Product Overview

The ICS Triplex T9902 is a high-performance, 10A fast-acting replacement fuse kit engineered specifically for the Trusted™ Triple Modular Redundant (TMR) system. This critical protection component is designed for use within T9851 and T9851/2 Field Termination Assemblies (FTAs) and digital output modules. Its primary function is to provide high-speed overcurrent protection, safeguarding sensitive controller circuitry and field-side actuators from electrical faults and transient surges.

By utilizing a specialized Littelfuse SMF Omni-Block architecture, the T9902 ensures that in the event of a field loop short circuit or an over-current condition, the fuse clears the fault rapidly. This isolation prevents damage to the more expensive I/O modules and maintains the hardware fault tolerance (HFT) of the overall safety-instrumented system.

Advanced Construction and Protection Features

The T9902 is manufactured using industrial-grade materials to meet the rigorous demands of mission-critical automation environments.

• Fast-Acting Response: Precision-engineered to trip instantly upon reaching overcurrent thresholds, preventing thermal damage to backplane interconnects.

• Superior Material Integrity: Constructed with a high-grade ceramic body and aluminum alloy end-caps, providing excellent thermal stability and resistance to mechanical vibration.

• Environmental Sealing: Rated with IP67 resistance levels, ensuring the fuse remains operational and free from corrosion in high-humidity or dust-prone industrial settings.

• Broad Voltage Compatibility: Designed to support a wide range of operational voltages up to 480V AC/DC, making it versatile for various field device configurations.

• Wide Thermal Envelope: Optimized for stable performance across a temperature range of –20°C to +70°C, suitable for both indoor control rooms and remote field enclosures.

• Certified Safety Standards: Fully tested and compliant with UL, CE, and RoHS regulations, ensuring adherence to global safety and environmental protocols.

Technical Specifications

• Manufacturer: ICS Triplex (Rockwell Automation)

• Model Number: T9902

• Product Series: Trusted TMR System

• Module Type: Replacement Output/Input Fuse

• Current Rating: 10A

• Fuse Characteristic: Fast-Acting

• Mounting Type: SMF Omni-Block Compatible

• Weight: 1.26 kg (Packaged weight for kit)

• Dimensions: 3.0 x 30.2 x 26.5 cm

• Compatibility: Specifically for T9851 and T9851/2 Termination Modules

• Origin: USA

Operational Reliability in Critical Systems

In Safety Instrumented Systems (SIS) such as Emergency Shutdown (ESD) or Fire and Gas (F&G) units, the integrity of the output circuit is paramount. The T9902 replacement fuse ensures that maintenance teams can restore protection levels immediately after a field fault has been cleared. Because the Trusted system relies on precise diagnostic feedback, using the OEM-specified T9902 fuse is essential to maintain the correct impedance and response characteristics required by the module's line monitoring circuitry.

The robust design minimizes nuisance failures, while the fast-acting clearing time ensures that high-energy faults are contained locally. This contributes to a higher Mean Time Between Failures (MTBF) for the entire control system and provides operators with long-term confidence in their hardware protection strategy.