2. Model Definition

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

-325: Ultra heavy-duty reinforced PCB protection grade

Thick multi-layer military-grade full-board conformal coating, exceptional resistance to extreme humidity, conductive heavy dust, moderate-severe corrosive chemical vapors and intermittent light salt mist

Multi-stage composite high-energy bidirectional surge stack (TVS + fast transient absorber), far higher transient withstand energy than -200 and lower grades, with per-channel isolated protection

Three-stage fully symmetrical cascaded RC differential EMI filter, precision calibrated for ultra-high-noise heavy industrial zones with massive VFD clusters, full MCC banks and medium-voltage switchgear, zero attenuation/distortion to HART FSK carrier

Independent reinforced galvanic isolation barrier for each channel; no electrical connection between field loop, DCS ground and adjacent channels

Oversized high-current reinforced flyback freewheeling diode arrays to fully dissipate extreme back-EMF spikes from extra-large inductive heavy-load actuator coils

Ultra-precision ultra-tight tolerance series damping resistors for perfectly uniform full-range 4–20mA linear stroke response across all 16 channels

Extra-wide ultra-thick flame-retardant reinforced plastic channel baffles to fully eliminate inter-channel analog leakage and HART signal crosstalk

3. Technical Specifications

Channel Count: 16 fully independent loops, complete galvanic isolation per output channel

Compatible Field Devices

Two-wire critical heavy-duty HART smart valve positioners, ultra-high-load electro-pneumatic HART I/P transducers, oversized 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 with no internal power supply; integrated per-channel low-distortion HART coupling, three-stage symmetrical differential filtering, multi-tier ultra-high-energy surge protection and extreme heavy inductive kickback suppression

PCB Protection: Thick multi-layer military reinforced conformal coating; flammability UL94 V0

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

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

Operating Ambient: 0℃ ~ +60℃ indoor control cabinet; humidity, dust and moderate-severe corrosion tolerance greatly exceeds -200 and lower grades; tolerates intermittent light salt mist; continuous heavy coastal salt fog requires upgrade to -375 grade

Circuit Architecture Parameters

Three-stage symmetrical low-pass differential filtering suppresses extreme industrial EMI without distorting HART waveform or 4–20mA drive amplitude

Multi-tier composite bidirectional surge stack clamps extreme positive/negative transient high voltage on every isolated output loop

Per-channel galvanic isolation completely eliminates stroke drift and HART handshake instability caused by field-DCS ground potential differences, works reliably for multi-ground complex plants

Ultra-tight precision damping resistors fully eliminate valve hunting and stabilize full-span 4–20mA linear output performance

Oversized high-current flyback diodes rapidly absorb extreme back-EMF energy from large heavy inductive actuator coils

Ultra-thick flame-retardant baffles fully block inter-channel analog bleed and cross-channel HART interference

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

Approximate Unit Weight: 0.363 kg

4. Interface & Communication Configuration

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

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

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: Permanently eliminates ground loop interference, stable operation for both multi-ground complex plants and single-ground layouts.

Three-stage symmetrical ultra-heavy EMI rejection: Suppresses extreme intense electromagnetic interference from large VFD systems, MCC banks and medium-voltage switchgear to eliminate severe valve hunting, large setpoint fluctuation and frequent HART communication retries.

Multi-tier ultra-high-energy surge & short-circuit protection: Withstands lightning-induced line transients, high-magnitude startup surges and field short-circuit high voltage to protect expensive sensitive IOP output power semiconductors and critical heavy-duty field actuators.

Extreme heavy-duty uniform inductive load protection: Oversized flyback diode arrays evenly protect all channels from coil back-EMF damage for uninterrupted long-term critical process operation.

Consistent channel linearity & stable HART synchronization: Ultra-precision matched passive components deliver identical valve stroke response and reliable HART handshake across all 16 channels to reduce bulk calibration workload.

Redundant hot-swappable operation: Seamlessly synchronizes with primary/standby IOP switching logic; single-channel disconnection and troubleshooting do not impact operation of remaining 15 critical control loops.

6. Application Scenarios

Applicable Industries

Large integrated petrochemical complexes, heavy chemical synthesis plants, combined heat & power generation stations, massive oil & gas refineries, pulp & paper mills, high-humidity industrial wastewater treatment, heavy-batch pharmaceutical manufacturing lines, inland coastal sites with intermittent light salt mist

Typical Control Loops

Critical emergency safety shutoff heavy-duty HART smart valve positioners

High-pressure large-flow process throttle HART modulating actuators

Oversized furnace draft air damper high-load HART I/P transducers

High-volume blending loop heavy smart HART positioners

High-pressure reduction large modulating HART actuators

Ideal for multi-ground complex plant layouts, ultra-dense VFD heavy-noise process areas, cabinets with persistent extreme high humidity and heavy conductive dust, atmospheres with moderate-to-severe acidic/alkaline volatile vapors, inland sites with occasional light salt mist. Not suitable for offshore platforms or coastal locations with continuous heavy salt fog exposure (upgrade to -375 for full salt fog resistance).

7. Wiring Standards

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

Cable specification: Heavy-duty 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.