Unit Protection Study for a Large Industrial Coke Processing Facility
Engineering Review of Protection Philosophy for a Multi-Voltage Industrial Power System — brownfield expansion and electrical system upgrade covering transformer, generator, busbar and motor feeder protection
Power Projects was engaged to perform a Unit Protection Study for a large industrial coke processing facility as part of a brownfield expansion and electrical system upgrade.
The study focused on reviewing and validating the protection philosophy for a complex electrical distribution network supplying critical process equipment across multiple voltage levels. Unlike conventional relay coordination studies, the scope was centred on verifying unit protection schemes for major electrical assets to ensure dependable fault detection and minimise equipment damage and unnecessary outages.
The assessment was carried out using the client's ETAP simulation model, with Power Projects responsible for validating model inputs, reviewing the protection configuration, and providing engineering recommendations where required.
System Overview
The facility operates a multi-voltage industrial electrical distribution network supplying continuous-process loads.
Voltage Levels
- 33 kV distribution system
- 11 kV distribution system
- 6.6 kV switchgear
- 415 V motor control and auxiliary distribution
Electrical Assets
- Power and distribution transformers
- Diesel generator
- HV switchboards and MV switchgear
- Motor Control Centres (MCCs)
- Power Control Centres (PCCs)
- Power Distribution Boards (PDBs)
- Variable Frequency Drive (VFD) panels
- Cooling tower systems
- Coke handling equipment
- Electric locomotives and process machinery
The combination of multiple voltage levels and interconnected equipment results in a protection system requiring detailed engineering validation.
Study Scope
The study focused on validating the unit protection philosophy across major electrical assets in the facility.
Review of the client-developed ETAP simulation model
Validation of electrical system data
Unit protection study across the network
Assessment of protection philosophy
Verification of transformer protection arrangements
Review of protection coverage for critical process equipment
Preparation of a Unit Protection Study Report
Note: Network modelling was excluded from the scope, as the complete ETAP model was provided by the client.
Engineering Focus Areas
Protection of Critical Electrical Assets
The facility includes multiple high-value transformers supplying essential process systems. Protection performance is critical, as internal faults can lead to:
- Equipment damage
- Production downtime
- High replacement cost
- Operational disruption
The study focused on ensuring that protection systems correctly distinguish between internal and external faults.
Multi-Voltage Electrical System
The network operates across four voltage levels — 33 kV, 11 kV, 6.6 kV and 415 V. Each voltage level requires appropriate protection settings based on system configuration, fault levels, and equipment ratings.
Ensuring consistent protection coordination across these levels was a key aspect of the review.
Continuous Industrial Operation
The coke processing facility operates as a continuous production system. Any unnecessary trip of transformers or major feeders can impact downstream processes and lead to significant production losses.
The protection philosophy therefore required a balance between:
- Fast fault clearance
- Equipment protection
- Operational continuity
ETAP Model Validation
Before performing the protection assessment, the client-provided ETAP simulation model was reviewed to confirm:
- Equipment ratings
- Transformer configurations
- Network representation
- Protection input data
This ensured that the study was based on a consistent and validated system model.
Engineering Methodology
Model Review
- Network topology
- Transformer representation
- Equipment connectivity
- Protection modelling assumptions
Unit Protection Assessment
- Transformers
- Generator
- Busbar protection interfaces
- Motor feeders
- Auxiliary distribution systems
Technical Review
- Proper protection zoning
- Correct application of unit protection principles
- Reliable fault detection
- Selective isolation of faulty equipment
The objective was to ensure protection operated only within the defined zone and remained stable during external faults. Engineering observations and recommendations were documented where improvements were identified.
Deliverables
A comprehensive Unit Protection Study Report was prepared, including:
Study methodology
ETAP model validation summary
Protection assessment results
Engineering observations
Recommendations for system improvement
Key Outcomes
The study delivered a structured evaluation of the facility's protection philosophy, resulting in:
Validation of the ETAP model used for the study
Verification of unit protection coverage across key assets
Improved confidence in transformer protection philosophy
Identification of engineering improvement opportunities
Technical documentation supporting future protection decisions
The assessment provides a solid technical basis for enhancing protection reliability and reducing the risk of equipment damage due to internal faults.
Project Delivery
The study was completed within a three-week engineering schedule following receipt of the purchase order and complete engineering inputs.
Engineering Schedule
Complete study delivered within three weeks of purchase order and receipt of all engineering inputs
The execution workflow included:
Engineering documentation review
ETAP model validation
Unit protection assessment
Engineering review & recommendations
Final report preparation & submission
Conclusion
Unit protection is critical for safeguarding high-value electrical equipment in industrial power systems, particularly in continuous-process facilities where system reliability directly impacts production.
Through this engagement, Power Projects delivered a comprehensive engineering review of the protection philosophy, validated the client ETAP model, and assessed the effectiveness of unit protection schemes across a multi-voltage industrial network operating at:
The study provides a structured engineering foundation for future protection enhancements and supports safe, reliable, and efficient operation of the facility.