Description

Application Scenarios:

Within the main electrical substation of a large chemical plant, a 6.6kV metal-clad switchgear lineup feeds power to critical reactors. A technician performing routine infrared inspection accidentally drops a tool, causing a phase-to-ground fault that erupts into a blinding, high-energy electrical arc. Temperatures instantly soar to 20,000°C, creating explosive pressure waves. The ABB REA107-AA (RLY-REA107-AAA) arc protection relay is the system’s last line of defense. Fiber-optic light sensors inside the switchgear bay detect the intense light of the arc within 1-2 milliseconds. Simultaneously, the relay’s overcurrent element detects the sudden fault current. Using a configurable “AND” logic, the REA107-AA confirms a true arc event and sends a high-speed trip signal directly to the circuit breaker’s trip coil, bypassing slower protection relays. The breaker opens in under 60 milliseconds, starving the arc of energy, containing the damage to a single compartment, and potentially saving lives. It directly addresses the catastrophic risks of arc flash, reducing incident energy and limiting damage.

Parameter:

Main Parameters	Value/Description
Product Model/Designation	REA107-AA (RLY-REA107-AAA)
Manufacturer	ABB / Hitachi Energy
Product Category	Numerical Arc Protection Relay / Arc Flash Protection System
Detection Principle	Dual-Criteria: Light Intensity (via fiber sensors) AND Overcurrent.
Operating Time (Typical)	< 5 ms (detection) + breaker time = Total clearing time < 60 ms. [Key to limiting incident energy]
Inputs	Up to 8-12 Fiber-Optic Light Sensor Channels; 3-4 Current Inputs (CTs).
Outputs	High-Speed, High-Capacity Trip Contacts; Programmable Alarm Contacts.
Power Supply	24-48 VDC / 110-240 VAC/DC (Wide range, typical for station batteries).
Communication	Optional: RS485, Ethernet (IEC 61850 GOOSE, Modbus TCP) for integration.
Logic Configurability	Flexible “AND/OR” zoning logic between sensors and current inputs.
Protection Functions	Arc Protection (Light + Current), Optional Backup Overcurrent.
Standards	IEC 60255, IEEE C37.20.7, IEC 62271-200.

Technical Principles and Innovative Values:

The REA107-AA operates on fail-safe, high-speed principles to distinguish dangerous arcs from normal transients.

Innovation Point 1: Dual-Criteria Redundant Detection Logic: The core innovation is requiring BOTH a light input AND a current input to exceed their thresholds within a tiny, configurable time window for a trip. This prevents nuisance trips from external light (e.g., a flashlight) or high-current inrush without an arc. The logic is fully programmable, allowing for complex zoning (e.g., sensor 1 AND sensor 2 OR busbar current) to precisely locate and isolate the fault.
Innovation Point 2: Fiber-Optic Sensor Network and Self-Supervision: The relay supports a network of specially designed, flexible fiber-optic light sensors installed inside the switchgear compartments. These sensors are passive, immune to EMI, and cover large areas. The REA107-AA continuously monitors the integrity of this sensor loop. A broken fiber triggers an alarm but not a trip, maintaining protection system availability while alerting to maintenance needs.
Innovation Point 3: Ultra-High-Speed Tripping and Integration: The relay’s processing and output contact operation is optimized for raw speed, with typical internal operating times below 5 milliseconds. It integrates seamlessly with modern digital substations via protocols like IEC 61850, allowing it to send and receive high-speed GOOSE messages for zone-interlocking schemes with other protection relays, enabling selective tripping to isolate only the faulted section.