2. Model Definition

1. 51304642: Base model for 16-channel galvanically isolated non-HART 4–20mA analog input FTA

2. -325: Ultra heavy-duty extreme harsh industrial PCB grade

   • Ultra-thick multi-layer full-board reinforced conformal coating; leading resistance to high humidity, heavy dust, salt mist and moderate–strong corrosive chemical vapors

   • Hybrid TVS+gas discharge tube (GDT) ultra-high-energy lightning-rated bidirectional surge suppression per isolated channel

   • Four-stage cascaded RC differential EMI filter network for extreme high-noise MCC/VFD/medium voltage switchgear environments

   • Independent full per-channel galvanic isolation barriers to completely eliminate field-DCS ground loop circulating currents

   • Ultra-tight tolerance isolated loop current limiting resistors for perfectly uniform short-circuit overload protection across all 16 input channels

   • Extra-wide reinforced physical channel isolation partitions to eliminate cross-channel signal leakage, measurement drift and crosstalk

   • Nickel-plated compression screw terminals and PCB solder pads to resist oxidation, salt fog and chemical corrosion long-term

3. Matched IOP Hardware: Honeywell 16-channel galvanically isolated non-HART 4–20mA analog input UCN IOP card

4. Incompatible Hardware: Isolated HART AI (51304518), non-isolated AI/AO FTAs, isolated non-HART AO (51304640), discrete DI/DO, TC/RTD LLAI, pulse counter, serial communication termination blocks

3. Technical Specifications

1. Channel Count: 16 fully galvanically isolated non-HART 4–20mA analog input channels

2. Supported Field Devices

   • Two-wire conventional non-HART 4–20mA transmitters: pressure, differential pressure, mass/vortex/turbine flow, radar/float level, RTD/TC temperature, pH, ORP, dissolved oxygen, conductivity analytical transmitters

3. FTA Structure: Passive isolated termination block with no onboard power supply; integrated per-channel four-stage filtering, hybrid lightning surge protection, short-circuit overload current limiting

4. PCB Protection: Ultra-thick multi-layer reinforced conformal coating; flammability UL94 V0

5. Terminal Type: Nickel-plated compression screw terminals, compatible with solid/stranded copper wire up to 14 AWG; each channel has independent isolated terminal pair

6. Form Factor: Standard Size B footprint, snap-on DIN rail mount for 35 mm standard rails

7. Operating Ambient: 0℃ ~ +60℃ indoor cabinet only; maximum humidity, dust, salt fog and corrosion tolerance within the entire 51304642 product lineup

8. Circuit Architecture

   • Four-stage low-pass EMI filtering to suppress extreme switching noise from large VFD banks, motor control centers and medium-voltage distribution switchgear

   • Hybrid TVS+GDT ultra-high-energy bidirectional transient overvoltage surge suppression on each isolated field input pair (lightning transient withstand certified)

   • Galvanic isolation barrier eliminates ground potential offset errors between multi-grounded field equipment and DCS cabinet ground grid

   • Calibrated ultra-low-tolerance isolated current-limit resistors prevent transmitter burnout and IOP high-impedance input damage during field short faults

   • Extra-thick isolation partitions to fully block inter-channel analog bleed and cross-input measurement drift interference

9. Redundancy Compatibility: Fully supports primary/standby redundant isolated non-HART AI IOP architecture; hot-swap IOP card replacement permitted

10. Approximate Unit Weight: 0.362 kg

4. Interface & Communication Configuration

1. Inner IOP Connection: Locking heavy-duty flat ribbon cable connector directly mates to isolated non-HART AI IOP pin headers. Heavy reinforced cable strain relief prevents pin header deformation or fracture under sustained tension of long multi-core field instrument wiring harnesses. Isolated pure DC 4–20mA analog current signals pass through galvanic barriers, four-stage filters and hybrid lightning-grade surge networks directly to the IOP. The IOP executes high-precision A/D conversion, open/short loop fault diagnostics, and transmits process value data to Experion PKS controller over the UCN bus; no onboard signal amplification or conversion logic.

2. Field Outer Terminals: Every channel features independent nickel-plated isolated Ch+ / Loop– terminals for two-wire transmitter wiring; field loop excitation circuit is fully galvanically separated from DCS control ground potential.

3. Loop Excitation Power Source: Regulated isolated 4–20mA loop excitation current sourced exclusively from paired isolated non-HART AI IOP card through FTA passive protection networks.

5. Core Functions

1. Cable Strain Relief: Heavy-duty reinforced strain relief safeguards fragile isolated AI IOP pin headers from mechanical stress, bending and fatigue fracture caused by continuous pulling force of long multi-core field instrument cables.

2. Four-Stage Extreme EMI Noise Rejection: Four-layer cascaded filter architecture drastically outperforms -100/-125/-175/-200 grades, completely eliminating PV drift, measurement jitter and unstable readings in extreme high-noise motor/VFD and power switchgear zones.

3. Ultra-Heavy Lightning-Grade Surge & Short-Circuit Protection: Hybrid TVS+GDT surge stack absorbs intense lightning-induced transients, large wiring short spikes and heavy switching arcs; precision current-limit resistors cut fault current instantly, delivering maximum protection for sensitive isolated high-impedance IOP analog input circuits.

4. Ultra Heavy-Duty Anti-Corrosion & Anti-Oxidation Environmental Barrier: Ultra-thick multi-layer conformal coating fully encapsulates PCB substrate, traces and passive components; nickel-plated terminals and solder pads resist oxidation, salt fog and strong chemical fumes, delivering multi-year stable operation in coastal, offshore, fertilizer and heavy chemical cabinet atmospheres.

5. Full Galvanic Ground Loop Elimination: Independent per-channel galvanic isolation completely stops circulating ground loop currents from disparate field equipment and DCS cabinet ground potentials, resolving unstable measurements and hardware degradation common in large multi-plant grounding layouts.

6. Uniform Isolated Loop Protection Consistency: Precision ultra-tight tolerance isolated current-limit resistors deliver identical overload cutoff threshold across all 16 channels for perfectly matched transmitter fault protection.

7. Independent Single-Channel Maintenance: Nickel-plated isolated terminal blocks support transmitter replacement, full loop resistance/hi-pot insulation testing and fault troubleshooting for one measurement loop without disrupting the other 15 critical process input circuits.

8. Redundancy Hot-Swap Capability: Standby redundant isolated non-HART AI IOP cards can be replaced online without losing critical pressure, flow, level, temperature and analytical PV values, batch process profile data or equipment fault alarms.

6. Application Scenarios

Applicable Industries

Isolated Non-HART Analog Measurement Loops

Cabinet Deployment

7. Wiring, Operation & Maintenance Guidelines

Wiring Standards

1. Two-wire transmitter wiring: Transmitter positive → nickel-plated isolated FTA Ch+, transmitter negative → isolated Loop–; reversed polarity creates significant measurement offset and accelerates terminal corrosion aging.

2. Deploy high-grade shielded twisted-pair low-capacitance instrument cable for all field runs; implement single-point shield grounding only at DCS cabinet FTA side to eliminate ground loop noise and measurement drift.

3. Route isolated AI analog cables physically separated from high-current AC power, MCC and VFD output wiring; maintain maximum practical separation from large motor power feeders to minimize EMI coupling interference.

Spare Part Interchangeability

Standard Fault Troubleshooting Flow