ICS TRIPLEX T8451 24Vdc Digital Output Module

Product Information

The ICS TRIPLEX T8451 is a Rockwell Automation Trusted‑series Triple‑Modular Redundant (TMR) 24 V DC digital output module. This single module integrates 40 safety output channels and is purpose‑built for the Trusted™ TMR safety‑instrumented system, complying with IEC 61508 SIL 3 safety‑level requirements.

data sheet:

T8451.pdf

Technical Parameters

Electrical Parameters

Total Output Channels: 40‑channel TMR redundant outputs

Power Supply Groups: 5 groups of isolated independent power supplies, 8 outputs per group

Optocoupler Isolation Withstand Voltage: Continuous 250 V DC, transient withstand 2500 V DC

Field Power Supply Measurement Range: 0‑36 V DC, absolute withstand range: ‑1‑60 V DC

Continuous Output Current per Channel: 2 A

Off‑state Output Leakage Resistance: 33 kΩ

Full‑load Power Consumption per Channel (1 A condition): 24 W

Output Switching Delay: 0.5 ms

Internal Module Self‑test Cycle: 2 minutes

Short‑circuit Protection: Full‑channel automatic overcurrent protection, no fuses required

Intrinsically Safe Compatibility: External safety isolators are required

Circuit Architecture: Full triple‑modular redundant fault‑tolerant design; optional per‑channel line monitoring

Mechanical Parameters

Overall Dimensions (H × W × D): 241 mm × 30 mm × 300 mm; Unit Weight: 1.13 kg

Environmental Parameters

Operating Temperature: ‑5 ℃ ~ 60 ℃

Operating Humidity: 5%‑95% non‑condensing

Vibration Resistance: 10‑57 Hz ±0.075 mm; 57‑150 Hz 1.0 g

Shock Resistance: 15 g, half‑sine waveform, duration 11 ms

EMC Performance: Air‑gap ESD 15 kV, contact ESD 8 kV; Radiated immunity 10 V/m (27 MHz‑500 MHz); 2 kV EFT withstand for 60 seconds

Key Functional Advantages

The T8451 adopts a six‑element voting output array for all channels. Each channel performs independent processing via triple slices before hardware‑voted output. Single switching‑element faults will not interrupt control. It implements SIL 3‑compliant safety logic with first‑level fault tolerance and second‑level fail‑safe de‑energization, mitigating unintended actuation risks of field actuator loops.

Built‑in independent SOE event logging with 1 ms resolution accurately captures trigger timestamps of field‑loop currents. It supports accident traceability and fault sequence analysis to meet process‑safety audit requirements.

Optional per‑channel line monitoring can be enabled on demand. It real‑time detects circuit open‑circuits, load short‑circuits and loose wiring. Fault alarms are transmitted to the Trusted processor and visually indicated via front‑panel LEDs.

2500 V DC optocoupler isolation isolates the backplane bus from high‑interference field loops, effectively suppressing electromagnetic interference generated by variable‑frequency drives and high‑power motors.

Hot‑swap replacement without system shutdown is supported. Upon removal of a faulty module, the standby‑slot module temporarily takes over outputs. The controller copies configuration parameters to the new module online with zero system downtime and no safety interruption.

Mechanical key‑locking anti‑mismatch slots. Differentiated mechanical keys are fitted for the T8451 and other I/O modules of the same series to prevent system logic failure caused by mis‑insertion.

Integrated automatic overcurrent‑protection circuits for all channels eliminate the need for loop fuses, reducing spare‑part replacement frequency and field‑rework workload during operation & maintenance.

Product Features

40 complete TMR triple‑modular redundant output channels per module; high‑density integration reduces cabinet space occupation.

Five electrically‑isolated output groups, each with independent shared field power supply and return wiring.

Six‑unit hardware voting output array with full‑link fault diagnosis and periodic self‑testing.

Front‑panel per‑channel status LEDs and module fault indicator for visual on‑site inspection.

On‑board high‑precision 1 ms Sequence‑of‑Events (SOE) logging memory unit.

Programmable per‑channel line‑fault monitoring for commissioning with various load types.

Fuse‑less automatic short‑circuit and overcurrent protection design.

Hot‑swap online replacement supported with coordinated switching via standby SmartSlot.

Compatible with all I/O slots of Trusted controller main racks and expansion racks.

Certified to IEC 61508 SIL 3 for safety‑instrumented system deployment.

Redundant backplane dual‑power‑bus power supply improves module power‑supply stability.

Application Fields

The ICS TRIPLEX T8451 targets process‑industry safety control systems requiring SIL 3 safety integrity level. Key industry segments are listed below:

‑ Oil & Gas: Off‑shore platforms and refinery ESD emergency shutdown systems, FGS fire‑and‑gas detection systems; for driving shut‑off valves, vent valves and fire audible‑visual alarms.

‑ Thermal Power / New Energy: Furnace safety‑supervision systems (FSSS), turbine protection systems; control trip solenoid valves and unit cooling actuators.

‑ Fine Chemical / Coal Chemical: Safety interlocks for reactor over‑temperature and over‑pressure conditions; output control for toxic‑media shut‑off loops.

‑ Long‑distance Oil & Gas Pipelines: Drive systems for pipeline pressure‑interlock emergency shut‑down valves.

‑ Pharmaceutical Special‑process: Explosion‑proof safety interlock output loops for high‑risk reaction workshops.

‑ Metallurgical High‑temperature Furnaces: Actuator loops for safe shutdown upon furnace pressure and temperature over‑limit conditions.