Relay Coordination
Study (ETAP)
Overview
A Relay Coordination Study — also known as a Protection Coordination Study — ensures that protective relays in a power system operate in the correct sequence and within the correct time intervals to isolate only the faulted section of a network while keeping the rest of the system energised. Proper relay coordination is the backbone of electrical system reliability and safety, and is mandatory for most industrial facilities, grid-connected plants, and utility networks operating under CEA regulations.
What the Relay Coordination Study (ETAP) Covers
Comprehensive protection modeling
Using ETAP's Protection & Coordination module, we model every relay, fuse, circuit breaker, and protective device in the network and determine their time-current characteristics (TCC). The study encompasses:
Full TCC Curve Development
Full time-current characteristic (TCC) curve development for all protective devices in the system
Overcurrent Relay (OCR)
Overcurrent relay (OCR) coordination: grading of IDMT and definite time relay curves across radial and meshed networks
Earth Fault Coordination
Earth fault relay coordination: sensitive earth fault (SEF), restricted earth fault (REF), and directional earth fault (DEF) settings
Differential Protection
Differential protection zone boundary definition for transformers, buses, and generators
Distance Relay Settings
Distance relay reach and time zone settings for transmission and sub-transmission lines
Fuse Coordination
Fuse-relay and fuse-fuse coordination for MV and LV distribution networks
Breaker Failure (BF)
Breaker failure (BF) protection timing verification
Utility Upstream Integration
Coordination with upstream utility protection where applicable
Applicable Engineering Standards
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IEEE C37.112 & 242
IEEE Standard Inverse-Time equations and Recommended Practice for Coordination (Buff Book)
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IEC 60255 Series
Functional requirements and performance for measuring relays and protection equipment
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CEA Regulations
Central Electricity Authority standards for protection of electrical plants and lines
Typical Applications
Relay coordination studies are required for new industrial plant construction, substation upgrades, renewable energy plant interconnection, power distribution networks in commercial complexes and data centres, and as part of periodic protection review programmes for operating utilities.
Benefits
Ensuring your system responds exactly as designed — protecting people, equipment, and uptime.
Outage Minimization
Minimises the extent of outages by ensuring only the faulted zone is isolated during a fault
Asset Protection
Protects high-value equipment — transformers, motors, generators — from damage caused by sustained fault current
Regulatory Compliance
Satisfies utility interconnection requirements and CEA regulatory obligations
Safety Optimization
Reduces arc flash incident energy at switchgear locations by enabling faster upstream clearing
Auditable Documentation
Provides a documented, auditable protection setting schedule for operations and maintenance teams
Why We Are the Best for Relay Coordination Studies in India
Relay coordination in India's industrial and utility environment presents challenges that generic software-driven studies frequently fail to address: the prevalence of aged electromechanical relays still in service alongside modern numerical relays, the lack of consistent protection documentation from original plant designers, and the need to coordinate with DISCOM upstream protection settings that are not always freely shared. Our team has navigated all of these realities on projects ranging from 11 kV distribution feeders in industrial estates to 220 kV substation protection reviews for state utilities.
We bring not just ETAP modelling capability, but real field experience of relay testing, commissioning, and fault investigation. This means our coordination studies are grounded in what is achievable in practice, not just what looks neat on a TCC curve. Where a study reveals conflicts with legacy relay characteristics, we propose pragmatic upgrade paths — not just theoretical replacements.
Full Scheme Expertise
ETAP Protection & Coordination module expertise covering overcurrent, differential, distance, and earth fault schemes
CEA Framework Alignment
Experience coordinating with DISCOM/utility protection settings under the CEA Technical Standards framework
Topology Versatility
Coordination studies for both radial and ring-main distribution topologies, including systems with generator infeed
Engineer-Ready Outputs
Relay setting schedule documentation formatted for direct use by commissioning and maintenance engineers
Integrated Safety Analysis
Integration with arc flash study: relay coordination and arc flash analysis delivered as a combined package for maximum consistency and efficiency
Ensuring your protection scheme performs exactly when needed.
