ABB REA107-AA Arc Protection Relay – REA Series

ABB REA107-AA: Single-Input Optical Arc Protection Relay for Medium-Voltage Switchgear

Arc flash events in medium-voltage (MV) switchgear are among the most destructive fault conditions in industrial power distribution. Plasma temperatures can exceed 19,000 °C within the first millisecond, generating pressure waves that rupture enclosures, destroy busbars, and create lethal shrapnel. Conventional overcurrent protection — even with high-set instantaneous elements — operates in the 20–100 ms range, a window wide enough for arc energy to cause catastrophic damage. The ABB REA107-AA addresses this gap through dedicated optical arc detection, achieving trip initiation in under 1 ms from fault inception.

The REA107-AA is a compact, single-sensor-input arc protection relay within ABB’s REA Series — a product family purpose-built for arc flash mitigation in MV switchgear, ring main units (RMUs), and secondary distribution panels. Unlike general-purpose protection IEDs that treat arc flash as a secondary function, the REA107-AA’s entire hardware architecture is optimized for one task: detecting the characteristic light signature of an arc fault and issuing a trip command before the fault energy escalates beyond containment.

The relay accepts input from one optical arc sensor — either a point sensor positioned within a specific busbar compartment or a loop sensor covering an extended cable zone. When the sensor detects light intensity above the detection threshold, the relay evaluates the signal against its configured logic (light-only or light-plus-current supervision) and energizes the trip output relay. The total operate time from arc ignition to trip contact closure is typically below 5 ms, including sensor response, relay processing, and output switching — a figure that reduces arc flash incident energy by an order of magnitude compared to overcurrent-only schemes.

The REA107-AA is deployed globally in utility distribution substations, industrial MV switchrooms, data center intake substations, offshore platform switchboards, and wind farm collector systems. Its compact DIN-rail form factor allows retrofit installation in existing panels without structural modification, making it a practical solution for upgrading legacy switchgear to current arc flash safety standards.

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Technical Parameters

Hardware Logical Analysis

The REA107-AA’s detection chain is built around a photoelectric transducer that converts incident light intensity into an analog voltage signal. This signal is fed into a threshold comparator circuit with a fixed detection level calibrated to discriminate arc flash luminance — typically in the range of several thousand lux — from ambient lighting conditions. The comparator output drives a solid-state switching stage that energizes the output relay coil without passing through a microprocessor execution cycle, which is the primary reason the relay achieves sub-millisecond operate times. There is no firmware loop latency in the detection path.

When current supervision is enabled, a separate current transformer (CT) input feeds a fast-acting current measurement circuit. The relay applies an AND logic gate: the trip output is armed only when both the light threshold and the current threshold are simultaneously exceeded. This dual-criteria architecture eliminates nuisance trips caused by maintenance flashlights, welding arcs in adjacent areas, or photoelectric sensor degradation. The current measurement circuit uses a half-cycle RMS algorithm, adding approximately 8–10 ms to the total operate time in supervised mode — a trade-off that is acceptable in most applications where nuisance trip prevention is prioritized.

The output relay contact is a heavy-duty, silver-alloy NO contact rated for the inductive load of circuit breaker trip coils. The contact is self-monitoring via a continuity supervision circuit that generates an alarm if the trip circuit becomes open-circuited — a critical feature for protection systems where an undetected wiring fault could render the arc protection inoperative. The relay’s power supply section incorporates a wide-range SMPS input stage with transient suppression, providing immunity to the voltage spikes and conducted interference common in MV switchroom environments. EMC performance is validated to IEC 61000-4 series immunity levels, including 4 kV fast transient burst (IEC 61000-4-4) and 2 kV surge (IEC 61000-4-5).

System Integration Benefits

• Sub-millisecond trip initiation reduces arc flash incident energy by up to 90% compared to overcurrent-only protection, directly lowering the required PPE category for maintenance personnel under NFPA 70E and IEC 61482-1-2.
• Standalone operation without communication dependency — the REA107-AA does not require a functioning SCADA link, IEC 61850 GOOSE message, or substation automation system to execute a trip. The protection function is entirely self-contained in hardware logic.
• Retrofit compatibility with existing switchgear: the compact DIN-rail form factor and standard relay output interface allow installation in panels originally designed without arc protection, without modifying the primary circuit or busbar arrangement.
• Dual-mode detection logic (light-only or light-plus-current) allows the protection engineer to optimize the relay’s sensitivity versus selectivity trade-off based on the specific switchgear environment and operational risk profile.
• Trip circuit supervision provides continuous monitoring of the breaker trip coil circuit, generating an alarm on loss of continuity. This ensures the protection system’s integrity is maintained between maintenance intervals and satisfies IEC 60255-121 supervision requirements.
• Deterministic hardware response eliminates the timing uncertainty inherent in software-based protection functions. The operate time is a fixed hardware characteristic, not subject to processor load, firmware version, or communication bus congestion.
• Zone-selective arc protection when combined with ABB’s multi-sensor REA Series relays: the REA107-AA can be integrated into a coordinated arc protection scheme where each zone has its own dedicated relay, enabling selective tripping of only the faulted section while maintaining supply to healthy zones.
• Diagnostic transparency via LED indicators for power supply status, sensor input status, trip output status, and alarm output status — providing immediate visual confirmation of relay state during commissioning and routine inspection without requiring test equipment.
• Reduced arc flash hazard category in formal arc flash risk assessments (per IEEE 1584-2018): the documented operate time of the REA107-AA can be entered as the protection clearing time in incident energy calculations, typically reducing the calculated incident energy at the working distance to below 4 cal/cm² — the threshold for Category 1 PPE.

Quality Assurance & Global Logistics

Every ABB REA107-AA unit supplied by siemensplc.com is sourced from verified supply channels with full part traceability. Prior to dispatch, each unit undergoes a structured inspection protocol: label and serial number verification against ABB’s part numbering conventions, physical housing inspection for signs of repackaging or counterfeiting, connector and terminal completeness check, and functional power-on verification where test equipment permits. Units are packaged in anti-static bags with moisture-barrier outer packaging and polyethylene foam cushioning rated for international air freight handling.

Shipments originate from our warehouse in Xiamen, China — a major logistics hub with direct access to international express carriers including DHL, FedEx, UPS, and TNT. Standard delivery times are 3–7 business days to most destinations in Europe, North America, Southeast Asia, and the Middle East. Expedited next-flight-out options are available for urgent plant maintenance requirements. All shipments include a commercial invoice with accurate HS code classification, a packing list, and our 12-month warranty certificate. Export documentation for controlled-destination countries is handled in compliance with Chinese export regulations and destination country import requirements.

Contact Information

Email: [email protected]
WhatsApp: +86 18359268345
Web: siemensplc.com
Location: Xiamen, China
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