2023 Underground Assets Project Tasks

Underground Switch Automation Forensics: This research area investigates medium-voltage underground switch life-cycle performance. As automated devices are increasingly being added to underground system designs, 2023 research is planned to focus on the expected long term performance of the automation associated with underground switches, including investigation of degradation and failure modes. Research results can inform equipment specifications and inspection and maintenance approaches, reducing the likelihood of failure and aiding utilities in optimizing the life-cycle performance of these devices.

Cable and Cable Accessory Performance: This research task will investigate cable and cable accessories, including joints, terminations, and separable connectors, to understand their life-cycle performance. New components will be subjected to accelerated aging in the laboratory to expose degradation and failure modes. Forensics may be performed on aged/failed units supplied by utilities. For 2023, EPRI plans to investigate cable materials which are newer to the market, such as lead free EPR and EAM insulated cables. Research plans include material analyses and exploration of new cable material behavior when subjected to traditional cable diagnostic techniques and on line monitoring. Findings can be used to inform equipment specifications, inspection and maintenance approaches, and workmanship practices, resulting in reduced system operating costs and enhanced reliability. A goal of this research is to develop visual tools for aiding field workers in the proper construction of cable accessories.

Diagnostics: This task will continue research into the use of various diagnostic techniques for underground systems and cable accessories, including research aimed at informing trigger points for action. Planned activities for 2023 include continued examination of heating in medium voltage components under different conditions to inform the use of infrared thermography, leveraging an energized test bed at EPRI’s Lenox laboratory.

Monitoring of Network Transformers: In 2022, EPRI continued a multi - year research effort to examine the performance of a single gas submersible dissolved gas monitor, with a focus on monitor efficacy when used with alternate network transformer insulating fluids. For 2023, EPRI will continue to research network transformer monitoring and investigate trigger points for action associated with monitored conditions. Research will include analysis of monitored information from network transformers to better understand relationships between dissolved gas information and other monitored attributes.

Underground Structure and Equipment Corrosion Mitigation: Underground structures and equipment are exposed to environmental factors that can cause corrosion. For 2022, EPRI began research into corrosion identification and assessment techniques for padmounted equipment, with a focus on gathering inspection findings and images from utilities and on developing guidelines. For 2023, EPRI will continue research in this area with an aim of leveraging AI / image processing technology to assist inspectors in identifying deficiencies in underground structures. In addition, EPRI will expand the focus to include investigation of below ground structure corrosion issues and remediation approaches.

UG Structure Events: This research focuses on understanding the causes of underground structure (manholes and vaults) events, determining methods to identify precursors to such events, and assessing various event mitigation systems. In 2022, EPRI completed a multiyear research project that tested new and aged low-voltage cable materials to understand the types and production rates of gases formed when cables are subjected to overheating and arcing. For 2023, EPRI will experiment with alternate sensors and placement approaches for gas monitoring informed by this research. In addition, EPRI will continue research into detection of other (non-gas) manhole event precursors. The goal of this research is improved tools for identifying event precursors.

Underground Residential / Underground Commercial Distribution (URD / UCD) System Practices: EPRI will continue its focus on identifying, assessing, and sharing industry underground practices. For 2023, EPRI will continue collecting and sharing URD / UCD practices across the industry. Results will be included in the EPRI Underground Practices Repository.