Specialised protection engineering work initiated for large generator systems
- A leading electrical engineering consultant from UAE has engaged Power Projects to perform the Unit Protection Study for two 11 kV, 100 MVA generator units.
• The scope includes Generator Differential Protection (87G) and Restricted Earth Fault Protection (64REF) as per ABB relay settings template.
• This project highlights Power Projects’ capability in advanced protection engineering and generator safety studies for utilities, EPCs and industrial clients.
Table of Contents
- Project Overview
- Scope Highlights
- Differential and REF Settings Developed to Match ABB Templates
- Technical Scope and Methodology
4.1 Data Verification
4.2 Differential Protection Setting (87G)
4.3 Restricted Earth Fault Protection (64REF)
4.4 Validation with ABB Templates
4.5 Report Submission & Revisions - Timeline
- Supporting Industrial & Utility Protection Needs
- Note to Editors
- Project Overview
Power Projects has been selected to develop precise protection settings for two 11 kV, 100 MVA generator units. The assignment covers complete differential and restricted earth fault protection calculations based on ABB relay logic, settings structure and operational constraints.
The study ensures protection reliability, fast internal fault detection and stability during normal and external fault conditions. The deliverables will support commissioning, safety compliance and long-term operational reliability.
- Scope Highlights
Under this engagement, Power Projects will perform a complete unit protection study for the generator system. The study covers Generator Differential Protection (87G) and Restricted Earth Fault Protection (64REF), along with validation of generator data, CT specifications and system parameters.
The scope also includes reviewing input conditions, checking compatibility with relay logic and preparing a detailed study report. This structured review will help ensure safe operation of the 11 kV, 100 MVA generator units and improve the reliability of protection coordination across the system.
- Differential and REF Settings Developed to Match ABB Templates
Power Projects will prepare the differential and REF protection settings based on ABB’s relay configuration templates. These settings will be calculated in line with the expected operating behaviour of the generators, enabling fast and selective fault clearance during internal faults and ensuring stability under external disturbances.
The protection logic will be customised to match ABB’s operating curves, pickup criteria, sensitivity requirements and restraint characteristics. This ensures the final protection settings are practical, OEM-compliant and ready for commissioning without modification.
- Technical Scope and Methodology
Power Projects will follow a structured and transparent engineering process to complete this assignment. Each step is designed to give the client clear, accurate and validated protection settings.
4.1 Data Verification
All generator, CT, transformer and system parameters will be checked for correctness and completeness:
- Generator ratings, impedance and winding configuration
• CT ratios, knee-point voltage, class, burden and saturation limits
• Grounding method and system short-circuit levels
• Transformer parameters and interface equipment
• Any earlier design assumptions or partial settings
Any gaps will be highlighted before calculation begins.
4.2 Differential Protection Setting (87G)
The differential protection settings will be calculated by analysing internal and external fault behaviour:
- Pickup values for operating and restraining elements
• Sensitivity checks for internal winding faults
• Slope calculations for stabilising relay performance
• CT mismatch and spill current evaluation
• Ensuring complete stator winding coverage
The goal is quick clearing of internal faults and stable operation under load changes or through-faults.
4.3 Restricted Earth Fault Protection (64REF)
REF settings will be derived based on grounding configuration and system conditions:
- Pickup current calculation based on expected fault currents
• CT matching and residual current verification
• Sensitivity at low-magnitude earth faults
• Stability checks during external earth faults
• Selectivity with 87G and upstream protections
REF ensures deep sensitivity to low-level internal earth faults.
4.4 Validation with ABB Relay Templates
All settings will be entered into ABB templates for final verification:
- Parameter alignment with ABB limits and logic
• Compliance with OEM naming and ranges
• Confirming relay operability under real system conditions
• Ensuring commissioning readiness
This prevents errors during field programming and relay testing.
4.5 Report Submission and Revisions
Power Projects will provide:
- A detailed calculation report
• Setting sheets in document and Excel format
• Up to three revisions as per PO
• Online meetings for clarification
• A final approval-ready issue
- Timeline
Despite the high capacity and complexity of the system, the complete protection study will be delivered within a 4-week schedule upon receipt of the PO and full input data.
- Supporting Industrial and Utility Protection Needs
Reliable generator protection plays a major role in keeping large power systems safe and stable. Industrial plants, utilities and backup power stations depend on accurate protection settings to avoid unexpected shutdowns, equipment stress and long outages.
Even small errors in differential or REF settings can lead to nuisance tripping or failure to detect critical internal faults. Through assignments like this, Power Projects helps clients strengthen their protection systems and ensure that generators operate safely under all loading and fault conditions.
Our work supports long-term reliability, reduces operational risks and provides engineering teams with confidence in their protection schemes.
Our studies help clients:
- Improve detection of generator internal faults
• Increase system safety and reliability
• Reduce protection maloperations
• Ensure compliance with OEM requirements
• Improve commissioning readiness
• Minimise downtime and operational disruptions
• Strengthen coordination with upstream and backup protection systems
- Note to Editors
7.1 About Power Projects
Established in 2006, Power Projects provides specialised engineering services in protection studies, relay coordination, power system studies, grid compliance and detailed design engineering.
The company supports EPCs, utilities, industries and renewable developers using ETAP, DIgSILENT PowerFactory, PSCAD and PSS®E.
Website: www.powerprojectsindia.com
LinkedIn: https://www.linkedin.com/company/power-projects/