TheABB REX521is a high-performance, multi-functional protection relay engineered for the rigorous demands of medium-voltage networks. It provides a comprehensive suite of protection, control, measurement, and supervision functions, making it an ideal choice for incoming/outgoing feeders and asynchronous motor drives.
Technical Specifications
Protection Suite:
Overcurrent (OC) and Earth Fault (EF) Protection
Directional Overcurrent (DO) Protection
Over/Under Voltage (OV/UV) Monitoring
Thermal Overload Protection specifically tuned for motors
Relay Applications:
Incoming and Outgoing Feeders
Large and medium-sized three-phase AC motors
Back-up protection for transformers and HV lines
System Compatibility:Suitable for solidly, resistively, and resonant earthed (Petersen coil) systems
Operating Voltage:24V DC, 48V DC, or 110V DC (Model dependent)
Environmental:Extreme temperature tolerance from -40°C to +70°C
Interfaces:Integrated HMI with multi-line LCD and status LEDs
Compliance:Fully compliant with IEC 60255 and IEC 61850 standards
Key Features & Engineering Advantages
Hardware Versatility:The availability of sensor-compatible versions allows for the use of Rogowski coils and resistive voltage dividers, offering linear measurement across a wider range than traditional CTs.
Rugged Reliability:Designed to operate in harsh environments, its wide temperature range and high humidity tolerance ensure stable performance in unconditioned industrial substations.
Streamlined Integration:Pre-made standard configurations significantly reduce engineering time, allowing the relay to be quickly adapted to various grid grounding philosophies and network types.
Comprehensive Supervision:Continuous self-supervision of both internal hardware and software prevents silent failures, ensuring that protection is always ready when a fault occurs.
