TITLE:
Relay Record Interpretation and Conditional Fault Resistance Assessment in the Lamadji 90/15 kV Substation
AUTHORS:
Haroun Abba Labane, Rodrique Armel Patrick Okemba, Eyandzi Amos Omboua, Djibrine Saleh Mahamat, Abdelkhaleh Benkhedher, Alpaslan Demirci
KEYWORDS:
Digital Protection Relay, Fault Diagnosis, Fault Resistance, Grounding Reactor, NEPLAN, Power-System Protection, Substation
JOURNAL NAME:
Journal of Power and Energy Engineering,
Vol.14 No.11,
October
30,
2026
ABSTRACT: This study examines an evolving disturbance on the T100B feeder at the Lamadji 90/15 kV substation using relay-display screenshots and previously tabulated NEPLAN short-circuit results. Visual inspection suggests an initial phase-A-to-ground fault, followed by an A-C-to-ground stage and a three-phase stage, with recurrence after an apparent reclosing operation. This chronology is provisional: raw COMTRADE samples, verified CT/VT ratios, and breaker-status records were not supplied. Reported peak currents of 1.5 and 5 kA give approximate RMS estimates of 1.06 and 3.54 kA only under a sinusoidal assumption. The closest three-phase current among six tested nodes is 3.83 kA at JDB15, with an 8.19% discrepancy using the rounded RMS estimate. At that assumed location, the tested A-G resistance of 7 Ω produces 1.072 kA, with a 1.13% discrepancy. These are amplitude agreements used for case selection, not independent validation. The proposed signal-processing and classification equations are retained as an unevaluated framework. The available scalar currents cannot uniquely separate fault resistance from distance, establish the feeder measurement equivalent of a busbar fault, or explain the reported general outage. The study therefore reports a conditional resistance candidate and specifies the data needed for quantitative validation.