Protection and control REX615

All-in-one protection for power generator and distribution applications

REX615 is a freely configurable all-in-one protection and control relay for power generation and distribution applications. A wide application coverage combined with a fully modular and scalable hardware and software ensures maximum flexibility and optimal cost-effectivity throughout the relay life cycle – from tailoring to adapting to changing and new application-specific requirements. REX615 represents the next step for ABB’s 615 and 620 series relays in terms of technological innovation, flexibility, cost-effectiveness and standardization. 

As part of ABB’s Relion® protection and control family of relays, REX615 builds on ABB’s strong heritage of freely configurable multifunctional relays and many proven protection algorithms.


All-in-one protection and control REX615


  • Wide application coverage with one freely configurable device for flexible and
    cost-effective tailoring to application-specific requirements
  • Ready-made application packages for convenient and smooth ordering
  • Easy and flexible adaptation to changing protection and communication requirements with fully modular hardware and software
  • Unique earth-fault protection portfolio for optimal selectivity, sensitivity and reliability – irrespective of the type of network and fault
  • The world’s first truly IEC 61850-based protection relay – designed to support the increasing digitalization of substations
  • Over 1 million 615 and 620 series relays installed worldwide – demonstrating reliability and commitment to continuous evolvement
  • Intuitive human-machine interface (HMI) with a large graphical display for showing customizable single-line diagrams (SLD)
  • Optional full conformal coating for outstanding performance also in the most extreme environments
  • Convenient, tailor-made retrofit connector kit for fast and easy replacement of SPACOM with REX615 relays


  • IEC 61850 Edition 2.1 and Edition 1, with redundancy support based on HSR and PRP
  • Ability to receive two streams of sampled measured values (SMVs) and send one via
    IEC 61850-9-2 LE-based process bus communication
  • Multifrequency admittance-based earth-fault protection (MFA) for optimal selectivity, sensitivity and reliability also in compensated and isolated networks
  • Touch voltage-based earth-fault protection for an optimal balance between safety and supply quality also in compensated networks
  • Compliance with the latest grid codes to ensure renewables remain connected during disturbances
  • Withdrawable plug-in unit design for swift installation, maintenance and testing
  • Optimal cyber security to promote secure connectivity and safeguard today’s network
  • Three lens-type arc flash light detection sensors for extended personnel safety 

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