A Dual-Perspective Reliability Assessment of Distribution Feeders using System and Customer-Oriented Indices

Author

Yahaya M. Yarda, Ahmed Muhammed, A.L Amoo


Abstract

 Reliability assessment of power distribution systems typically focuses either on component performance or customer experience. However, this single-perspective approach can misguide utility investments, especially when feeders serve vastly different customer populations. This paper presents a dual-perspective assessment of six 33 KV feeders in Gombe Metropolis, computing both system-oriented (λ, MTBF, MTTR, A) and customer-oriented (SAIFI, SAIDI, CAIDI, ASAI, ASUI) indices. A composite reliability ranking is developed by normalizing SAIFI and ASAI to prioritize feeders. Results reveal wide performance variations: Doma feeder exhibits the worst system performance (A=84.8%) but maintains a moderate SAIFI (0.03) due to its large customer base (41,119 customers), while Waterworks feeder has a modest availability (92.5%) yet extremely poor SAIFI (10.42) and SAIDI (22.87 hours/year) because it serves only 3 customers. Gombe and FMC feeders consistently rank highest in both perspectives, achieving ASAI above 97%. The composite ranking identifies Waterworks feeder as the worst performer (0.24), followed by Doma feeder (0.60). The study concludes that customer-oriented indices alone can mask severe system degradation, whereas system-oriented indices alone ignore the human impact. A balanced composite score is essential for equitable resource allocation. Utilities are advised to use the composite ranking to justify infrastructure upgrades, prioritizing Doma feeder for investment due to its massive customer base despite its "good" per-customer SAIFI.



Keywords

Reliability, Reliability indices, Failure rates, SAIDI, CAIDI.



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References


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