ICS Triplex T8891 SOFTA | Trusted TMR Speed Output

Product Overview

The ICS Triplex T8891 Speed Output Field Terminal Assy (SOFTA) bridges the Trusted TMR controller with high-power field actuators. It delivers reliable speed control and overspeed protection for gas turbines and reciprocating compressors. This FTA conditions output signals with high noise immunity, ensuring precise actuator response in critical rotating machinery.

Technical Configuration

The T8891 operates exclusively with the T8442 power supply, which provides dual 24Vdc feeds commoned via diodes on the assembly. Each of the 40 output channels receives fused field power through a 50mA fuse, limiting loop current and protecting downstream devices. The SmartSlot connection (SK1) enables "one-to-many" hot replacement of I/O modules without system interruption. For SmartSlot Version 2 systems, the SK2 connector remains unused.

Field wiring terminates via screw-clamp terminal blocks: 12-off 3-way blocks and 2-off 2-way blocks, supporting 30 to 12 AWG (0.05 to 2.5 mm²) wire with a torque spec of 0.5 N.m. A green LED provides visual indication of field power integrity.

Technical Specifications

Installation Guide

Mount the T8891 on standard DIN rail (35mm) inside a controlled enclosure. Maintain a minimum 50mm clearance above and below the assembly for airflow. Use shielded twisted-pair cables for field wiring, and ground the shield at the field device end only. Tighten screw terminals to exactly 0.5 N.m – over-torquing may damage the clamp mechanism. Connect dual 24Vdc feeds to the 5-way PWR TB, observing polarity per the silkscreen legend. Allow 10cm service loop for each field wire to facilitate future re-termination.

Engineering Advantages

The T8891 withstands harsh industrial environments with an extended operating temperature range of -40°C to +70°C. Its fused-per-channel design prevents a single field fault from taking down the entire bank. The screw-clamp termination provides vibration-resistant connections, critical for turbine skid installations. Seamless integration with Trusted TMR architecture ensures 2-out-of-3 voting for output commands, delivering the highest SIL rating for safety-related speed control loops.

Technical FAQs

Q1: What is the function of the SmartSlot connector SK1?
A1: SK1 carries SmartSlot Version 1 signals between the T8891 and the Trusted TMR module, enabling hot replacement of I/O modules without powering down the system. This allows one FTA to support multiple modules in a "one-to-many" configuration.

Q2: Can I use this FTA with a T8442 supply that has only one active feed?
A2: Yes. The T8891 diodes common the dual feeds, so the assembly continues to operate with a single active 24Vdc feed. However, for full redundancy, connect both feeds. The green LED illuminates when at least one feed is present.

Q3: What wire type is recommended for 120Vac outputs?
A3: Use 600V-rated, 90°C minimum stranded copper wire. For 3A loads, 18 AWG is sufficient, but 16 AWG provides additional mechanical strength. Always verify local electrical codes for final installation.