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Relay Logic Design

We design protection and control logic around your network's actual configuration — covering feeder, transformer, generator, motor, and busbar schemes — rather than adapting a generic template to your site.

What this covers

  • Feeder protection — overcurrent, earth fault, reclosing and blocking logic for radial and ring distribution networks.
  • Transformer protection — differential, restricted earth fault, thermal and tap-changer interlocking schemes.
  • Generator and motor protection — stator and rotor functions, loss of excitation, reverse power, thermal overload and locked-rotor logic.
  • Busbar protection — differential and blocked-busbar arrangements, including breaker failure and end-fault coverage.
  • Interlocking and control logic — switching sequences, synchronism check, and permissive schemes.
  • IEC 61850 GOOSE logic — publisher/subscriber mapping where a station bus replaces hardwired signalling.

What you receive

  • Protection and control logic diagrams for each protected zone
  • Relay configuration files and functional block documentation
  • GOOSE mapping tables and dataset definitions for IEC 61850 schemes
  • Signal and interlocking matrices
  • A design basis note recording the reasoning behind each scheme choice

Standards and references

Logic design references IEC 60255 for relay performance, IEC 61850 for station communications, and the applicable IEEE C37 series for scheme practice, alongside your project specification and any utility grid code that applies.

Related services

Relay Setting Calculations

Setting and coordination calculations that keep fault clearance selective, fast and reliable.

Protection Philosophy Development

The document that sets protection principles, coordination strategy and design criteria for the whole project.

ATS Circuit Design

Automatic transfer schemes for critical loads — hardwired, relay-internal or PLC-based.

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Need relay logic design scoped?

Work directly with the engineers doing the analysis — clear scoping from the first conversation.

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