ABB REX521GHHGSH51G – Advanced Feeder Protection & Control Relay

General Description

The ABB REX521GHHGSH51G is a multifunctional feeder protection and control relay designed for medium-voltage power distribution systems. It combines protection, control, measurement, and supervision capabilities into a single intelligent device, enabling reliable operation of electrical feeders in utility and industrial networks. With ABB’s proven relay technology, this model delivers high accuracy, fast response, and long-term operational stability.

Functional Highlights

Integrated feeder protection supporting both fault detection and system coordination

High-speed processing for rapid fault clearing and minimized network disturbances

Flexible logic configuration allowing customized protection and control schemes

Strong electromagnetic compatibility, suitable for electrically noisy substation environments

Compact relay design reducing panel space while maintaining full functionality

Continuous self-monitoring to ensure dependable long-term operation

Technical Characteristics

Model: REX521GHHGSH51G

Device Category: Feeder protection and control relay

Protection Functions: Phase overcurrent, earth-fault protection, time and directional logic

Measurement Capability: Real-time current and voltage monitoring

Control Functions: Circuit breaker control, alarm signaling, and interlocking

Auxiliary Supply: Wide-range AC/DC auxiliary voltage support (variant-dependent)

Communication Interfaces: Support for standard substation communication protocols

Operating Temperature Range: Approximately –25°C to +55°C

Mounting Method: Panel-mounted installation within switchgear or relay panels

Compliance: IEC protection relay standards and ABB quality requirements

Internal Structure & Design

The REX521GHHGSH51G is built using a modular internal layout to enhance reliability and serviceability:

Digital processing unit executing protection algorithms and logic operations

Input conditioning circuits ensuring precise and stable signal acquisition

Output relay section for dependable trip and alarm execution

Communication interface module enabling integration with SCADA and automation systems

Industrial enclosure providing effective shielding against dust, vibration, and EMC interference

This construction allows the relay to maintain accuracy and stability under continuous operating conditions.

Typical Application Areas

The ABB REX521GHHGSH51G is commonly applied in:

Medium-voltage feeder protection in utility substations

Industrial power distribution networks

Ring main units (RMU) and compact substations

Manufacturing plants and process industries

Infrastructure projects requiring reliable feeder automation

Retrofit projects upgrading legacy protection relays

Its adaptability makes it suitable for both centralized substations and decentralized distribution points.

Installation Recommendations

Install the relay in a clean, dry, and vibration-free panel environment.

Follow ABB wiring guidelines for CT and VT connections to ensure accurate measurements.

Provide sufficient clearance for ventilation and front-panel access.

Verify auxiliary power supply compatibility before energizing the unit.

Complete parameter configuration and logic testing prior to system commissioning.

Maintenance & Operation

Inspect terminal connections periodically to prevent loosening over time.

Keep the relay free from dust; clean using dry, non-conductive air if required.

Review event and fault records regularly to support preventive maintenance.

Back up configuration settings to simplify future replacement or system expansion.

Conduct functional testing during scheduled maintenance intervals.

Additional Information

The ABB REX521GHHGSH51G provides a balanced combination of protection accuracy, control flexibility, and system integration capability. When deployed within ABB-based distribution systems, it enhances feeder reliability, operational safety, and overall network efficiency.