Target Start Date
01/2026
Anticipated Duration
12 months
Objective
Laminar dielectric cable systems consist of high-pressure fluid-filled (HPFF), high-pressure gas-filled (HPGF), and self-contained fluid-filled (SCFF) system types. These cables have generally provided long-lasting service, surpassing their design life specifications. However, the advanced age of many of these assets might be a cause for concern. Replacement costs for laminar dielectric cable systems are high, and the consequences of electrical failures or fluid leaks are significant. Research is needed to:
- Provide guidance and develop strategies for effective operation, maintenance, life extension, and replacement
- Improve understanding of laminar dielectric cable system failure mechanisms
- Develop and demonstrate inspection, diagnostic, monitoring, and remediation techniques
Underground transmission engineers, designers, and managers may use the knowledge base, guidelines, methods, and technologies developed in this project to improve productivity, lower costs of operation and maintenance, and extend the life of laminar dielectric cable systems. Reliability and safety can be enhanced, and asset management strategies can be improved. Maintenance personnel can make more effective use of staff time and budget resources by applying new inspection methods and monitoring technologies.
Planners can improve the asset fleet by identifying where to apply selective upgrades and retrofits based on a better understanding of relative system conditions. Additionally, they can determine where and under what circumstances the cable systems are most susceptible to damage. Utilities can also refine system monitoring by leveraging knowledge of component failure mechanisms, enhancing public and environmental safety.
Approach
This project investigates and develops condition assessment methods and procedures for laminar dielectric cable systems. Efforts focus on life extension, improved reliability, reduced operation and maintenance costs, and improved support for asset management decision-making protocols. EPRI intends to direct its research at one or more of the following areas:
- Evaluate and demonstrate advanced diagnostic techniques to assess conditions of laminar dielectric cables
- Develop best practices in dissolved gas analysis and insulating paper and fluid testing for effective deployment of the technologies
- Develop vintage information for laminar dielectric cable systems to improve asset management strategies
- Conduct investigations to better understand failure mechanisms of laminar dielectric cables
- Study buried steel pipe coating degradation as a function of coating types, coating ages, pipe installation environments, coating application methods, and stray current conditions
- Evaluate and develop methods to effectively detect and mitigate corrosion and corrosive environments
- Develop technical bases for best practices to improve the effectiveness of cathodic protection systems
Research Value
This research produces new understanding, methods, and tools that could improve the ability of engineers and planners to assess the condition of laminar dielectric cable systems and take proactive steps in operating and maintaining these systems to extend asset life and prevent unexpected outages. Benefits of this project may include:
- Better understanding of failure mechanisms and prevention procedures for longer asset life, fewer customer outages, and lower operations costs
- Effective inspection and monitoring of assets, leading to increased asset utilization, rapid maintenance intervention prior to spontaneous failure, higher reliability, and lower repair costs
- New inspection techniques and tools to increase staff productivity
- Reduction in overall installation, construction, operation, and maintenance costs
Anticipated Deliverables
| Deliverable | Description | Date |
|---|---|---|
| Life Evaluation and Management of Laminar Dielectric CableSystems (reports) | Volume 1: Introduction and Approach. This task describesthe EPRI general approach in life evaluation and management of laminardielectric cable systems. | December 2026 |
| Volume 2: Evaluation and Documentation of Vintage Pipe-TypeCable Performance and Experience. This task enhances the vintage guide todocument changes in component materials, design, manufacturing, and otherknown issues of pipe-type cable systems. | December 2026 | |
| Volume 3: EPRI Guide for Testing Insulating Paper andFluid. This task is a multi-year effort to create an up-to-date guide to testand analyze insulating paper and fluid of laminar dielectric cable systems toassess insulation and system conditions. This report includes results fromtests and case studies. | December 2026 | |
| Volume 4: EPRI Dissolved Gas Analysis Guide forHigh-Voltage Cables. This task continues prior EPRI research to create acomprehensive dissolved gas analysis guide to assess conditions of laminardielectric cable systems. This report also includes example test results andcase studies. | December 2026 | |
| Volume 5: Best Practices for High-Pressure Fluid-Filled(HPFF) Pipe-Type Cable Pressurization Plant Upgrades. This task providesoperating principles for HPFF cable pumping plants and a description of themany factors to consider when evaluating pumping plants for upgrades orreplacements. | December 2026 | |
| Volume 6: Pressurization Procedures for High-PressureFluid-Filled and High-Pressure Gas-Filled Cable Systems. This task describesresearch into a variety of repressurization and depressurization proceduresfor different cable constructions and offers recommendations. | December 2026 | |
| Pipe-Type CableSystem Buried Steel Pipe Corrosion (reports) | The task describes fundamentals and practices of pipe-typecable system buried steel pipe corrosion, performs various tests at EPRIcorrosion test facilities, and applies various detection techniques toinvestigate their effectiveness. The task also studies pipe coatingdegradation as a function of coating types, pipe installation environments,and stray current conditions. This task evaluates and characterizes newtechniques for condition assessment and diagnostics with emphasis ontechniques that provide localization information on potential defects ordegradation and continuous online monitoring. Techniques under investigationinclude prototype testing of test stations for buried steel pipe corrosionmonitoring. Several volumes of documents are included: 1. Introduction,Fundamentals, and Practices; 2. Pipe Test Facility and Results; 3. ExtrudedCoating Test Rig and Results; 4. Corrosion Monitoring System Development andTesting; and 5. Field Assessment Approach and Case Studies. | December 2026 |
| Failure Root CauseStudy of Laminar Dielectric Cables (reports) | EPRI has performed comprehensive research in developing anapproach for life management of cable systems, including cables,terminations, joints, pressurizing plants, and others. This task continuessuch investigations and performs further laboratory experiments to betterunderstand laminar dielectric cable aging and failure mechanisms. This taskpublishes results in separate volumes for each completed investigation. | December 2026 |
Past Example EPRI Research on Topic
| Product ID | Title | Description | Published Date |
|---|---|---|---|
| 3002029509 | EPRI Guide for Testing InsulationPaper and Fluid of Transmission Laminar Dielectric Cable Systems | A consolidated industry guide for testing and datainterpretation of fluid quality and paper tests performed on samples removedfrom aging in-service cable systems to inform and help make sound decisionson the condition and life of these assets. | 2024 |
| 3002029510 | Dissolved Gas Analysis Guide forHigh-Voltage Cables | A guide for dissolved gas analysis (DGA) sampling,analysis, and data interpretation from laboratory and field experiences. | 2024 |
| 3002029511 | EPRI Evaluation and Documentationof Vintage Pipe-Type Cable Performance Experience | A guide for cable users to record major and subtlechanges in design, materials, manufacturing, and recorded issues of keycomponents of pipe-type cable systems. | 2024 |
| 3002027224 | Utility Experience of In-PipeThermo-Mechanical Bending (TMB) Events on Pipe-Type Cables | Results to determine performance of different cableconstructions when subjected to TMB motion. | 2023 |