Development of an Asset Health Index for Underground Power Cable Terminations

To move beyond isolated tests and ad-hoc judgement, this paper proposes a Health Index (HI) framework for terminations that consolidates diverse condition evidence into a single, decision‑ready indicator for planning and risk management. The Health Index developed in this paper covers terminations across all cable types; outdoor & GIS (Oil-filled cables) terminations and outdoor wet/dry-type & GIS wet/dry-type (XLPE cables) terminations.

The method integrates eight condition parameters spanning observed condition, diagnostic test outcomes, operating duty, and service environment. Each parameter condition score is assigned with an expert-agreed weight reflecting its criticality in predicting failure. This paper follows a weighted geometric mean in developing the health index, limiting compensatory effects so that strength in one area cannot conceal weakness in another. Additionally, to capture deterioration trajectories rather than static snapshots, a history‑based weighting function is developed for parameters to influence according to the recency of available samples. The health index score is expressed on a bounded scale and mapped to condition bands, providing clear triggers for maintenance, refurbishment, or replacement and enabling portfolio‑level prioritisation. Case studies across different termination types show close agreement between

HI outcomes and field observations: higher scores coincide with identified issues and informed interventions, while lower scores reflect assets in good condition. Together, these features deliver a transparent, defensible pathway from field evidence to action for cable terminations across technologies and operating contexts.