2. Model Definition

51304728: Base model for 16-channel galvanically isolated HART analog output FTA

-175: Medium heavy-duty reinforced PCB protection grade

Medium-thick reinforced full-board conformal coating with enhanced resistance to high humidity, heavy dust and mild-moderate corrosive gas

High-capacity bidirectional TVS surge suppression for transients, ESD and line faults, higher impact energy tolerance than -100/-125, with per-channel isolated protection

Three-stage cascaded RC differential EMI filter optimized for high-noise plant areas with dense MCC and large VFD clusters

Independent galvanic isolation barrier for each channel, no shared ground between field loop and DCS control side

Oversized reinforced flyback freewheeling diode arrays for complete dissipation of large inductive actuator coil back-EMF spikes

Precision tight-tolerance series damping resistors for perfectly uniform 4–20mA linear stroke response across all channels

Extra-thick reinforced plastic channel baffles to eliminate inter-channel analog/HART signal leakage and crosstalk

3. Technical Specifications

Channel Count: 16 fully independent channels, complete galvanic isolation per output loop

Compatible Field Devices

Two-wire HART smart valve positioners, heavy-duty electro-pneumatic HART I/P transducers, linear/rotary HART modulating actuators

Backward compatible with conventional non-HART 4–20mA pneumatic positioners and standard I/P converters

FTA Structure: Passive isolated termination board without built-in power supply; integrated per-channel HART coupling, three-stage differential filtering, high-energy surge protection and heavy inductive kickback suppression

PCB Protection: Medium-thick reinforced conformal coating; flammability UL94 V0

Terminal Type: Compression screw terminals compatible with solid/stranded copper wire up to 14 AWG; each channel has isolated Ch+ / Loop– field terminals fully separated from DCS ground and other loops

Form Factor: Standard B-size footprint, snap-on DIN rail mounting for standard 35 mm rails

Operating Ambient: 0℃ ~ +60℃ indoor cabinet; superior humidity, dust and mild corrosion tolerance versus -100/-125; not designed for continuous salt fog environments

Circuit Architecture Parameters

Three-stage low-pass differential filtering suppresses severe EMI interference from large VFD systems, motor control centers and medium-voltage switchgear while fully preserving HART carrier amplitude

High-energy bidirectional TVS suppresses positive/negative transient high voltage on each isolated output loop

Per-channel galvanic isolation completely eliminates valve stroke drift and unstable HART communication induced by field-to-DCS ground potential offset

Calibrated tight-tolerance damping resistors eliminate valve hunting and stabilize full-range 4–20mA linearity

Oversized flyback diodes rapidly absorb severe back-EMF generated by heavy inductive actuator loads

Extra-thick baffles fully block inter-channel analog bleed and HART signal crosstalk

Redundancy Support: Fully compatible with primary/standby redundant isolated HART AO IOP; hot-swap FTA replacement without process shutdown is permitted

Approximate Unit Weight: 0.360 kg

4. Interface & Communication Configuration

Inner IOP Connection: Locking heavy-duty flat ribbon cable directly mates to isolated HART AO IOP pin headers. Reinforced cable strain relief prevents pin header deformation or fracture under sustained tension of long multi-core field control wiring harnesses.

Field Outer Terminals: Independent isolated Ch+ / Loop– terminals for each two-wire actuator loop; every loop is electrically isolated from DCS ground and adjacent channels.

Signal Mechanism: 4–20mA DC analog drive signals overlaid with FSK HART digital signals via frequency division; low-distortion passive HART coupling integrated per isolated channel circuit.

HART Access: No dedicated auxiliary communication port; handheld HART communicator clamps directly across isolated Ch+ and Loop– field terminals for commissioning, calibration and diagnostic data reading.

5. Core Functions

Full per-channel galvanic isolation: Eradicates ground loop interference, stable operation applicable to both multi-ground and single-ground plant layouts.

Three-stage heavy EMI noise rejection: Suppresses intense electromagnetic interference from VFD banks, MCCs and medium-voltage switchgear to eliminate valve hunting, setpoint drift and frequent HART poll retries.

High-energy surge & inductive kickback fault protection: Withstands lightning-induced line transients, equipment startup surges and field short-circuit high voltage to protect costly sensitive IOP output power semiconductors and field actuators.

Uniform linear output performance: Precision matched passive components deliver consistent valve stroke response and stable HART handshake across all 16 channels to reduce bulk calibration workload.

Strong inter-channel signal isolation: Extra-thick partition baffles greatly restrain analog and HART crosstalk between adjacent control loops.

Redundant hot-swappable maintenance: Seamlessly follows primary/standby IOP switching logic; single-channel disconnection and troubleshooting do not affect operation of the remaining 15 control loops.

6. Application Scenarios

Applicable Industries

Petrochemical complexes, medium-heavy chemical plants, combined heat & power stations, large oil & gas refineries, pulp & paper mills, high-humidity wastewater treatment, medium-to-high humidity pharmaceutical batch production lines

Typical Control Loops

Emergency safety shutoff HART smart valve positioners

High-pressure throttle modulating HART actuators

Large furnace draft air damper HART I/P transducers

Process blending control valve smart HART positioners

Pressure reduction modulating HART actuators

Suitable for multi-ground and single-ground plant layouts, VFD-dense process areas, cabinets with long-term high humidity and heavy dust accumulation, and atmospheres containing mild-moderate acidic/alkaline volatile vapors. Not applicable for offshore platforms or coastal sites with continuous salt fog exposure.

7. Wiring Standards

Two-wire actuator wiring: Actuator positive → isolated FTA Ch+, actuator negative → FTA Loop–; reversed polarity weakens kickback suppression efficiency and degrades HART waveform integrity.

Cable specification: Shielded twisted-pair instrument cable for all field wiring runs; cable shield grounded solely at DCS cabinet FTA side with field equipment end ungrounded to fully suppress residual noise.

Power cable segregation: Physically separate HART analog control cables from high-voltage AC power, MCC and VFD output wiring to minimize capacitive and inductive EMI coupling interference.

8. Incompatible Hardware

All non-isolated AI/AO FTAs (51304718, 51304685, 51304672, 51304690), isolated HART AI (51304644), isolated non-HART AI (51304650), isolated non-HART AO (51304640), discrete DI/DO termination boards, TC/RTD dedicated FTAs, pulse counter termination blocks and serial communication terminal assemblies cannot be paired with this isolated HART AO IOP card.