ABB MT-91-ARC FP A | Arc Protection Relay for Medium-Voltage Switchgear_ABB_Manufactures_Shenzhen Silk Road XY Technology Co., Ltd

Description

The ABB MT-91-ARC FP A is a specialized arc protection relay designed to detect and respond to internal arcing faults in medium-voltage (MV) switchgear, motor control centers, and transformer compartments within industrial and utility power systems. As part of ABB’s comprehensive Relion® protection portfolio—specifically aligned with the 615/620 series architecture—the ABB MT-91-ARC FP A functions as a high-speed arc flash mitigation device that significantly reduces equipment damage, personnel risk, and downtime during catastrophic electrical faults. Unlike conventional overcurrent relays that rely solely on current magnitude, the ABB MT-91-ARC FP A combines light intensity detection via fiber-optic sensors with current supervision to deliver trip decisions in under 1–4 milliseconds.

Positioned as a modular add-on or integrated component within ABB’s arc protection ecosystem, the ABB MT-91-ARC FP A is engineered for seamless integration into both new installations and retrofit projects. It supports daisy-chained fiber loops that can monitor multiple switchgear compartments using a single unit, making it cost-effective for complex electrical distribution networks. The “FP A” suffix denotes its configuration as a fiber-optic input module with auxiliary logic processing, enabling flexible coordination with upstream breakers and master relays like the REF615 or REL670. In environments where arc flash energy must be contained before it escalates—such as petrochemical plants, data centers, or mining operations—the ABB MT-91-ARC FP A serves as a critical last line of defense, aligning with NFPA 70E and IEC 62271-200 safety standards.

Technical Specifications

Parameter Name	Parameter Value
Product Model	ABB MT-91-ARC FP A
Manufacturer	ABB
Product Type	Arc Protection Relay / Fiber-Optic Arc Detection Module
Detection Principle	Light intensity (via plastic optical fiber) + optional current supervision
Number of Fiber Inputs	1 primary fiber loop input (supports daisy-chained sensors)
Trip Time	Typically 1–4 ms from arc detection to output activation
Output Contacts	2 programmable high-speed relay outputs (NO/NC configurable)
Operating Voltage	24–250 VDC or 110–240 VAC (dual-range power supply)
Communication Interface	Optional RS-485 or IEC 61850 (depending on system integration)
Operating Temperature	-25°C to +70°C
Mounting	DIN rail mount (standard 35 mm) or panel mount with adapter
Standards Compliance	IEC 60255, IEC 61000-4 (EMC), IEC 62271-200 (arc testing)

Main Features and Advantages

Ultra-fast arc flash response through optical sensing: The core innovation of the ABB MT-91-ARC FP A lies in its use of plastic optical fiber (POF) to detect the intense light emitted during an internal arc fault—often before pressure waves or thermal effects manifest. This enables trip initiation far faster than thermal or magnetic methods alone. When combined with current supervision (to prevent nuisance tripping from external light sources), the ABB MT-91-ARC FP A achieves exceptional selectivity and speed, limiting incident energy to levels that protect both equipment and personnel.

Flexible and scalable fiber-loop architecture: A single ABB MT-91-ARC FP A can monitor an entire switchgear lineup through a continuous fiber loop that passes through multiple compartments via reflective arc sensors. If an arc occurs anywhere along the loop, light scatters into the fiber, triggering the relay. This topology reduces hardware count and wiring complexity compared to point-sensor systems. The fiber is immune to electromagnetic interference—a critical advantage in high-current environments—and requires no power at the sensing point, enhancing intrinsic safety.

Seamless integration with ABB protection ecosystem: The ABB MT-91-ARC FP A is designed to work natively with ABB’s Relion relays and automation platforms. It can send trip commands directly to circuit breaker trip coils or communicate fault status to a master relay (e.g., REF615) for coordinated system-wide action. In modern digital substations, it supports IEC 61850 GOOSE messaging for sub-millisecond interlocking across Ethernet networks. This interoperability ensures that arc protection is not an isolated function but an integrated layer within a holistic safety strategy.

Robust industrial design for harsh electrical environments: Housed in a compact, metal-reinforced enclosure with conformal coating, the ABB MT-91-ARC FP A withstands high EMI, temperature swings, and humidity typical of utility substations and industrial plants. Its wide power supply range accommodates legacy DC control systems (48 V, 125 V) as well as modern AC-powered panels. Every ABB MT-91-ARC FP A undergoes rigorous arc simulation testing during manufacturing, ensuring consistent performance under real-world fault conditions.

Application Field

The ABB MT-91-ARC FP A is extensively used in industries where electrical safety and operational continuity are paramount. In oil & gas refineries and chemical plants, it protects MV motor control centers (MCCs) and distribution switchgear from arc flash events triggered by insulation degradation, contamination, or human error during maintenance. Because these facilities often operate under strict OSHA and NFPA 70E compliance regimes, the millisecond-level response of the ABB MT-91-ARC FP A helps reduce arc flash boundary distances and PPE requirements.

In mining operations—both surface and underground—the ABB MT-91-ARC FP A safeguards mobile substations and fixed switchrooms exposed to dust, moisture, and mechanical stress. Its immunity to vibration and EMI makes it ideal for environments near large drives and crushers. Similarly, in data centers and hospitals, where uninterrupted power is critical, the ABB MT-91-ARC FP A minimizes collateral damage during rare but severe internal faults, allowing faster recovery and reducing insurance liabilities.

Utilities also deploy the ABB MT-91-ARC FP A in secondary substations and renewable energy interconnection points (e.g., solar farms, wind parks) to meet grid code requirements for fault containment. By limiting arc duration, it prevents cascading failures and protects expensive transformers and cables. For aging infrastructure undergoing life extension, retrofitting with the ABB MT-91-ARC FP A offers a cost-effective path to modern safety standards without full switchgear replacement.

Installation and Maintenance

Pre-installation preparation: Before installing the ABB MT-91-ARC FP A, verify compatibility with your existing protection scheme and confirm that the fiber-optic loop length does not exceed the maximum allowed (typically 100 meters for POF). Ensure the power supply matches the unit’s dual-range input specification (e.g., 125 VDC for utility DC systems). Mount the relay on a standard 35 mm DIN rail in a dry, ventilated section of the control panel, away from high-heat sources. Route the fiber cable separately from power conductors to avoid sharp bends or crushing—minimum bend radius is 25 mm. Perform a continuity test on the fiber loop using a visible light source before final connection.

Maintenance recommendations: The ABB MT-91-ARC FP A requires minimal routine maintenance due to its solid-state design and passive fiber sensors. However, it is recommended to perform annual functional tests using ABB’s dedicated test equipment or built-in self-test features to validate light detection sensitivity and output relay operation. Inspect fiber connections for dust, cracks, or discoloration, as degraded fibers can attenuate the arc signal. If the ABB MT-91-ARC FP A has been exposed to a real arc event—even if it did not trip—it should be inspected for internal damage. Always keep a spare ABB MT-91-ARC FP A in climate-controlled storage to ensure readiness during emergencies.

ABB MT-91-ARC FP A | Arc Protection Relay for Medium-Voltage Switchgear