2022 Underground Assets Project Tasks

Underground Switch Forensics: This research investigates medium-voltage underground switch life-cycle performance. The research includes analysis of new, field-aged, and damaged units, as provided by utilities, to better understand 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. Results from this research can reduce system operating costs and enhance reliability. For 2022, EPRI will issue a first edition guideline that summarizes the learnings from this body of work.

Cable Accessory Performance: This research task will investigate cable accessories, including joints, terminations, and separable connectors, to understand their life-cycle performance. The research may include forensic analysis of aged/failed units supplied by utilities, or of new units subjected to accelerated aging to expose degradation and failure modes. Research also includes longer term testing to understand equipment performance. 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.

Infrared Thermography: This task will research the use of infrared thermography for underground component diagnostics, including research aimed at informing trigger points for action. Planned activities include development of an energized test bed for examining heating in medium voltage components under different conditions.

Monitoring of Network Transformers: In 2021, EPRI completed initial testing of a single gas (H2) submersible dissolved gas analysis (DGA) monitor. In 2022, EPRI will continue to research network transformer monitoring and investigate trigger points for action associated with monitored conditions.

Underground Structure and Equipment Corrosion Mitigation : Underground structures and equipment are exposed to environmental factors that can cause corrosion, which can shorten the life of critical underground equipment and structures. For 2022, EPRI will research corrosion identification and mitigation techniques in underground equipment and vault structures and will develop guidance. EPRI will investigate the use of AI / image processing technology to assist inspectors in identifying structural deficiencies in underground structures. This task will leverage research into corrosion and corrosion mitigation performed in complementary projects at EPRI.

Underground Residential / Underground Commercial Distribution (URD / UCD) System Practices: EPRI will continue its focus on identifying, assessing, and sharing industry underground practices. For 2022, EPRI will focus its research on collecting and sharing URD / UCD practices across the industry. A workshop will be hosted to facilitate practice sharing and research prioritization in this key area of distribution. Results will be included in the EPRI Underground Practices Repository.

Urban Underground Practices : EPRI will continue to organize and facilitate the North American Dense Urban Utility Working Group.

Update to the Underground Distribution Systems Reference Book (Bronze Book): For 2022, EPRI will produce an update to the Underground Distribution Systems Reference Book.

Manhole Events: This research focuses on understanding the causes of manhole events, determining methods to identify precursors to such events, and assessing various event mitigation systems. In 2021, research included testing of new and aged low-voltage cable systems to understand the types of gases formed when cables are subjected to overheating and arcing. For 2022, EPRI will continue testing to understand gas production associated with low voltage cable systems, and research combustible gas production rates associated with selected causes, including arcing. Results could inform selection and placement of monitoring systems to identify manhole event precursors.