Protection Coordination
Protection coordination studies are essential to establish selectivity, sensitivity, and speed across electrical distribution, transmission, and generation systems. MEPCO reviews and calculates settings for numerical protection relays, molded case circuit breakers (MCCB), air circuit breakers (ACB), and fuses to isolate faults quickly while maintaining supply to unaffected circuits.
Figure 1: Secondary injection testing and numerical protection relay calibration by MEPCO engineers.
Technical Scope & Engineering Capabilities
MEPCO Engineering Projects brings specialized domain knowledge, rigorous modeling standards, and practical site experience to every assignment. Our scope covers:
- Relay Setting Calculations: Setting calculations for overcurrent (50/51, 50N/51N), directional overcurrent (67/67N), differential protection (87T, 87G, 87B, 87L), distance protection (21), under/over-voltage (27/59), and under/over-frequency (81U/81O).
- Time-Current Characteristic (TCC) Curves: Generating coordinated TCC curves showing discrimination margins between upstream and downstream protective devices.
- Selectivity & Coordination Margins: Verifying coordination time intervals (CTI) between circuit breakers, relays, and upstream utility supply to prevent nuisance tripping.
- Instrument Transformer Sizing: Verifying Current Transformer (CT) knee-point voltage, burden, and saturation margins to ensure relay accuracy under maximum symmetrical and asymmetrical fault currents.
- Motor & Transformer Damage Curves: Plotting transformer thermal/mechanical damage curves (ANSI/IEEE C57.109) and motor thermal withstand curves against protection curves.
Software Platforms & Computational Tools
Primary Tool: ETAP Star (Protective Device Coordination & Selectivity module).
Relay Firmware Tools: Manufacturer setting tools (DIGSI for Siemens, Acselerator for SEL, Micom S1 Studio for Schneider/Alstom).
Applicable Standards & Grid Codes
Coordination Guides: IEEE 242 (Buff Book – Protection and Coordination of Industrial and Commercial Power Systems).
Relay Standards: IEC 60255 series, IEEE C37.90, IEEE C37.91 (Transformer Protection), IEEE C37.96 (Motor Protection), IEEE C37.102 (Generator Protection).
Methodology & Project Delivery Workflow
Our engineering delivery aligns with MEPCO’s structured 6-stage project execution framework, ensuring quality throughout input verification, design modeling, and client handover:
- Stage 01 — Scope & Criteria Definition: Establish study boundaries, utility tie-in data, single-line diagrams, and client objectives.
- Stage 02 — Data Audit & Modeling Assumptions: Collect, verify, and validate manufacturer datasheets, impedance tolerances, and site operating configurations.
- Stage 03 — Simulation Model Development: Build detailed, validated mathematical digital models in specialized power software.
- Stage 04 — Computational Analysis & Verification: Execute base-case and contingency scenarios, conducting rigorous internal peer reviews.
- Stage 05 — Client Review & Approval: Present study findings, address technical comments, and participate in technical clarification sessions.
- Stage 06 — Final Handover: Deliver formal certified engineering reports, executive summaries, and native simulation model files.
Figure 2: Numerical protection relay cubicles integrated into medium-voltage switchgear.
Completed Project References (From MEPCO Profile)
Selected project assignments delivered by MEPCO demonstrating our technical execution and regional client trust:
| Project Name | Client / Authority | Location | Tools / Mode | Scope Executed |
|---|---|---|---|---|
| Air Liquide Industrial Plant | Air Liquide | Egypt | ETAP Star | Relay Setting and Coordination; Load Flow & Short Circuit; Motor Starting; Arc Flash Analysis. |
| SWRO 132/13.8 kV GIS Substation, SHUQAIQ Phase 1 | Saline Water Conversion Corporation (SWCC) | Saudi Arabia | ETAP | Protection Relay Setting and Coordination Study for desalination plant high-voltage GIS substation. |
| Triomada & GPIL Plants | TAHWEEL Holding Company | Saudi Arabia | ETAP Star | Relay Setting and Selectivity Coordination; Short Circuit Studies; Arc Flash Mitigation. |
| Lekela 250 MW Wind Farm Project | EETC, Egypt | Egypt | ETAP | Substation & Collector Network Relay Setting and Discrimination Coordination. |
| Layyah Combined Cycle Power Plant | Sharjah Electricity & Water Authority (SEWA) | UAE | ETAP | Generator, Transformer, and Auxiliary Distribution Relay Setting and Coordination. |
Key Engineering Deliverables & Outputs:
- Protective Relay Setting Schedule documenting pickup currents, time dial/multiplier settings, characteristic curves, and instantaneous thresholds.
- Time-Current Characteristic (TCC) Coordination Curves plotted across all voltage levels.
- CT Sizing and Saturation Calculation Sheets demonstrating compliance with ANSI/IEC burden requirements.
- Logic Tripping Matrices and Interlocking Schematics.
- Native ETAP Star study model file.
Inquire About This Service
Contact MEPCO’s engineering team for technical proposals, study scope definition, or project consultations:
Email: m.khaled@mepco-tds.com | Phone: +20 11 2696 7082 | HQ: 5 Al-Ibrahimia Street, Cairo, Egypt