Release of new functionality for the all-in-one protection and control relay REX640

2023-02-20 Release announcement

We are pleased to announce the release of new functionality for REX640. ABB’s all-in-one protection relay for advanced power generation and distribution applications can now be used as a high-speed transfer device (HSTD), which continuously supervises the main feeder, automatically disconnects a failing in-coming feeder and transfers the busbar load to another feeder instead. This ensures an optimal transfer with a minimum impact on the manufacturing process and no risk of damage to the equipment – saving time and money.

The already impressive earth-fault protection portfolio is expanded by adding touch voltage-based earth-fault protection. It represents an entirely new approach to earth-fault protection as it estimates the fault current as well as calculates the resulting hazardous touch voltage at the fault location, instead of only measuring the fault current in the substation like conventional earth-fault protection does. The result is an optimal balance between safety and supply quality in compensated and isolated networks, minimizing the risk of hazardous fault conditions and unwanted customer outages. The ability of touch voltage-based earth-fault protection to fully adapt to changes in the network topology further improves safety and adds to the convenience, ensuring the network continues to remain optimally protected.

What's new?

  • High-speed bus transfer functionality (HSBT) to secure electrical supply for critical parts of a system by connecting alternative feeders on standby
  • Touch voltage-based earth-fault protection (46SNQ, 59N) for an optimal balance between safety and supply quality in compensated or isolated networks
  • IEC 61850 Edition 2.1 – certified by DNV/GL (KEMA) – to support the increasing digitalization of the grid
  • Possibility to use the REX640 HMI as a 64-channel alarm annunciator (SACO) for clear visual alarm indications and descriptive channel-specific information
  • Generator protection improvements
    • Generator shaft current leakage protection (38, 51) based on current transformer and sensor-based measurements to detect leakage current caused by the insulation of the main shaft bearing being damaged, which inevitably will result in breakdown of the bearing
    • Improvements to three-phase underexcitation protection (40)
    • Improvements to three-phase underimpedance protection (21G)
  • Thermal overload protection for rotors in asynchronous machines (49R) based on the estimated rotor slip percentage used for calculating the induced rotor current
  • Capability of the power transformer voltage regulator (90V) to manage the changing direction of the power flow in the modern grid to maintain stability
  • Monitoring of diesel generator sets running in parallel (32/40G) for identifying and disconnecting an oddly behaving diesel generator set before the fault cascades into the neighboring units and causes a complete shutdown 
  • Power swing detection (68) to prevent operation of the distance protection during power system oscillations (power swings)
  • Travel time supervision (29CM) for motor control disconnector and motor control earthing switch 

Product range

 Protection and control REX640, product connectivity level 3 (PCL3)


  • Complete 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
  • Fully modular hardware and software for maximum flexibility and easy adaption to changing protection requirements throughout the entire relay life cycle
  • Optimal situational awareness and usability with application-driven LHMI/SHMI (switchgear HMI)
  • Ready-made application-based LHMI pages – such as support for a 64-channel alarm annunciator (SACO) – saving both time and efforts
  • Savings of up to 15% on relay costs with SHMI instead of LHMI – while still maintaining full LHMI functionality on panel/bay level for optimal visibility  

Target markets

REX640 is targeted at the global market for medium-voltage protection and control applications (IEC, CN and ANSI). 

Supported languages

REX640 LHMI is available in English, Chinese, German, Swedish, Spanish, Russian, Polish, Portuguese, Italian, French, Czech and Croatian. Additional language support will be announced later. For some languages other than English, the translation of certain text strings might not be available at the time of the release of new functionality. The language packages will be updated soonest.

Release webinar

Two release webinars open to a public audience will be held on XXXday, XX March to introduce the new functionality, one at 09:00-10:00 (CET) and another at 16:00-17:00 (CET). The speaker will be Olli Rintamäki, product line manager for REX640. For more information and registration, please follow the links below:

Morning session @ 9:00-10:00 (CEST)

Afternoon session @14:00-15:00 (CEST)

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