ABB REX521GHHPSH06G Low-Voltage Overcurrent Protection Relay

Description

REX521GHHPSH06G

The ABB REX521GHHPSH06G is a compact numerical overcurrent protection relay belonging to ABB’s Relion® product family, specifically designed for low-voltage distribution network protection and control. As a key component in modern electrical distribution systems, it combines essential protection functions—including overcurrent, short circuit, and earth fault protection—with basic control capabilities in a space-saving design, eliminating the need for multiple discrete protection devices in crowded distribution panels.

REX521GHHPSH06G

This relay integrates seamlessly into both traditional and modern electrical architectures, supporting simple hardwired connections alongside basic communication protocols for integration with building management systems and industrial control networks. Its intuitive configuration allows adaptation to various low-voltage applications, from motor protection circuits and distribution feeders to lighting and auxiliary power systems. What makes the ABB REX521GHHPSH06G particularly valuable is its balance of essential protection functionality and compact dimensions, making it ideal for installations where panel space is limited but reliable protection is non-negotiable.

REX521GHHPSH06G

Main features and advantages:

The ABB REX521GHHPSH06G delivers dependable protection performance through a dedicated microprocessor that executes protection algorithms with fast response times, ensuring timely fault detection and isolation. It features a comprehensive set of protection functions including inverse time overcurrent protection (according to IEC 60870-5-103 standards), instantaneous short circuit protection, and earth fault protection—critical for safeguarding low-voltage equipment and distribution circuits.

Hardware design highlights include a rugged, compact enclosure that operates reliably in temperatures ranging from -5 °C to +55° C, making it suitable for indoor distribution panels and control cabinets. The relay offers flexible connection options with terminal blocks designed for easy wiring, supporting direct connection to current transformers and control circuits. Its low power consumption and efficient design allow for Intensive installation in distribution panels without additional cooling requirements, while status LEDs provide clear visual indication of operational status and fault conditions.

REX521GHHPSH06G

Application areas:

In low-voltage distribution panels, industrial control systems, and commercial building electrical networks, reliable protection against overcurrent conditions is essential to prevent equipment damage, electrical fires, and unplanned downtime. These environments demand compact, cost-effective protection devices that can detect overloads, short circuits, and earth faults while integrating with existing control architectures. Whether safeguarding motor circuits in manufacturing facilities, protecting lighting systems in commercial buildings, or monitoring distribution feeders in data centers, engineers need solutions that deliver consistent performance in space-constrained installations.

This is where the ABB REX521GHHPSH06G excels, serving as a compact overcurrent protection relay for low-voltage distribution applications across diverse industries. In industrial plants, it protects critical motor control circuits from overload damage, ensuring production continuity. In commercial buildings, it monitors power distribution to lighting and HVAC systems, preventing circuit overloads during peak usage. Used in power system protection for years, the ABB REX521GHHPSH06G has proven its reliability in applications requiring straightforward installation, easy configuration, and dependable fault detection—making it a trusted choice for electrical contractors, facility managers, and industrial operators worldwide.

REX521GHHPSH06G

Related products:

ABB REU615 HBUAEAADANB6ANN1XG – Secondary substation relay that coordinates with the ABB REX521GHHPSH06G in hierarchical protection schemes.

ABB REF615 – Feeder protection relay often paired with the ABB REX521GHHPSH06G in industrial distribution networks.

ABB REX640 – Auxiliary control relay that enhances the ABB REX521GHHPSH06G’s control capabilities for complex interlocking.

ABB PSE600 – Compact power supply unit providing stable voltage to the ABB REX521GHHPSH06G in control panels.

ABB HMI60.1 – Local operator panel that can display status information from the ABB REX521GHHPSH06G.

ABB CMU800 – Circuit breaker monitoring unit that works with the ABB REX521GHHPSH06G to provide breaker health data.

ABB SPACOM S200 – Communication gateway enabling the ABB REX521GHHPSH06G to connect with SCADA systems when using Modbus.

ABB TCM800 – Transformer condition monitoring unit that integrates with the ABB REX521GHHPSH06G in distribution transformer applications.

REX521GHHPSH06G

Installation and maintenance:

Before installing the ABB REX521GHHPSH06G, ensure the DIN rail is securely mounted in the distribution panel with at least 30mm clearance above and below the device to facilitate wiring and heat dissipation. Verify that current transformer (CT) ratios match the relay’s input specifications and that polarity is correctly observed for accurate current measurement. The relay should be connected to a stable auxiliary power supply, with proper grounding according to local electrical codes using a 2.5mm² conductor to minimize electrical interference.

For maintenance, perform semi-annual visual inspections to check for loose connections, dust accumulation, and damage to terminal blocks. Use ABB’s configuration software annually to verify protection settings and review event logs for any recorded faults or operational anomalies. Firmware updates, when available, should be applied during scheduled maintenance periods, with configuration backups stored securely beforehand. The ABB REX521GHHPSH06G includes status LEDs that provide immediate visual indication of operational status, simplifying routine checks and troubleshooting.

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