1. Introduction

• Function: Speed monitor input field termination & conditioning (SIFTA)

• Channels: 9 speed input channels (3 groups × 3 channels)

• Sensor Types: Passive magnetic/inductive; active open‑collector; active totem‑pole

• Signal: Pulse/frequency input (speed), isolated per group

• Safety: SIL 3 (with T8442), CE, UL, CSA, ATEX, IECEx

• Isolation: Group‑to‑group & field‑to‑system galvanic isolation

• Mounting: Standard DIN rail

• Operating Temp: –40 °C to +70 °C (harsh environment rated)

2. Product Overview

• 3 sensor groups (×3 channels): Independent power and isolation per group for fault containment.

• Multi‑sensor compatibility: Works with passive magnetic pickups (no external power), active open‑collector, and active totem‑pole sensors (field‑powered).

• Field‑replaceable fuses: Per‑group and per‑channel fuses, replaceable in situ.

• Galvanic isolation: 2500 VDC between groups; field side isolated from T8442 system side.

• LED diagnostics: Per‑channel and per‑group status LEDs for power, signal, and fault indication.

• SIL 3 certified system: When paired with T8442, meets IEC 61508 SIL 3 for overspeed/underspeed protection.

• Turbine overspeed/underspeed protection (steam/gas turbines)

• Compressor and pump speed monitoring

• Generator shaft speed & phase reference

• Critical rotating machinery ESD interlocks

• Burner management system (BMS) fuel pump speed validation

3. Specifications

3.1 Mechanical

• Form Factor: DIN‑rail mount enclosure (compact, industrial grade)

• Dimensions (H × W × D): 102 mm × 391 mm × 127 mm

• Weight: Approx. 0.75 kg

• Mounting: Standard 35 mm DIN rail (horizontal)

• Termination: Screw terminals (field sensors); ribbon cable to T8442

• Protection: IP20 (enclosed), conformal coated PCB (T8846C available)

3.2 Electrical

• System Interface: Ribbon cable to T8442 TMR speed monitor module

• Field Sensor Groups: 3 independent groups (G1, G2, G3), 3 channels each (CH1–CH9)

• Sensor Types & Input Ranges:

  • Passive magnetic/inductive: 20 mV–30 Vpp, 1 Hz–20 kHz

  • Active open‑collector: 5–24 VDC, sinking, 1 Hz–20 kHz

  • Active totem‑pole: 5–24 VDC, sourcing/sinking, 1 Hz–20 kHz

• Field Supply (Active Sensors): 24 VDC ±10 %, per group isolated, 50 mA max per group

• Isolation: 2500 VDC (group‑to‑group); 2500 VDC (field ↔ T8442 system)

• Fusing: Per‑channel (100 mA); per‑group (500 mA), field‑replaceable

• Surge Protection: TVS diodes per channel (±30 V)

• Signal Conditioning: Schmitt trigger, low‑pass filter (20 kHz), level shifting

• Power Consumption: ≤ 15 W (all groups active)

3.3 Functional

• Redundancy: TMR system (via T8442); FTA provides 3‑way signal splitting

• Channel Mapping: 9 inputs → T8442 9‑channel TMR speed monitor

• Diagnostics:

  • Per‑channel signal presence (LED)

  • Per‑group power healthy (LED)

  • Fuse fault indication (per group)

  • Short circuit protection (per channel)

  • Open sensor detection (active sensors)

• Response Time: ≤ 1 ms (sensor pulse to T8442 input)

• Fault Tolerance: Single‑channel/group fault does not affect other groups or TMR voting

3.4 Environmental

• Operating Temperature: –40 °C to +70 °C

• Storage Temperature: –40 °C to +85 °C

• Humidity: 5–95 % RH, non‑condensing

• Vibration: 10–57 Hz ±0.15 mm; 57–150 Hz 2.0 g

• Shock: 30 g, ½ sine wave, 11 ms

• Hazardous Area: ATEX / IECEx Ex ia IIC T4 Ga (with external barriers)

3.5 Safety & Certification

• Safety Standard: IEC 61508 SIL 3 (system with T8442, TÜV Certified)

• Approvals: CE, UL, CSA, ATEX, IECEx, FM

• Fault Tolerance: TMR 3‑2‑0 (system level); FTA provides isolated group redundancy

• PFHd: < 5.0 × 10⁻⁹ / hour (system with T8442)

4. Front Panel Indicators

• PWR G1/G2/G3 (Green): ON = group power healthy

• CH1–CH9 (Yellow): Flashing = pulse signal present; OFF = no signal/fault

• FUSE G1/G2/G3 (Red): ON = group fuse blown

5. Installation

• Mounting: Attach to standard 35 mm DIN rail in control cabinet (horizontal)

• Orientation: Keep vents clear; allow 50 mm clearance top/bottom for airflow

• Cabling: Route field sensor cables away from high‑power AC cables (EMI avoidance)

• System Connection: Connect ribbon cable from T8846 to T8442 module in T8100/T8400 chassis

• Environmental Note: Use T8846C (conformal coated) for > 85 % RH, salt mist, or corrosive vapor environments

6. Wiring

• Passive Magnetic/Inductive Sensors: Connect to CHx terminals (no external power)

• Active Open‑Collector Sensors: Connect to CHx + 24 VDC (group supply)

• Active Totem‑Pole Sensors: Connect to CHx + 24 VDC (group supply)

• Field Power: 24 VDC ±10 % to G1/G2/G3 power terminals (isolated per group)

• Shielding: Sensor cable shields grounded at T8846 only (single‑point grounding)

• Wire Gauge: 18–24 AWG, twisted pair, shielded for speed signals

7. Ordering Information

• T8846: Standard Speed Monitor Input FTA (SIFTA), –40 °C to +70 °C

• T8846C: Conformal coated Speed Monitor Input FTA (harsh environments)

• T8442: TMR Speed Monitor Module (Trusted T8000 chassis)

• T8100 / T8400: Trusted system chassis

• T8840: Standard 40‑channel analog output FTA (for reference)