Tripping Profile Analysis of the 33 kV Feeder of Ugbowo 2 x 15 MVA, 33/11 kV Injection Substation

Abstract

This paper investigated the tripping profile of the 33 kV feeder of Ugbowo 2 x 15 MVA, 33/11 kV electric power
distribution network. The annual data of daily tripping of the 33 kV feeder from September 2019 to August 2020
were collated and collected from the Ugbowo injection substation. The daily outage of the 33 kV feeder was used
to compute the monthly and yearly tripping profile of the sub-transmission line (33 kV feeder) of the Ugbowo
injection substation. The monthly and yearly failure rate, MTTR, MTTF, MTBF, availability, unavailability, SAIFI,
SAIDI, ASAI, ASUI, etc. for the period of twelve (12) months were analyzed using the Load Point Indices (LPI)
and Microsoft Excel was used graphically to interpret the results of the tripping profile of the 33 kV feeder. The
results obtained from the analyses of the 33 kV feeder of the network showed that yearly failure rate, MTTR,
MTTF, MTBF, unavailability, availability, SAIFI, SAIDI, ASAI and ASUI were 4.32%, 6.520 h, 23.148 h, 29.668
h, 21.98%, 78.02%, 0.0358 interruptions/customer/yr, 0.2336 h/customer/yr, 78.03%, and 21.97%, respectively.
These results revealed that the performance indices of the 33 kV feeder with annual total outage frequency (SAIFI)
and percentage availability (ASAI) were a far cry from the recommended values of the internationally acceptable
standard value (IASV) of 0.01 and 99.99% respectively. This poses a threat to the reliability and availability of
electricity supply to consumers.