Pepperl+Fuchs KFD2-SR2-EX1.W.LB Isolated Switch Amplifier

Technical Overview

1-channel isolated barrier for intrinsic safety, transferring digital signals from hazardous to safe areas with SIL 2 compliance, LFD, and relay outputs.

Key Features

1-channel isolated barrier
24 V DC supply (Power Rail compatible)
Dry contact or NAMUR inputs
Usable as signal splitter (1 input and 2 outputs)
Relay contact output
Fault relay contact output
Line fault detection (LFD)
Reversible mode of operation
Up to SIL 2 (SC 3) according to IEC/EN 61508
Collective error messaging available when used with Power Rail system
DIN rail mounting

Technical Specification Matrix

Parameter	Value
Signal Type	Digital Input
Safety Integrity Level (SIL)	SIL 2
Systematic Capability (SC)	SC 3
Supply Connection	Power Rail or terminals 14+, 15-
Rated Voltage (Ur)	20 ... 30 V DC
Ripple	≤ 10 %
Rated Current (Ir)	≤ 50 mA
Power Dissipation	1 W
Power Consumption	< 1.3 W
Input Connection Side	Field side
Input Type	Dry contact or NAMUR inputs
Open Circuit Voltage/Short-Circuit Current (Input)	approx. 8 V DC / approx. 8 mA
Switching Point/Hysteresis (Input)	1.2 ... 2.1 mA / approx. 0.2 mA
Line Fault Detection (Input)	breakage I ≤ 0.1 mA, short-circuit I > 6 mA
Output Connection Side	Control side
Output Type	Relay contact (Output I: signal; Output II: signal or error message)
Contact Loading (AC)	253 V AC/2 A/cos φ > 0.7
Contact Loading (AC - alternate)	126.5 V AC/4 A/cos φ > 0.7
Galvanic Isolation (Input/Output)	Reinforced insulation according to IEC/EN 61010-1, rated insulation voltage 300 Veff
Galvanic Isolation (Input/Supply)	Reinforced insulation according to IEC/EN 61010-1, rated insulation voltage 300 Veff
Degree of Protection	IP20
Mounting	on 35 mm DIN mounting rail acc. to EN 60715:2001
Ambient Temperature Range	-40 ... +70 °C (Note: Some distributors list -20 to +60 °C, but official datasheet indicates wider range)
Physical Weight (kg)	0.15
Dimensions L x W x H (cm)	11.5 x 2 x 11.9

Industrial Applications

1. Process Control in Chemical Plants with Hazardous Areas

Monitoring the status of limit switches or proximity sensors located in potentially explosive atmospheres (Zone 0, 1, or 2) within a chemical processing facility. The KFD2-SR2-EX1.W.LB acts as an intrinsic safety barrier, safely transferring the digital status signals (e.g., valve open/closed, tank level switch activation) from the hazardous area to the plant's safe-area control system (PLC/DCS).

Problem Solved

Ensures safe operation by preventing ignition in hazardous areas, as the barrier limits energy transferred to the field device. It also provides reliable signal integrity and fault detection (LFD) for critical process parameters. The SIL 2 rating ensures the safety function meets regulatory requirements.

Intrinsic safetyhazardous area (Ex ia)NAMUR sensordry contactdigital inputrelay outputprocess monitoringchemical processingSIL 2line fault detectionexplosion protection

2. Emergency Shutdown Systems (ESD) in Oil & Gas Facilities

Integrating emergency shutdown pushbuttons or safety interlock switches from an intrinsically safe field environment (e.g., offshore platform, refinery) into an ESD system. The KFD2-SR2-EX1.W.LB receives the digital input from these safety devices and provides galvanically isolated relay outputs to the ESD logic solver in the safe area.

Problem Solved

Guarantees that critical safety signals from hazardous environments are reliably and safely transmitted to the ESD system. The SIL 2 capability ensures the integrity of the safety loop, and the fault relay output can alert operators to wiring faults in the field circuit, enhancing overall system reliability and response time.

Emergency Shutdown (ESD)safety interlockhazardous locationintrinsically safe barrierSIL 2digital inputrelay outputfault detectionoil & gasprocess safety

3. Conveyor System Monitoring in Mining Operations

Monitoring the status of pull-cord switches, belt misalignment switches, or speed sensors on conveyor belts operating in potentially dusty or explosive atmospheres (e.g., coal mines). The KFD2-SR2-EX1.W.LB isolates the signals from the hazardous area field devices, providing clean, safe relay contacts to the conveyor control system, enabling safe start/stop procedures and fault diagnostics.

Problem Solved

Protects personnel and equipment by ensuring that digital inputs from safety switches in explosive dust environments are safely processed without introducing an ignition risk. The IP20 rating is acceptable for installation within an enclosure in the safe area, and its robust design ensures reliable operation in demanding industrial settings.

Conveyor systemmininghazardous dust atmospheredigital inputNAMUR sensordry contactisolated barrierrelay outputIP20safety interlockmachine safety