KFD2-STC4-Ex2 SMART Transmitter Power Supply

Product Overview

• 2-channel isolated barrier for SMART transmitters.
• Provides 24 V DC supply via Power Rail or terminals.
• Input accepts 2-wire SMART transmitters, 0/4…20 mA.
• Output repeats 0/4…20 mA signal to control system.
• Up to SIL 2 rated per IEC/EN 61508.
• Compact housing B2, 20 x 124 x 115 mm.
• LED indication and front labeling space.

Key Features

• Galvanic isolation input/output/power.
• Test points on terminals for easy troubleshooting.
• High frequency response 0…7.5 kHz (-3 dB).
• Low deviation ≤ 10 µA at 20 °C.
• Ambient temperature range -20…60 °C.
• Protection class IP20, suitable for industrial environments.

Technical Specifications

• Brand: Pepperl+Fuchs
• Model: KFD2-STC4-Ex2
• Supply voltage: 20…35 V DC (Power Rail or terminals 14+,15-)
• Power consumption: max. 2.7 W
• Input (field side): terminals 1+,3- / 4+,6-; 0/4…20 mA
• Available voltage: ≥ 16 V at 20 mA
• Output (control side): terminals 7-,8+ / 10-,11+; 0/4…20 mA
• Load range: 0…550 Ω at 20 mA
• Ripple: max. 50 µA rms
• Deviation (20 °C): ≤ 10 µA (incl. calibration, linearity, hysteresis)
• Temperature influence: 0.25 µA/K
• Frequency range: field → control: 0…7.5 kHz; safe → hazard: 0.3…7.5 kHz
• Settling time: 200 µs
• Rise/fall time: 20 µs
• Hazardous area approval: [Ex ia Ga] IIC, [Ex ia Da] IIIC, [Ex ia Ma] I
• Maximum values (Uo/Io/Po): 25.2 V / 93 mA / 0.586 W
• Safe electrical isolation: 375 V peak (input/output, input/power)
• Ambient temperature: -20…60 °C (-4…140 °F)
• Protection degree: IP20
• Mounting: 35 mm DIN rail acc. EN 60715
• Weight: approx. 150 g

Installation & Commissioning

• Mounting: Snap on 35 mm DIN rail. Use terminals for wiring.
• Wiring: Field side terminals 1+,3- / 4+,6-; control side 7-,8+ / 10-,11+.
• Power: Connect 24 V DC via Power Rail or terminals 14+,15-.
• Test points: Built-in terminals allow easy current measurement.
• LED: Green LED indicates power status.
• Labeling: Front space for custom tag.

Compatibility

• Works with 2-wire SMART transmitters (HART compatible).
• Output 0/4…20 mA to PLC, DCS, or indicator.
• Functional insulation (50 V AC) between output and power supply.
• Safe isolation for hazardous zones: Ex ia, Ex nA.

Certifications

• ATEX: BAS 99 ATEX 7025 X (II 1(1)G, II 1(1)D, I (M1))
• ATEX (nA): TÜV 99 ATEX 1499 X (II 3G Ex nA II T4)
• IECEx: BAS 04.0015X / CML 15.0055X
• UL: E106378, Control Drawing 116-0428
• EMC: EN 61326-1:2013, NE 21:2011
• SIL 2 capable per IEC/EN 61508

Package Contents

• 1 x KFD2-STC4-Ex2 Isolated Barrier
• 1 x terminal label
• 1 x instruction manual (downloadable)

Warranty & Shipping

• Warranty: 12 months against manufacturing defects.
• Shipping: 12-24 hours dispatch (stock available).
• Carriers: FedEx, UPS, DHL (trackable).

Expert Review

“The KFD2-STC4-Ex2 delivers reliable signal isolation for SMART transmitters in hazardous areas. Its low power consumption and high accuracy (≤10 µA deviation) make it a top choice for safety loops. The test points speed up commissioning significantly.”

Manager’s Insight

“For plant managers, this barrier reduces downtime with fast troubleshooting and robust Ex certification. The 2-channel design saves rack space. We recommend it for SIL 2 applications where precision and safety are critical.”

Applications

• Oil & gas refineries (zone 0/1/2)
• Chemical plants with explosive atmospheres
• Pharmaceutical manufacturing
• Power generation and water treatment
• SMART transmitter signal conditioning

Compatible Devices

• 2-wire pressure, temperature, flow, level transmitters
• HART-enabled field devices
• PLC/DCS analog input cards (0/4…20 mA)

Frequently Asked Questions

• Can I use this with a 4-20 mA passive transmitter?Yes, it supplies 16 V at 20 mA to power 2-wire transmitters.
• What is the maximum load for the output?550 Ω at 20 mA. Higher loads may cause saturation.
• Is it suitable for HART communication?Yes, the frequency range (0.3…7.5 kHz) supports HART signals.
• How do I test the output without disconnecting?Use the built-in test points on terminals for safe measurement.
• What is the difference between functional and safe isolation?Safe isolation (375 V peak) protects against faults in hazardous zones.
• Which certification do I need for Zone 0?[Ex ia Ga] IIC is suitable for Zone 0 (gas) and Zone 20 (dust).

Selection Guide

• For 1-channel applications, consider KFD0-STC4-Ex1.
• For higher power, check KFD2-STC4-Ex2 (this model).
• Always verify Uo, Io, Po with your transmitter’s entity parameters.
• Choose this model if you need SIL 2 and dual-channel redundancy.

Contact Information

• Email: sales@powergearx.com
• WhatsApp: +86 18030005825

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