- Automation & ControlView all 1,920 products
- AC Drives
- PLC & I/O Cards
- Industrial Communications
- Vibration Monitoring
- Automation Accessories
- Controllers & Data Acquisition
- Isolator & Barrier
- CCTV & Security
- Safety Switches & Guard Locking
- Encoders
- HMI Displays
- Industrial Computers
- Motor Soft Starters
- Servo Drives
- Pneumatic Cylinders
- Machine Vision
- Automation Software
- Robotics
Brand: Pepperl+Fuchs
Pepperl+Fuchs KFD2-SR2-Ex1.W Relay Switch Amplifier
Description
KFD2-SR2-Ex1.W single-channel relay switch amplifier
The KFD2-SR2-Ex1.W is the classic one-channel relay barrier of the Pepperl+Fuchs K-System. It takes a NAMUR proximity sensor or a mechanical contact from a hazardous area, isolates it, and switches a changeover relay in the safe area. It is one of the most widely used building blocks for position and status signals in process plants.
Decoding the part number: KFD2 for the 24 V DC isolated barrier, SR2 the relay switch amplifier generation 2, Ex1 one channel and .W the suffix used in the datasheet title for this relay version, which is rated down to -40 °C. The two-channel version is the KFD2-SR2-Ex2.W.
Seven Star LLC supplies this module in Oman and the GCC as an independent supplier in Muscat.
Technical specifications of the KFD2-SR2-Ex1.W
| Parameter | Specification |
|---|---|
| Manufacturer / part number | Pepperl+Fuchs KFD2-SR2-Ex1.W |
| Input | NAMUR sensor or dry contact, EN 60947-5-6; terminals 1+, 2+, 3- |
| Open circuit voltage / short-circuit current | approx. 8 V DC / approx. 8 mA |
| Switching point / hysteresis | 1.2 to 2.1 mA / approx. 0.2 mA |
| Line fault detection | Breakage I ≤ 0.1 mA, short-circuit I > 6 mA |
| Output | 1 relay changeover, terminals 7, 8, 9; 250 V AC / 2 A, 126.5 V AC / 4 A, 40 V DC / 2 A resistive; min. 2 mA at 24 V DC |
| Delay / life | approx. 20 ms energize and de-energize; 107 cycles; frequency < 10 Hz |
| Supply | 19 to 30 V DC, Power Rail or terminals 14+/15-; ≤ 35 mA, ≤ 0.7 W |
| Functional safety | SIL 2, SC 3 acc. to IEC/EN 61508 |
| Hazardous area data | PTB 00 ATEX 2080, [Ex ia Ga] IIC; Uo 10.5 V, Io 13 mA, Po 34 mW; TUV 99 ATEX 1493 X, II 3G Ex ec nC IIC T4 Gc |
| Isolation | Reinforced, 300 Veff input/output, input/supply, output/supply |
| Ambient temperature | -40 to 70 °C |
| Housing | Type B2, 20 x 119 x 115 mm, IP20, approx. 150 g |
How the KFD2-SR2-Ex1.W behaves in normal and fault conditions
A NAMUR sensor changes its loop current across the 1.2 to 2.1 mA window; the KFD2-SR2-Ex1.W follows with a relay change after about 20 ms. DIP switches reverse the relay logic and can disable line fault detection for plain contacts. In a fault condition (cut cable below 0.1 mA, short above 6 mA) the relay drops to its de-energized state and an LED indicates the condition per NAMUR NE 44.
When mounted on a Power Rail, a collective error message is fed to the rail so a single alarm summarizes all modules. The relay output is potential-free, so it can switch mains-voltage coils or 24 V DC lamps within the contact ratings.
System fit and related parts
The relay of the KFD2-SR2-Ex1.W suits legacy or hard-wired panels, solenoid circuits and interposing relays. Where the PLC card is electronic and a 200 µs response is needed, the KFD2-SOT3-Ex1.LB is faster. In tight racks, the KCD2-SR-Ex1.LB gives two relays in 12.5 mm. The related KFD2-SR2-Ex2.W provides two channels in the same housing width.
Selection and ordering checklist
- Sensor is NAMUR or a contact with the resistor network.
- Check relay load, including inductive loads (cos phi above 0.75).
- Check -40 to 70 °C against the cabinet.
- Normal or reversed relay action.
- Ex ia data of the sensor against the module output values.
- Supply or Power Rail.
Installation, commissioning and maintenance of the KFD2-SR2-Ex1.W
Mount on DIN rail, wire the sensor to terminals 1+, 2+ and 3-, set the DIP switches and check each state of the sensor and the cable. For high-cycle signals consider the 10 million operation relay life and plan replacement; for inductive loads use suppression across the coil.
Keep a spare module available for critical loops and document switch positions to make like-for-like replacement quick.
Common wiring and troubleshooting points
Most field complaints on a KFD2-SR2-Ex1.W loop come from the sensor wiring rather than the module. A relay that never switches usually means the loop current stays outside the 1.2 to 2.1 mA window, for example because a 3-wire sensor was connected instead of a NAMUR type or the resistor pair on a contact is missing. A relay that chatters points to water in a junction box or a marginal contact.
Check the LED against the cable: with line fault detection on, a lit fault LED and a de-energized relay mean breakage or short. Measure the loop current with the cable disconnected from terminals 1+ and 3- while respecting the hazardous-area rules for live work, and compare with the 8 mA short-circuit figure from the datasheet. Always replace a failed module with the same part number, because DIP defaults and relay wiring differ between versions.
Typical applications in Oman and the GCC
The KFD2-SR2-Ex1.W is applied to valve limit switches, tank level switches and motor status contacts across upstream oil and gas, refineries, power plants and desalination sites in the GCC, often in hot cabinets where the -40 to 70 °C rating gives headroom.
Family comparison
| Part | Key difference |
|---|---|
| KFD2-SR2-Ex1.W (this part) | 1 channel, 1 relay, 20 mm, -40 to 70 °C |
| KFD2-SR2-Ex2.W | 2 channels, 1 relay each |
| KCD2-SR-Ex1.LB | 1 channel, 2 relays, 12.5 mm |
| KFD2-SH-Ex1 | Safety version, SIL 3 |
Information to send with an RFQ
- Part number KFD2-SR2-Ex1.W and quantity
- Sensor type and Ex data
- Relay load type and voltage
- Supply method
- Delivery location
Documents and quotation
The manufacturer datasheet for KFD2-SR2-Ex1.W is attached on this page, so you can check wiring, approvals and dimensions before ordering. Send the exact part number, quantity and delivery location in Oman or the GCC and Seven Star LLC will reply with a quotation.
Seven Star LLC is an independent supplier in Muscat and is not the manufacturer; confirm availability, lead time and any project approval requirements in your RFQ.
Datasheets & Documents
- Datasheet Pepperl+Fuchs KFD2-SR2-Ex1.W Datasheet Download
Reviews (0)
About brand
Pepperl+Fuchs is a German manufacturer of industrial sensors and explosion protection equipment, founded in 1945 in Mannheim by Walter Pepperl and Ludwig Fuchs as a radio repair shop. Defective transformers led them into manufacturing, and the company developed its first proximity switch in the late 1950s. Pepperl+Fuchs is headquartered in Mannheim and is a pioneer of intrinsically safe electrical equipment for hazardous areas.
Seven Star LLC lists Pepperl+Fuchs sensors, isolated barriers, power supplies and hazardous-area mobile devices, and supplies them to instrument and automation teams in Oman by exact model designation.
Pepperl+Fuchs company profile
| Founded | 1945, Mannheim-Sandhofen, Germany, by Walter Pepperl and Ludwig Fuchs |
|---|---|
| Headquarters | Mannheim, Germany |
| Ownership | Privately owned (Pepperl+Fuchs SE) |
| Origins | Radio repair workshop that began making replacement transformers |
| Product families | Inductive, capacitive, ultrasonic and photoelectric sensors, rotary encoders, R2000 LiDAR scanners, KFD and HiC isolated barriers, Zener barriers, remote I/O, purge and pressurization systems, Ex-rated enclosures |
Milestones
- 1945: Walter Pepperl and Ludwig Fuchs open their radio repair shop in Mannheim.
- 1958: The first proximity switch is developed (some company sources say 1959).
Pepperl+Fuchs product families on this page
On the interface side there are two systems. The K-System mounts on DIN rail and is represented here by the KFD2-UT2-Ex2 universal temperature converter. The H-System plugs into termination boards and is represented by the HiD2030 SMART transmitter power supply with HART. The PS1000-A6-24.20 is a 24 VDC, 20 A power supply for cabinets. Sensors listed include the NJ2-12GK-SN NAMUR inductive sensor, the R101 retro-reflective photoelectric sensor and the R2000 2-D LiDAR scanner. For field staff there are the Tab-Ex 05 DZ1 tablet for Zone 1/21 areas and the Smart-Ex 03 DZ2 smartphone for Zone 2/22 and Division 2 areas.
Where Pepperl+Fuchs equipment is used
Isolated barriers sit between field instruments in Zone 0 or Zone 1 and the DCS or safety system in refineries, gas plants and chemical works. NAMUR sensors report valve position and machine states in classified areas. Photoelectric sensors and LiDAR scanners work in conveying, packaging, warehousing and vehicle guidance. Ex-rated tablets and phones are carried on operator rounds and maintenance jobs.
Pepperl+Fuchs products we list
Ordering Pepperl+Fuchs parts: what we need
Send the complete model designation as printed on the device, including every suffix; a single letter can change the supply voltage or the output type. Add the part number if the label shows one. For barriers, tell us the field device and signal type, the number of channels and whether the safety loop needs a SIL-assessed module. For mobile devices, state the zone or division and the regional radio version.
Facts checked against Pepperl+Fuchs's own chronicle pages, October 2026.
Browse Pepperl+Fuchs products by category: Sensors & Transmitters, Industrial Computer, Isolator & Barrier, Power Modules.
FAQ
Questions about the Pepperl+Fuchs KFD2-SR2-Ex1.W Relay Switch Amplifier
Answers from our engineering team on installation, compatibility and integration.
01What is the KFD2-SR2-Ex1.W used for?
It isolates a NAMUR sensor or dry contact in a hazardous area and switches a relay in the safe area, with line fault detection.
02What relay ratings apply?
250 V AC at 2 A, 126.5 V AC at 4 A or 40 V DC at 2 A resistive, with at least 2 mA at 24 V DC for reliable switching.
03Can the action be reversed?
Yes, DIP switches reverse the mode of operation and can switch off line fault detection.
04How much power does it need?
Up to 35 mA at 19 to 30 V DC, with power dissipation and consumption of up to 0.7 W.
05What temperature range is given?
-40 to 70 °C, in a type B2 housing 20 mm wide.
Reviews
There are no reviews yet.