Target Start Date
01/2026
Anticipated Duration
12 months
Objective
Cost-effective and reliable underground transmission cable systems depend on sound engineering practices of design, construction, operation, and maintenance. This project develops technologies, software tools, and guides providing a technical basis for safe, reliable, and efficient underground transmission systems of both extruded and laminar dielectric cables. The project addresses the following needs to equip cable users with knowledge, methods, and tools to execute required tasks throughout the life cycle of underground cable systems:
- Methods and tools to assist in engineering designs and to determine and improve cable circuit ratings
- Advanced designs and innovative techniques to reduce construction and installation costs
- Safe and effective cable circuit and manhole inspection techniques
- Cable and accessory failure root causes
Underground transmission engineers, designers, and managers can use the tools, methods, and technologies developed in this project to more effectively plan, design, operate, and maintain their underground transmission systems. For example:
- Laboratory and investigative results can be used to improve system long-term performance and design and implement reliable and effective cable systems.
- Software tools and analytical studies can be used to validate system designs and enhance cable project planning and management, and to increase and optimize ratings of transmission circuits.
- By applying industry best practices, especially in cable system construction and installation, utilities can reduce costs in all phases of a cable project, from design and construction to operation and maintenance.
- Development and laboratory demonstration of inspection techniques can be used to improve the health and safety of personnel working with underground cable systems.
- Investigation of corrosion inspection, assessment, and remediation methods and techniques for cable components in underground vaults addresses this emerging issue and may improve the design, inspection, maintenance, and protection of these components.
- Performance and failure information and databases can be used for effective asset management.
Approach
To address industry issues and provide adequate tools and information, this project intends to evaluate and apply industry knowledge, enhance and validate existing solutions, and investigate and develop tools and technologies by undertaking key tasks in a wide variety of activities, which may include the following:
- Develop methodologies, software tools, and practices related to design, engineering, system planning, ratings, and operations of underground cable systems
- Develop pipe-type to extruded cable conversion technology, design, and construction options, including feasibility assessment, pipe bursting technology, and extruded-dielectric pipe-type cable for installation in steel pipe
- Investigate underground transmission vault inspection techniques to improve worker safety and reduce circuit outage requirements
- Analyze field-aged cables and accessories as well as failure and performance data to investigate long-term performance issues
Research Value
Design, construction, ratings, operation, and maintenance tools and methods developed through this project could help cable users:
- Make more informed decisions when planning new transmission lines
- Improve efficiency in underground cable system designs and operations
- Improve productivity and quality in underground cable system construction
- Assess conditions of existing underground transmission lines and develop fact-based maintenance and replacement strategies
- Reduce overall installation, construction, operation, and maintenance costs
Anticipated Deliverables
| Deliverable | Description | Date |
|---|---|---|
| Underground Transmission Workstation: Functional and Technical Enhancements andDevelopments and Supporting Engineering Documents (software and reports) | The Underground Transmission Workstation (UTW) is an easy-to-use tool for cable engineers to plan, design, operate, and maintain their extruded and laminar dielectriccable systems. The project team is updating and enhancing the functionality of UTW and associated EPRI research results. In addition to the software package, various supporting engineering documents are included, e.g., EMFuser’s guide, life-cycle cost procedures, electrical safety practices, HVDC cable ratings, and thermo-mechanical force calculations. | December 2026 |
| Underground Transmission Cable System Construction and Installation (reports) | Recent advances in underground transmission have led to increased demand for best practices and innovative ways to reduce construction and installation costs. This task identifies and assesses advanced designs and innovative construction/ installation techniques that would contribute to improved operation performance and reduced overall project costs. Examples of the documents include a comprehensive practices manual, quality guidelines for grouting procedures,and primer for installation of high-voltage cable in tunnels. | December 2026 |
| Pipe-Type to Extruded Dielectric Cable Conversion—Technology, Design, and Construction Options (reports) | Reports in multiple volumes include the assessment of converting existing pipe-type cables using extruded dielectric cables and existing pipe alignments. The project task evaluates available solutions, identifies leading industry practices, presents any novel ideas for design and installation of extruded cables and accessories in steel pipes, and provides guidelines and recommendations for such conversions. Examples of the documents include feasibility assessment, pipe bursting technology, and extruded-dielectric pipe-type cable method for installation in steel pipe. | December 2026 |
| Underground Transmission Vault Inspection Using Robotic Techniques (report) | To improve worker safety and reduce circuit outage requirements, this task continues the investigation of underground transmission vault inspection techniques. Concepts and prototype robotic techniques have been demonstrated in EPRI laboratories and at member utility sites. | December 2026 |
| Underground Transmission Vault Corrosion: Inspection Assessment and Remediation (report) | This task addresses common corrosion issues within underground cable joint vaults. The report discusses corrosion mechanisms within the vaults and provides inspection and assessment results on components within the vaults. It also provides remediation recommendations based on results of field inspections and laboratory testing. | December 2026 |
| Underground Cable Fault Location Reference and Application Guide (report) | This report summarizes underground cable fault location methods and provides details in application of methods for transmission cable systems. | December 2026 |
| Performance and Failure Reports for Underground Transmission Cables and Accessories (reports) | Central to effective asset management is knowledge of the failure rate of specific components based on age, family, make, model,application, and environment. This task is a multi-year effort to gather available information on underground transmission cable and accessory performance issues, and failures of both extruded and laminar dielectriccable systems. | December 2026 |
Past Example EPRI Research on Topic
| Product ID | Title | Description | Published Date |
|---|---|---|---|
| 3002030104 | Underground Transmission Workstation (UTW) | Software tool that engineers can use to plan, design, operate, and maintain their extruded and laminar dielectric cable systems. | 2024 |
| 3002029490 | Pipe-Type to XLPE Cable Conversion—Technology, Design, and Construction Options Volume 1: Feasibility Assessment of Pipe-Type Cableto Extruded Cable Conversion — 2024 Update | Results that show it is feasible to replace pipe-typecables with extruded cables while keeping the same (or even higher) powerflow capability. | 2024 |
| 3002029491 | Pipe-Type to XLPE Cable Conversion—Technology, Design,and Construction Options Volume 2: Concept Evaluation and Demonstration of Pipe Bursting for Installation of Extruded Dielectric Cables — 2024 Update | Results of evaluation of pipe bursting as a method to use existing assets to improve power transfer capability without the need to excavate major lengths of trench. | 2024 |
| 3002029493 | Pipe-Type to XLPE Cable Conversion—Technology, Design, and Construction Options Volume 4: Extruded-Dielectric Pipe-Type Cable (EPCable) for Installation in Steel Pipe — 2024 Update | Report on EPRI cable design concepts, feasibility, and technical considerations of retrofitting pipe-type cable pipes with extruded-dielectric cables. | 2024 |
| 3002029489 | Reliable Performance of Transmission Cable Accessories – Outdoor Aging Test Rig | Results of analytical and laboratory studies on extruded cable terminations with composite insulation and evaluation of service-aged components. | 2024 |
| 3002029496 | Failure and Performance Report of Underground Transmission Cables and Accessories | Documentation of information on underground transmission failures of extruded and laminar dielectric cable systems. | 2024 |
| 3002029495 | Underground Transmission Vault Inspection Using Robotic Techniques — 2024 Update | Documentation of the approach and demonstration resultsat different utility sites. | 2024 |
| 3002027202 | Underground Transmission Cable System Construction and Installation Practices Manual | Report on advanced designs and innovative construction/installation techniques that would contribute to improved operation performance and reduced overall project costs. | 2023 |