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Project: T163700 #30/115

The rapid rate of technological advancement can cause technical and economic obsolescence, where a population of like assets may still be fully functional but no longer meet the needs of the utility or can no longer be maintained, e.g., due to a lack of spares. Such a population of like assets is said to have reached its end-of-useful-life (EUL), even if it has not yet reached its end-of-life (EOL). Utilities require the means to predict when EUL will be reached, such that they can plan/budget ahead to replace or refurbish the population. In these cases, knowledge of EOL on its own is simply not useful.

The objective of this work was to provide utilities with a high-level guideline for the general assessment of EUL of Bay-Level substation automation assets. This will aid utilities in their decision-making process with regards to the replacement and/or refurbishment of substation secondary equipment such that the life cycle of substation automation systems will be managed in a more effective manner.

Throughout the course of this project, over 40 papers, reports and standards were reviewed on the subjects of substation automation systems, industry practices, life-cycle concepts, lifetime of equipment, reliability concepts, physical lifetime of power system, and factors affecting useful life.

A generic technique was developed that allows a utility to compute the EUL for a population of like devices based on its EOL – either known for the asset or generally applied to the asset class – and a factor score-card that the utility completes. The technique depends on multi-utility input (i.e., ranking of the importance of the factors to weight the individual utility factor scores), for which multi-utility input was obtained via a utility survey. EOL data per asset class was also collected via the utility survey and combined with an industry review of EOL.


Substation secondary equipment, relay, meter, end-of-life (EOL), end-of-useful-life (EUL), obsolescence, quantitative, qualitative, ranking, score, correction index