-mail Josh Perkel or Nigel Hampton.
Implementation Opportunities
Supplemental projects can also be one-on-one efforts. Companies allocate their self-directed funds in different ways. Options for these projects can include:
- Field pilots of technologies
- Integration of research results
- Teardowns of failed equipment
- Test specific equipment or scenarios
Examples related to current research could include:
- Forensic examination of particular UG components
- Testing performance of a cable accessories in a submerged environment
Services and Capabilities
EPRI has several capabilities available to utilities as part of research work, supplemental projects, or service agreements:
- Arc-flash testing of equipment
- Forensics and material analysis of equipment failures
- Custom tests of Underground components
- Full-scale testing of UG structure events
- Evaluation of online condition monitoring equipment
Other EPRI Underground Research
EPRI research related to distribution underground assets in several other areas
TASK FORCE
P36 Underground Transmission
Underground transmission systems consist of extruded and laminar dielectric cables and accessories.
This program intends to assist utilities in resolving challenges related to design, construction, installation, operation, and maintenance of underground transmission systems. Cross-cutting research addresses issues such as design calculations, cable ratings, and inspection technologies.
Research specific to extruded dielectric cable systems focuses on cable thermo-mechanical behaviors, sensing and monitoring, and component and system aging characteristics. Research specific to laminar dielectric cable systems is concentrated on cable and system diagnostics, buried steel pipe corrosion, and failure root causes.
One project is designed to focus on principles, experiences, and knowledge capture for transmission cable engineers of utilities installing or considering underground transmission lines.
The HVDC Land and Submarine Cable Systems project addresses the emerging issue of grid integration and interconnections and long-distance transmission from remote renewable energy generation sources.
41.05.02 Plant Engineering (Nuclear Sector)
The Plant Engineering Program performs research to inform decisions related to the continued safe, reliable, and efficient operation of nuclear power plants. Research activities address key equipment issues and the effectiveness of plant engineering programs. Active and ongoing research includes but is not limited to: component aging and mitigation (flow-accelerated corrosion, electric cables, buried piping, cathodic protection, nuclear grade coatings, electric relays), system reliability (offsite power, emergency power, single point vulnerabilities), plant performance (heat exchangers, transformers, service water system, plant thermal performance), and other engineering and operational support areas (procurement engineering, seismic qualification, workforce and skills development). The program also supports technology transfer through technical assistance programs, user groups, interest groups, and training.
Program 180: Distribution Systems
Research into automated underground devices is also occurring in P180.003, Distribution Automation project.