Power System Protection Coordination

Proper protection coordination ensures that only the faulted portion of your electrical system is isolated during a fault, minimizing downtime and maintaining service to unaffected loads. Pythian Design provides comprehensive protection coordination studies with time-current curve analysis, relay settings, and coordination with utility protection schemes.

The Importance of Coordination

Selective Tripping: When a fault occurs, only the protective device immediately upstream of the fault should operate, leaving the rest of the system energized.

Minimize Downtime: Proper coordination limits outage extent, reducing lost production or service interruptions.

Equipment Protection: Correctly set protective devices prevent equipment damage from prolonged faults.

Safety: Coordination ensures backup protection operates if primary protection fails.

Time-Current Curve Analysis

We develop comprehensive time-current coordination (TCC) diagrams showing all protective devices.

Devices plotted include circuit breakers with relay characteristics, fuses, reclosers, and sectionalizers.

Coordination intervals verified per IEEE and industry standards (typically 0.2-0.4 seconds).

Motor contribution and distributed generation effects accounted for in fault calculations.

Utility coordination points identified and verified per utility requirements.

Standards & Compliance

• IEEE 242 (Buff Book): IEEE Recommended Practice for Protection and Coordination of Industrial and Commercial Power Systems.

• IEEE C37 Series: Relay and circuit breaker standards.

• ANSI/IEEE Standards: Device numbers and protection functions.

• Utility Protection Standards: Coordination with utility overcurrent, reclosing, and voltage protection.

What We Deliver

•Short circuit analysis providing maximum and minimum fault currents

•Time-current coordination curves (TCC diagrams) for all voltage levels

•Relay settings for all protective relays (overcurrent, ground, directional)

•Coordination tables showing time intervals between devices

•Verification of selectivity throughout the system

•Fuse selection and sizing where applicable

•Motor protection coordination

•Utility coordination verification

•Protective device settings sheets ready for field implementation

•PE-stamped report for utility and AHJ submittal

Why Choose Pythian Design

Comprehensive Analysis: We evaluate all protective devices and voltage levels for complete system coordination.

Utility Expertise: Deep understanding of utility protection philosophy and coordination requirements.

Practical Settings: Relay settings that provide protection while maintaining selectivity and minimizing nuisance tripping.

Clear Documentation: TCC diagrams and settings sheets that field technicians can easily implement.

Related Services

Substation Design Services 69kV Substations 138kV Substations 230kV Substations 345kV Substations Grounding Studies Arc Flash Studies BESS Interconnection Fire Protection Design NFPA 13 Sprinkler Design NFPA 72 Fire Alarm Design ESS Fire Protection

Ready to Start Your Project?

Request a Consultation