2024 Underground Assets Project Tasks

Underground Switch Automation Forensics: Utilities have begun deploying automated devices in underground systems. This research task plans to focus on the expected long-term performance of padmounted and subsurface designs, including investigation of degradation and failure modes. EPRI also plans to continue developing content for the Underground Switch Guidebook, summarizing key lessons from years of research into guidance that can improve equipment specifications, refine inspection and maintenance approaches, and reduce the likelihood of failure.

Cable and Cable Accessory Performance: This research task investigates cable and cable accessories, including joints, terminations, and separable connectors, to understand their life-cycle performance. In 2024, EPRI plans to continue its investigation of newer cables, such as lead-free EPR and EAM insulated cables, focusing on implications of material selection and exploration of diagnostic and online monitoring approaches. Also, EPRI plans to research impacts of external contamination and submergence to the expected long-term performance of cable and cable accessory materials.

Underground Distribution Transformers: Proposed efficiency standard changes and supply chain constraints may require utilities to adopt new transformer designs. In 2024, EPRI intends to document and examine emerging underground transformer options. In addition, existing transformer fleets will be exposed to new load cycle characteristics that may impact expected life. EPRI plans to investigate leading practices and technologies for extending the life of existing fleets.

Diagnostics Techniques for Underground Systems: This task researches the use of various diagnostic techniques for underground systems, including investigating trigger points for action. Planned activities for 2024 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. EPRI will also explore the efficacy of commissioning test options, such as VLF withstand testing or partial discharge testing, to identify cable accessory workmanship issues.

Online Monitoring Technologies: Utilities are beginning to deploy online monitors on underground distribution systems, such as voltage and current monitors in separable connectors, partial discharge monitors in UG structures, and transformer monitors that measure pressure, temperature, and oil level. For 2024, EPRI aims to scout online monitoring technology options for underground distribution systems. EPRI also plans to gather leading practices that leverage monitor data to manage assets. A workshop is planned to share practices and collaboratively address common issues.

Equipment Corrosion Mitigation: Underground structures and equipment are exposed to environmental factors that can cause corrosion. For 2023, EPRI began research to understand corrosion rates of commonly used underground equipment metals in submersible environments. This research will continue in 2024, including a comparison of observed field corrosion rates with selected accelerated aging corrosion rates. The goal of this research is to develop guidelines for identifying and assessing equipment in underground structures and for selecting appropriate corrosion prevention and mitigation techniques.

Underground Structure Events: This research focuses on understanding the causes of underground events that occur in manholes and vaults, determining methods to identify precursors to such events, and assessing event mitigation systems. For 2024, EPRI will test gas monitoring sensors using a novel approach EPRI developed in 2023. In addition, EPRI will continue research into detection of other non-gas-related manhole event precursors. The goal of this research is to identify tools better able to detect event precursors.

Update to the Underground Distribution Systems Reference Book (Bronze Book): For 2024, EPRI will produce an update to the Underground Distribution Systems Reference Book. Planned new content includes content on personal protective grounding in underground distribution systems.

Technology Scouting: The pace of change in distribution technology is accelerating, with new technologies, approaches, vendors, and service providers entering the market and offering new solutions. This research will scout new technologies for underground distribution and identify opportunities for further investigation and demonstrations.