Pepperl Fuchs KFD2-STC4-Ex2 Signal Conditioner Isolator Module

epperl+Fuchs KFD2-STC4-Ex2 Signal Conditioner / Isolated Barrier Module

 

 

The Pepperl+Fuchs KFD2-STC4-Ex2 is an intrinsically safe signal conditioner / isolator (SMART transmitter power supply module) used to safely transmit 4–20 mA analog signals between field instruments in hazardous areas (Ex zone) and PLC/DCS control systems.

Basic Information

• Part Number: KFD2-STC4-Ex2
• Brand: Pepperl+Fuchs
• Type: Signal Conditioner / Isolated Barrier / Transmitter Power Supply
• Function: Signal isolation + power supply + analog signal transmission (4–20 mA)

Technical Specifications (Core)

• Channel Type: 2-channel isolated barrier (analog)
• Signal Range: 0/4–20 mA analog input & output
• Supply Voltage: 20–35 VDC (Power Rail or terminals)
• Output Load: typically up to 550 Ω @ 20 mA
• Function: signal isolation + intrinsic safety barrier + transmitter supply
• Mounting: 35 mm DIN rail
• SIL Rating: up to SIL 2 (safety application dependent)

Key Features

• Provides galvanic isolation between field and control side
• Supplies power to 2-wire 4–20 mA transmitters
• Converts and transfers analog signals safely to PLC/DCS
• Supports HART / SMART communication
• Intrinsically safe design for hazardous area (Ex applications)
• High accuracy and low signal deviation

System Role (Important)

This module is typically used between:

• Field devices (pressure / flow / temperature transmitters)
  ➡️
• Safe area control system (PLC / DCS AI card)

It ensures:

• No explosion risk from electrical energy
• Signal accuracy over long cable distances
• Electrical isolation and noise protection

Application Areas

• Oil & gas plants
• Chemical / petrochemical industries
• Offshore platforms
• Power plants
• Refinery automation systems
• Water treatment plants
• Any ATEX / IECEx hazardous area instrumentation system

Advantages

• Strong electrical isolation (protects PLC and field devices)
• Intrinsic safety for Ex zone applications
• High signal stability for 4–20 mA loops
• Easy DIN rail installation
• Supports modern SMART/HART transmitters
• Reduces wiring complexity in control cabinets

Precautions

• Must be installed according to Ex safety regulations
• Correct loop resistance must be maintained (important for 4–20 mA)
• Do not bypass intrinsic safety barriers
• Ensure proper grounding of Power Rail system
• Use only approved field wiring for hazardous area side