Pepperl+Fuchs KFD2-SRA-Ex4 4-Channel Switch Amplifier

Technical Overview

4-channel isolated barrier with intrinsic safety for digital inputs from hazardous areas, featuring 2:1 wiring and relay outputs.

Key Features

4-channel isolated barrier.
24 V DC supply (Power Rail compatible).
Dry contact or NAMUR inputs.
50 % less wiring due to 2:1 technology.
Relay contact output (form A normally open).
Line fault detection (LFD).
Reversible mode of operation.
IP20 degree of protection.
Suitable for hazardous environments (intrinsically safe for equipment protection levels Ga, Gb, Gc, Da, Db, Dc, Ma, Mb, and mounting in Division 2).
DIN rail mounting.

Technical Specification Matrix

Parameter	Value
Number of Channels	4
Supply Voltage (Rated)	19 ... 30 V DC
Supply Current (Rated)	45 ... 70 mA
Power Dissipation	1.2 W
Input Type	Dry contact or NAMUR inputs
Input Open Circuit Voltage	approx. 8 V DC
Input Short-Circuit Current	approx. 8 mA
Switching Point / Hysteresis	1.2 ... 2.1 mA / approx. 0.2 mA
Output Type	Relay Contact (1 form A normally open per channel)
Output Voltage	253 V AC / 40 V DC
Output Current	2 A
Degree of Protection	IP20
Ambient Temperature	-20 ... 60 °C (-4 ... 140 °F)
Connection	Screw terminals or Power Rail
Mounting	35 mm DIN mounting rail
Intrinsic Safety Marking	II (1)G [Ex ia Ga] IIC, II (1)D [Ex ia Da] IIIC, I (M1) [Ex ia Ma] I
Physical Weight (kg)	0.15
Dimensions L x W x H (cm)	11.5 x 2 x 11.9

Industrial Applications

1. Chemical Processing Plant Safety Monitoring

Monitoring the status of safety interlock switches on processing tanks or pipelines in chemical plants where flammable gases or vapors are present.

Problem Solved

The KFD2-SRA-Ex4 provides intrinsically safe circuits (Ga, Gb, Gc, Da, Db, Dc, Ma, Mb) for NAMUR sensors or dry contacts in hazardous areas, preventing ignition. Its 4 channels monitor multiple switches, and line fault detection ensures wiring integrity, signaling to safe area control systems.

Intrinsic safetyhazardous areaNAMUR sensordry contactrelay outputline fault detectionchemical processingZone 1Division 2

2. Oil & Gas Pipeline Valve Position Monitoring

Detecting the open/closed position of critical valves along oil or gas pipelines that traverse potentially explosive atmospheres.

Problem Solved

The device's intrinsic safety (Ex ia IIC) enables safe installation and operation with sensors in explosion-risk zones. The 2:1 wiring technology (when paired with compatible sensors) reduces cabling costs for extensive pipelines, while 24V DC supply and DIN rail mounting allow easy integration into remote terminal units (RTUs) or local control panels.

Oil and gaspipelinevalve positionlimit switchNAMUR sensorintrinsic safety2:1 wiringhazardous areaDIN rail24 V DC

3. Pharmaceutical Powder Handling System Level Detection

Monitoring powder levels in hoppers or silos within pharmaceutical manufacturing facilities prone to combustible dusts.

Problem Solved

The KFD2-SRA-Ex4 ensures intrinsically safe circuits for level sensors in dusty hazardous areas (Ex ia Da / Ex ia IIIC), preventing combustible dust ignition. Its 4 channels monitor multiple points, with relay outputs triggering alarms or controlling feeder systems in the safe area. The IP20 rating is suitable for installation within a protective control cabinet.

Combustible dustpharmaceutical manufacturinglevel detectionintrinsic safetyhazardous locationNAMUR inputdry contactrelay outputIP20