P36.002: Extruded Dielectric Cable Systems
Target Start Date
01/2026
Anticipated Duration
12 months
Objective
Utilities rely on extruded dielectric cable systems to meet growing demands for new underground transmission lines. This project intends to address several key research issues, including specific goals of:
- Improving engineering-based design and installation procedures to accommodate electrical, mechanical, and thermal requirements for long-term performance, considering thermo-mechanical behaviors of cables and accessories as well as corrosive environments of buried or in-manhole components
- Achieving better understanding of cable and component aging, failure mechanisms, and end-of-life criteria
- Developing effective inspection and monitoring methods for cable system condition assessment
Underground transmission engineers, designers, and managers can use the guidelines, methods, and technologies developed or assessed in this project to improve productivity and reduce costs of designing, installing, commissioning, testing, operating, and maintaining extruded dielectric cable systems. Engineers may use the improved understanding of the behavior of extruded dielectric cables under normal and emergency loading scenarios plus analytical or software-based tools to achieve effective and economical system designs. Operators and maintenance departments can deploy new inspection and monitoring methods and tools to obtain real-time and near real-time information on cable system conditions.
Approach
This project investigates methods and technologies for extruded dielectric transmission cable systems. Solutions are applicable to design, selection, installation, commissioning, testing, operation, and maintenance of these systems. The project seeks to answer research questions and address industry issues through the following activities:
- Laboratory testing to validate engineering design models
- Laboratory testing to understand failure mechanisms and end of life
- Development and evaluation of innovative inspection and assessment tools, methods, and technologies
- Laboratory testing and field demonstration of developed or available diagnostic methods
Research Value
The new materials, devices, and methods produced in this project could improve the performance of extruded dielectric transmission cable systems to meet power system safety, reliability, and maintainability requirements and to contribute to improved technical standards. For example:
- Full-scale laboratory testing may validate and improve theoretical understanding of the thermo-mechanical behavior of extruded dielectric transmission cables. The results would support improved specifications and standardized designs, leading to higher system reliability, fewer circuit outages, and lower life-cycle costs.
- Laboratory testing can deepen the industry’s understanding of cable and accessory performance and help determine the end-of-life criteria of the system.
- Development and deployment of advanced inspection and monitoring techniques may assist in asset management, improve utility operation efficiency, and increase system reliability.
- Assess conditions of existing underground transmission lines and develop fact-based maintenance and replacement strategies to reduce costs and improve reliability.
- Reduce overall installation, construction, operation, and maintenance costs.
Anticipated Deliverables
| Deliverable | Description | Date |
|---|---|---|
| Guidelines for Thermo-Mechanical Design of Extruded Dielectric Cable Systems in Pipes and Ducts (reports) | This multi-year task builds on and continues EPRI’s research in laboratory verification of thermo-mechanical behavior of extruded dielectric cables in ducts, pipes, and manholes. Reports in multiple volumes include developments of a validated source of practical engineering knowledge to assist cable engineers in designing extruded dielectric cable systems with respect to their thermo-mechanical effects. The reports cover design principles, cable mechanical parameter measurements, finite element analysis modeling, engineering software tools, full-scale laboratory validation, applications at utility sites, and subject matter training. | December 2026 |
| Life Evaluation and Management of Extruded Dielectric Cable Systems and Components (reports) | Volume 1 – Composite Cable Termination Long-Term Aging Tests:
Built on prior EPRI research, this multi-year effort continues to investigate the reliability of transmission extruded dielectric cable accessories. Included are technical and investigative results from accelerated aging tests at EPRI’s Lenox laboratory on terminations with composite insulating housing, material deterioration test results on field-aged cable terminations, and results from demonstrations of condition assessment tools.
Volume 2 – Cable Mechanical Bending Aging Tests & Volume 3 – Cable Thermo-Mechanical Aging Tests: Many extruded dielectric cable circuits are approaching 30–40 years in service. The industry needs an approach to study their life management and expectancy. This task starts as a series of laboratory experiments to better understand extruded dielectric cable system aging and failure mechanisms and has since expanded into three different tests: • Mechanical bending aging tests (30,000 to 60,000 cycles) • Full-scale thermo-mechanical aging tests (65, 80, 90, and 105 °C) • Outdoor accelerated aging tests (138-kV and load currents) The aging tests are to include both land and submarine cables as well as accessories of different designs at different transmission voltage levels. Volume 4 - Asset Vintage Guide and Technology Review: How an asset degrades and fails is often dependent on how the asset was designed and manufactured. This task develops and updates vintage information for component materials, design, manufacturing, and other known issues of extruded dielectric cable systems. This task also provides a state-of-art technology review to assist utility cable users in making engineering decisions for reliable and cost-effective in-service operations. The report captures evolving technologies, success and failure experiences, and lessons learned to enforce the needs for continuous vigilance during design, manufacturing, and installation processes of both cables and accessories. |
December 2026 |
| EPRI Guide on Extruded Transmission Cable System Condition Monitoring and Diagnostics (report) | This multi-year task is a continuation of study on advanced monitoring techniques for inspection of cable system condition and operational status. The task covers developments of test rigs and performs tests to evaluate the effectiveness of available technologies and to demonstrate emerging technologies. | December 2026 |
Past Example EPRI Research on Topic
| Product ID | Title | Description | Published Date |
|---|---|---|---|
| 3002029498 | Guidelines for Thermo-MechanicalDesign of Extruded Dielectric Cable Systems in Pipes and Ducts Volume 2:Fundamentals | Describes fundamentals in thermo-mechanical behaviorsthat determine performance of XLPE cable systems, provides design values of thelimiting parameters and an application guide for the design of duct-manholesystems. | 2024 |
| 3002029499 | Guidelines for Thermo-MechanicalDesign of Extruded Dielectric Cable Systems in Pipes and Ducts Volume 3:Mechanical Parameter Tests | Describes mechanical parameter test procedures andresults on different cable types, including samples of a 3000-kcmil copperconductor cable with corrugated copper sheath and a 5000-kcmil copperconductor cable with a copper laminate sheath. | 2024 |
| 3002029500 | Guidelines for Thermo-MechanicalDesign of Extruded Dielectric Cable Systems in Pipes and Ducts Volume 4:Finite Element Analyses | Provides results of finite element analysis modeling ofcables of different metallic sheath designs based on mechanical parameters ofaxial stiffness (EA) and bending stiffness (EI) as extrapolated from previousEPRI measurements. | 2024 |
| 3002029501 | Guidelines for Thermo-MechanicalDesign of Extruded Dielectric Cable Systems in Pipes and Ducts Volume 5:Full-Scale Experimental Verification Tests | Shows results of full-scale verification tests for EPRIthermo-mechanical models of cross-linked polyethylene (XLPE) cable in pipesand ducts. Cable constructions include 345 kV, 4000 kcmil conductor withcorrugated aluminum sheath, and 230 kV, 3000 kcmil conductor with corrugatedcopper sheath. | 2024 |
| 3002029504 | Aging Characteristics of ExtrudedDielectric Cable Systems and Components—Mechanical Bending Tests | Describes efforts in developing an EPRI bending rig and reportsresults of performed tests. This test rig determines aging performance bymechanical bending of extruded dielectric transmission cables. | 2024 |
| 3002029506 | Asset Vintage Guide andTechnology Review for Extruded Dielectric Cables, Terminations, and Joints | Provides a document to capture changes in componentmaterials, design, manufacturing, and other known issues through life cycleof cable systems in terms of design, procurement, installation, operation,maintenance, and end of life. | 2024 |
| 3002029505 | EPRI Guide on ExtrudedTransmission Cable System Condition Monitoring and Diagnostics | Documents development of EPRI Guide on ExtrudedTransmission Cable System Condition Monitoring and Diagnostics, addressing distributedtemperature sensing, field partial discharge measurements, and EPRI evaluationof monitoring technologies. | 2024 |