Reliability Assessment of 11kV Distribution Feeders: A Case Study of Ahmadu Bello University Injection Substation Zaria

The reliability assessment performance of the 11kV distribution feeders of Ahmadu Bello University Zaria was carried out in this study. The daily outages data of the feeders for the period of twelve (12) months (January 2018 to December 2018) were collected and used to compute the reliability indices for the feeders. The data collected were analysed to estimate the reliability of the injection substation for a period of twelve months. The most important reliability indices like mean time to repair (MTTR), mean time to failure (MTTF), mean time between failure (MTBF), repair rate (μ), failure rate (λ) have been determined. State probabilities for each of the unit are also calculated and finally reliability and availability of 11kV of ABU injection Station was evaluated. The results obtained from the analysis of the 11kV feeders for the period understudy (2018) show that electricity supply was at least reliable with overall availability of 90.16% of the system working without failure but not within the standard bench mark of the system network reliability. The reliability of the network 11kV feeder is below expectation, 72.55%.