PEPPERL+FUCHS KFD2-STC4-1 – Smart Transmitter Power Supply and Isolated 4–20 mA/HART Conditioner

The PEPPERL+FUCHS KFD2-STC4-1 is part of the well-known K-System, designed to power a 2-wire 4–20 mA transmitter and provide clean, galvanically isolated output to your DCS/PLC—while keeping HART signals transparent. From my experience, it’s a go-to in control cabinets where you want reliable loop isolation, easy commissioning, and a slim 12.5 mm footprint that saves rail space. You might notice that this specific “-1” variant is a single channel unit; it’s typically chosen for point applications where accuracy and stability matter more than channel density.

Company’s Order Placement Process and Guarantees

• Warranty: 365 days
• Delivery: 1 week if in stock; no more than one month at the latest
• Payment: 50% advance payment, full payment before delivery
• Express options: FedEx, UPS, DHL

Key Features

• 2-wire transmitter power supply – Provides loop power for a 4–20 mA field transmitter, simplifying wiring and marshalling.
• Galvanic isolation (3-port) – Isolates input, output, and supply to break ground loops and reduce noise pickup.
• HART transparency – Maintains HART communication through the loop for configuration and diagnostics.
• Single channel (“-1”) – A compact 12.5 mm module that typically fits dense cabinets without ventilation issues.
• Active or passive output (typical) – Suits different DCS/PLC analog input cards with flexible signal direction.
• Line fault monitoring (typical) – Detects open-circuit or short-circuit conditions on the field side, helping maintenance react faster.
• Power Rail compatible – Quick power distribution and collective error signaling when used with the K-System Power Rail.

Technical Specifications

Application Fields

The KFD2-STC4-1 fits almost any process segment where 4–20 mA/HART loops are standard:

• Chemicals & petrochemicals – isolating pressure, level, and flow transmitters before the marshalling cabinet.
• Oil & gas (safe-area loops) – when Ex approval isn’t required but robust isolation still is.
• Water & wastewater – stable analog loops to SCADA with easy HART access for diagnostics.
• Power generation – turbine auxiliary systems, cooling water skid instrumentation.
• Pharmaceuticals & food – clean cabinets, compact modules, and consistent loop behavior.

A maintenance lead at a municipal WTP told us they swapped older isolators for KFD2 units and saw fewer nuisance trips and faster HART handheld connections—minor things that, in many cases, save hours over a quarter.

Advantages & Value for Procurement

• Reliability – Pepperl+Fuchs K-System has a strong field track record; modules run cool and stable in most cabinets.
• Compatibility – HART pass-through, selectable output behavior, and a loop-friendly design that plays well with major DCS/PLC AI cards.
• Cabinet density – 12.5 mm width typically means fewer rails and enclosures—direct space and cost savings.
• Serviceability – Front-access terminals and clear status LEDs make loop checks straightforward.
• Lifecycle support – Broad availability and long-term product family continuity reduce replacement risk.

Installation & Maintenance

• Environment – Mount on a 35 mm DIN rail inside a ventilated cabinet; keep within -20…+60 °C ambient and avoid high vibration zones.
• Wiring – Use twisted, shielded pair for analog loops; terminate shields at one end to prevent ground loops. Verify output card mode (active vs passive) to match the module configuration.
• Power Rail – If using the K-System Power Rail, ensure correct polarity and end-feed module installation; this simplifies both power and collective error signaling.
• Safety – This “non-Ex” variant is typically used in safe-area loops. For hazardous areas, choose the Ex-rated version (e.g., KFD2-STC4-Ex1).
• Routine care – Periodically check terminal tightness, clean light dust with dry air, and verify loop ranges during planned outages. Firmware isn’t usually needed on this device class, so maintenance stays light.

Supporting Components (Optional)

• PEPPERL+FUCHS KFD2-EB2 Power Feed Module – Feeds 24 V DC to the K-System Power Rail and provides collective error signaling; recommended where multiple KFD2 modules share a backplane.
• K-System Power Rail – Backplane-style rail that distributes power and error bus; speeds installation and reduces wiring clutter compared to discrete feed-throughs.
• HART handheld/modem – Any standard HART communicator can be connected on the control side thanks to HART transparency.

Quality & Certifications

• Conformity – CE marking (EMC/Low Voltage), RoHS compliance.
• Approvals (typical for K-System) – UL/cUL recognized. Ex certifications apply to the Ex variants; this model is generally used in safe areas.
• Manufacturer quality – Produced under ISO 9001 quality systems.
• Warranty – 365 days from shipment.

If you’re standardizing on the K-System, the KFD2-STC4-1 seems to be a solid single-channel choice for clean, HART-friendly isolation. Send over your I/O card type and loop details, and we’ll confirm output mode and rail accessories so it lands right the first time.