The Pepperl+Fuchs KFD2-STC4-Ex2 SMART transmitter power supply provides intrinsic safety for analog signals. This 2-channel isolated barrier powers 2-wire transmitters located in hazardous areas. Each channel independently supplies at least 16V at 20mA to the field device. The control side outputs a standard 0/4-20 mA signal proportional to the input. Furthermore, the Pepperl+Fuchs KFD2-STC4-Ex2 supports bidirectional HART communication. Test points on the terminals simplify commissioning and troubleshooting. Its narrow 20mm housing saves space in your cabinet.
Number of channels: 2 (isolated from each other).
Rated voltage: 20 ... 35 V DC (24V DC nominal via Power Rail or terminals 14+, 15-).
Power dissipation: 1.8 W.
Power consumption: Max. 2.7 W.
Output signal: 0/4 ... 20 mA (overload > 25 mA).
Load capacity: 0 ... 550 Ω at 20 mA.
Ripple: Max. 50 µA rms.
Accuracy deviation at 20°C: ≤ 10 µA (includes calibration, linearity, hysteresis, load, and supply variations).
Temperature influence: 0.25 µA/K.
Settling time: 200 µs.
Rise/fall time: 20 µs.
Safety rating: Up to SIL2 per IEC/EN 61508.
Housing dimensions (W x H x D): 20 x 124 x 115 mm (type B2).
Weight: Approx. 150 g.
The Pepperl+Fuchs KFD2-STC4-Ex2 connects to 2-wire SMART transmitters.
Connection terminals per channel: Channel 1 uses terminals 1+ and 3-; channel 2 uses terminals 4+ and 6-.
Available voltage at field side: ≥ 16 V at 20 mA (terminals 1+ and 3-).
Input signal range: 0/4 ... 20 mA.
HART communication: Fully supported in both directions.
The output repeats the input current signal for your PLC, DCS, or indicator.
Connection terminals: Channel 1 uses terminals 7- and 8+; channel 2 uses terminals 10- and 11+.
Output signal range: 0/4 ... 20 mA (linear with input).
Maximum load: 550 Ω at 20 mA.
Overload behavior: Output limits at approximately 25 mA.
Test points: Built into terminals for easy current measurement without breaking the loop.
The KFD2-STC4-Ex2 passes HART frequencies without distortion.
Bandwidth from field to control side: 0 ... 7.5 kHz (-3 dB) with 1 Vpp signal.
Bandwidth from control to field side: 0.3 ... 7.5 kHz (-3 dB) with 1 Vss signal.
This means you can connect a HART communicator or asset management system to either side. The barrier maintains signal integrity for digital communication.
Accuracy is exceptional for a 2-channel device. The total deviation stays within 10 µA at room temperature. Temperature drift adds only 0.25 µA per degree Kelvin. Therefore the Pepperl+Fuchs KFD2-STC4-Ex2 suits precise process measurements like pressure, flow, or level.
Engineers designed this barrier for functional safety applications. It meets SIL2 requirements according to IEC/EN 61508. Use it in safety instrumented functions (SIF) up to SIL2. For instance, integrate it into an emergency shutdown system for pressure or temperature monitoring.
The KFD2-STC4-Ex2 carries multiple certifications for global use.
ATEX markings:
[Ex ia Ga] IIC for gas zones 0, 1, 2.
[Ex ia Da] IIIC for dust zones 20, 21, 22.
[Ex ia Ma] I for mining applications.
Also Ex nA IIC T4 Gc for Zone 2 mounting.
Intrinsically safe output parameters (each channel):
Voltage Uo: 25.2 V.
Current Io: 93 mA.
Power Po: 0.586 W.
Maximum safe voltage (Um): 250 V (do not exceed).
IECEx certificates: IECEx BAS 04.0015X and IECEx CML 15.0055X.
UL/cULus approval: Control drawing 116-0428.
The Pepperl+Fuchs KFD2-STC4-Ex2 provides safe electrical isolation between input/output and input/power supply.
Isolation rating: 375 V peak per IEC/EN 60079-11.
Output/power supply: Functional insulation at 50 V AC.
Output/output (channel to channel): Functional insulation at 50 V AC.
This isolation prevents ground loops and protects your control system from hazardous area energy.
First, mount the Pepperl+Fuchs KFD2-STC4-Ex2 on a 35 mm DIN rail per EN 60715. You have two power options: use the Power Rail for daisy-chained 24V DC, or connect directly to terminals 14+ and 15-. The narrow 20mm housing fits densely packed panels.
Next, connect your 2-wire SMART transmitter to the Ex-side terminals. For channel 1, use terminals 1+ (positive) and 3- (negative). For channel 2, use terminals 4+ and 6-. Use shielded twisted-pair cable for the field wiring.
Then connect the control-side outputs to your analog input card. Channel 1 uses terminals 8+ (positive) and 7- (negative). Channel 2 uses terminals 11+ and 10-. The test points allow you to insert a milliamp meter without disconnecting wires.
Finally, power up the system. The LED indicators confirm proper operation. Perform a loop check using a HART communicator to verify digital communication.
1 x Pepperl+Fuchs KFD2-STC4-Ex2 SMART transmitter power supply
1 x Terminal label sheet (pre-printed)
1 x Installation instruction leaflet
Carriers: FedEx, UPS, DHL.
All orders include tracking and basic insurance. Express shipping typically delivers within 3-5 business days.
1. Can the KFD2-STC4-Ex2 power two separate 4-20mA transmitters?
Yes. The Pepperl+Fuchs KFD2-STC4-Ex2 has two completely independent channels. Each channel powers its own 2-wire transmitter and provides a separate 4-20mA output. Channels are isolated from each other.
2. Does this barrier support HART communication on both channels simultaneously?
Yes. Both channels support bidirectional HART communication. You can connect a HART communicator to either the field side or the control side. The 0-7.5 kHz bandwidth passes HART frequencies without attenuation.
3. What happens if the load resistance exceeds 550 ohms?
The output will not drive the required 20mA into a load above 550Ω. The signal will clip or distort. Always ensure your analog input card presents a load of 550Ω or less. For higher loads, consider a different barrier with active output.
4. How do I use the test points on the KFD2-STC4-Ex2?
The test points are integrated into the screw terminals. You can insert a multimeter probe into the test point while the wire remains connected. This allows you to measure loop current without breaking the circuit or interrupting the signal.
5. Is this device approved for mounting in Zone 2?
Yes. The Pepperl+Fuchs KFD2-STC4-Ex2 carries Ex nA IIC T4 Gc approval (TÜV 99 ATEX 1499 X). This means you can install the device itself in Zone 2 hazardous areas. The field side remains Ex ia for connection to Zone 0.
| Brand Name | Pepperl+Fuchs |
| Model No. | KFD2-STC4-EX2 |
| Product Type | Transmitter Power Supply |
| hasMerchantReturnPolicy | Adjust according to reality |
| Shippingdetails | Adjust according to reality |
