Product Overview
The Pepperl+Fuchs KFU8-SR-Ex2.W is a 2-channel isolated barrier switch amplifier from the K-System, designed for intrinsic safety applications in hazardous areas. It transfers digital signals from NAMUR sensors or dry contact mechanical switches from the hazardous area to the safe area with relay contact output.
This device features line fault detection (LFD) for monitoring field circuit breakage and short-circuit conditions, and supports SIL 2 (SC 3) functional safety rating according to IEC/EN 61508, making it ideal for safety-critical applications.
Universal Power Supply: Operates on either 19-30V DC or 90-253V AC (50-60Hz), providing global compatibility with any control system without the need for a separate DC power supply.
Key Specifications
| Model |
KFU8-SR-Ex2.W |
| Brand |
Pepperl+Fuchs |
| Product Type |
Switch Amplifier / 2-Channel Isolated Barrier |
| Signal Type |
Digital Input |
| Input Types |
NAMUR (acc. to EN 60947-5-6) or Dry Contact |
| Output |
Relay Contact Output (Form C changeover, 2 channels) |
| Supply Voltage |
19-30V DC / 90-253V AC 50-60Hz |
| Safety Rating |
SIL 2 (SC 3) acc. to IEC/EN 61508 |
| Line Fault Detection (LFD) |
Yes (breakage ≤0.1mA, short-circuit >6mA) |
| Switching Frequency |
≤ 10 Hz |
| Contact Loading |
250V AC/2A, 126.5V AC/4A, 40V DC/2A resistive load |
| Ambient Temperature |
-40°C to 60°C (extendable to 70°C with proper mounting) |
| Protection Rating |
IP20 |
| Dimensions (WxHxD) |
20 x 119 x 115 mm (B2 housing) |
| Mounting |
35mm DIN rail acc. to EN 60715 |
| Weight |
approx. 150 g |
| Certifications |
ATEX, IECEx, UL, SIL2, CCC Ex, DNV Marine |
| Part Status |
Active / Current Model |
Key Features
2-Channel Isolated Barrier
- Two independent input/output channels in a single 20mm wide housing — saves cabinet space
- Each channel provides galvanic isolation between field and control circuits
Universal Power Supply
- Wide-range input: 19-30V DC OR 90-253V AC (50-60Hz)
- Eliminates the need for separate DC power supplies
- Compatible with global power systems — works anywhere in the world
SIL 2 Functional Safety
- SIL 2 (SC 3) certified according to IEC/EN 61508
- TUV Rheinland Functional Safety Certificate: 968/FSP 2319.00/22
- Suitable for safety-related applications in process industries
Line Fault Detection (LFD)
- Monitors field circuit for wire breakage (I ≤ 0.1 mA) and short-circuit (I > 6 mA)
- Provides diagnostic indication for preventive maintenance
- Fault relay output for remote error indication
Flexible Input Options
- Accepts NAMUR sensors (acc. to EN 60947-5-6) or dry contact mechanical switches
- Open circuit voltage: approx. 8V DC / short-circuit current: approx. 8mA
- Switching point: 1.2 ... 2.1 mA, hysteresis approx. 0.2 mA
Relay Output
- Form C changeover relay contacts for versatile load switching
- Mechanical life: 10⁷ switching cycles
- Energized/De-energized delay: approx. 20 ms
Reinforced Galvanic Isolation
- Reinforced insulation between input/output, input/power supply, output/power supply, and output/output
- Rated insulation voltage: 300 Veff acc. to IEC/EN 61010-1
- Safe electrical isolation acc. to IEC/EN 60079-11 (375V peak)
Easy Configuration
- DIP switch configuration for easy setup — no software required
- Space for labeling at the front for clear identification
- LED indicators for operating status and fault conditions per NAMUR NE44
DIP Switch Configuration
| Switch |
Function |
| S1 |
Reverses normal output state (energized ↔ de-energized) |
| S2 |
Reverses output state for second channel |
| S3 |
Enables/disables Line Fault Detection (LFD) |
Refer to the instruction manual for detailed configuration guidance.
Function Description
This isolated barrier is used for intrinsic safety applications. It transfers digital signals (NAMUR sensors/mechanical contacts) from a hazardous area to a safe area.
The proximity sensor or switch controls a form C changeover relay contact for the safe area load. The normal output state can be reversed using switches S1 and S2. Switch S3 is used to enable or disable line fault detection of the field circuit.
During an error condition, the relays revert to their de-energized state and the LEDs indicate the fault according to NAMUR NE44.
Applications
| Industry |
Application Examples |
| Oil & Gas |
Level monitoring, flow control, valve position feedback in hazardous areas |
| Chemical / Pharmaceutical |
Tank level measurement, reactor monitoring, process control |
| Power Generation |
Turbine monitoring, boiler control, coal handling systems |
| Mining |
Conveyor monitoring, equipment control in explosive atmospheres |
| Water/Wastewater |
Pump control, level switching in potentially explosive environments |
| Food & Beverage |
Process monitoring in solvent-handling areas |
Typical Use Cases:
- Intrinsic safety barriers for hazardous area sensors
- NAMUR proximity sensor interfacing
- Mechanical switch signal transfer from Zone 0/1/2 areas
- Functional safety systems requiring SIL 2 rating
- Remote status monitoring and fault detection
Wiring Connections
| Terminal |
Function |
| 1+, 2+, 3- |
Channel 1: Field side input (NAMUR or dry contact) |
| 4+, 5+, 6- |
Channel 2: Field side input (NAMUR or dry contact) |
| 7, 8, 9 |
Output I: Signal relay (Form C changeover) |
| 10, 11, 12 |
Output II: Signal relay (Form C changeover) |
| 14, 15 |
Power supply: 19-30V DC or 90-253V AC |
Certifications & Compliance
ATEX: FIDI 22 ATEX 0029X — II 3(1)G Ex ec nC [ia Ga] IIC T4 Gc
IECEx: IECEx FIDI 22.0003X — Ex ec nC [ia Ga] IIC T4 Gc
SIL 2: 968/FSP 2319.00/22 — TUV Rheinland Functional Safety
UL/cULus: E106378 — Hazardous Locations
CCC Ex: 2023322316005169 — China
DNV Marine: TAA00001WX — Marine applications
RoHS: Compliant — Environmentally friendly
CE: DOC-6610 — EU Directives
Environmental & Mechanical Specifications
| Operating Temperature |
-40°C to 60°C (-40°F to 140°F) |
| Extended Temperature |
Up to 70°C (158°F) with proper mounting |
| Protection Rating |
IP20 |
| Mounting |
35mm DIN rail acc. to EN 60715 |
| Housing Type |
B2 (20mm width) |
| Connection |
Screw terminals |
| Vibration Resistance |
2g (according to IEC 60068-2-6) |
Ordering Information
| Manufacturer |
Pepperl+Fuchs SE |
| Part Number |
KFU8-SR-Ex2.W |
| Product Status |
Active / Current Model |
| List Price |
$340.00 USD (reference) |
| Country of Origin |
Germany / Singapore |
| Packaging |
Factory sealed box |
| GTIN |
4050143515226 |
Recommended Accessories
| Accessory |
Model |
Description |
| Terminal Block |
KF-ST-5GN |
3-pin screw terminal, green, 5 pieces |
| Terminal Block |
KF-ST-5BU |
3-pin screw terminal, blue, 5 pieces |
| Coding Pins |
KF-CP |
For terminal block coding, 20 x 6 pins |
Key Benefits
Enhanced Safety
SIL2 certification and Ex ia input protection for hazardous areas
Global Compatibility
Universal AC/DC power supply works anywhere in the world
Reduced Downtime
Line fault detection enables predictive maintenance
Space Saving
2 channels in a 20mm wide housing maximizes cabinet density
Easy Commissioning
DIP switch configuration eliminates software tools
Proven Reliability
Pepperl+Fuchs K-System trusted in industrial safety worldwide
Comprehensive Certifications
ATEX, IECEx, UL, SIL2, CCC Ex, DNV — one product for global use
Wide Temperature Range
-40°C to 70°C for harsh environments
Fast Response
10 Hz switching frequency with 20 ms delay times
Need support? Contact us for:
- Technical specifications and complete datasheets
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