Inquire about this publication
Project: T184700 #50/150

Assessing the condition of distribution assets – critical distribution components, in particular – is an important utility activity in maintaining or improving the reliability of overhead and underground distribution systems. Typically, asset condition assessment is accomplished via visual inspection by trained utility personnel walking/driving the line, climbing inspections (overhead systems) and visiting sites where the system is accessible, such as pad-mounted equipment and vaults (underground systems).

However, challenges with visual inspection are:

- Costly and resource-intensive (personnel, vehicles, tools) due to large service areas, including difficult-to-access areas and the need for regular assessment of critical components

- Subjectivity due to differing levels of personnel training, attitude and powers of observation

The objective of this work was to explore surveillance methods/techniques/tools – those currently available or expected to be available within the next 5 to 10 years, based on the latest research – that would allow for inspection of critical components in a cost-effective and objective manner.

Throughout the course of this project, over 60 papers, reports and standards were reviewed concerning surveillance methods, techniques and tools, failure mechanisms, thermal and partial discharge (PD) detection and image processing techniques.

A utility survey was compiled requesting information on primary distribution systems and environments, surveillance methods/techniques, tools/platforms and post-inspection processing, associated with the inspection of critical overhead and underground primary distribution system components (excluding cable).

Each critical component was considered in terms of it having current-carrying capability, voltage-withstanding capability or both, as the generic failure mechanisms are different but detectable using thermal and partial discharge (PD) methods/techniques, respectively. Using insights gleaned from the literature review and utility survey, the various surveillance methods/techniques were ranked on a scale of 0 to 10.

Application of a surveillance method/technique typically requires a tool and/or platform, e.g., IR camera and bucket truck for overhead components. Each surveillance method/technique was paired off with various possible tools/platforms and ranked on a scale of 0 to 10 in terms of tool price, inspection cost, level of accessibility to component and level of subjectivity in assessment of component condition.


Primary distribution system, critical distribution component, overhead, underground, surveillance inspection, method, technique, tool, platform