Short-circuit analysis and protection coordination of a 33 kV phosphate plant distribution network

Cheikhani Abdel Kader (University of Nouakchott)
Bamba El Heiba (University of Nouakchott)
Mohamed El Mamy Mohamed Mahmoud (University of Nouakchott)
Beibah Gleigume (University of Nouakchott)
Abdel Kader Mahmoud (University of Nouakchott)

International Journal of Power Electronics and Drive Systems (IJPEDS)
Vol 17, No 3: September 2026

This study presents a short-circuit and protection coordination analysis of a 33 kV/0.4 kV industrial distribution network supplying a phosphate processing plant in Mauritania. Using ETAP software, the system was modeled to evaluate fault behaviors based on IEC 60909 and IEC 60255-151 standards. The study assesses the existing protection architecture and proposes an optimized digital protection framework. Simulation results indicate that the initial symmetrical short-circuit current at the 0.4 kV busbar reaches 96.5 kA, exceeding the 25-36 kA breaking capacity of the legacy equipment by nearly 300%. The analysis also investigates single-line-to-ground faults, revealing a fault current inversion phenomenon driven by the solid grounding configuration. To address these vulnerabilities, the study proposes upgrading to 150 kA-rated high-breaking-capacity switchgear and implementing advanced negative-sequence protection (ANSI 46) and transformer differential protection (ANSI 87T). This work provides a practical diagnostic framework for mitigating asymmetrical faults and optimizing protection coordination in heavy-duty industrial clusters.