KFD2-VR4-EX1.26 – Vibration Input Isolator for Hazardous Areas

KFD2-VR4-EX1.26 Voltage Repeater – Precision Signal Isolation for Hazardous Areas

This 1‑channel isolated barrier converts vibration sensor inputs into a stable 0 V … −20 V output. It powers field devices, handles negative voltage signals, and meets SIL 2 safety standards. Designed for DIN‑rail mounting, it ensures reliable signal transmission in demanding industrial environments.

Key Features – MECE Classified

• Function & Signal Type
  • Analog input barrier for voltage signals
  • Input range: 0 V … −20 V (transmission range)
  • Output: 0 V … −20 V (load ≥9 kΩ for 3‑wire, ≥2 kΩ for 2‑wire)
  • Cut‑off frequency: 10 kHz (−0.1 dB) / 20 kHz (−1 dB)
  • DC transfer error <10 mV (with 10 kΩ load)
• Power Supply & Consumption
  • Rated voltage: 19 … 30 V DC (via Power Rail or terminals 11+/12‑)
  • Power dissipation ≤1.2 W, consumption ≤1.6 W
  • Functional insulation output/power supply (50 V AC)
• Performance & Accuracy
  • Input resistance: 10 kΩ (terminals 4‑common, 6‑/2‑)
  • Output resistance: 24 Ω typ. (27 Ω max)
  • Temperature drift <100 ppm/K
  • Ripple: <20 mVrms (200 kHz), <3 mVrms (20 kHz)
  • Time delay: 7.1 ±0.3 µs
• Environmental & Mechanical
  • Ambient temperature: −20 … +60 °C
  • Protection: IP20 (housing), mounting on 35 mm DIN‑rail
  • Dimensions: 20 x 119 x 115 mm, mass approx. 125 g
  • EMC: EN 61326‑1:2013 (industrial locations)
• Safety & Hazardous Area Approvals
  • SIL 2 acc. to IEC/EN 61508
  • ATEX: Ⅱ (1)G [Ex ia Ga] IIC, Ⅱ (1)D [Ex ia Da] IIIC, Ⅰ (M1) [Ex ia] I
  • IECEx: [Ex ia Ga] IIC, [Ex ia Da] IIIC, [Ex ia Ma] I; Ex nA II T4 Gc
  • UL/cULus: Control drawing 116‑0316
  • Galvanic isolation: 375 V peak (input/output, input/power)

Technical Data – at a Glance

• Brand: Pepperl+Fuchs
• Model: KFD2‑VR4‑EX1.26
• Series: K‑System (isolated barriers)
• Input: 0 … −20 V (vibration sensors)
• Output: 0 … −20 V (load ≥2 kΩ)
• Frequency response: 10 kHz (−0.1 dB)
• Sensitivity: full span 20 Vpp (sine wave)
• Linearity: DC error <10 mV
• Resolution: not specified (analog continuous)
• Temperature range: −20 … +60 °C
• Environmental tolerance: IP20, EMC compliant
• Noise immunity: ripple <20 mVrms (200 kHz)

Installation & Mounting

• Snap onto 35 mm DIN‑rail per EN 60715
• Use terminals 4 (common), 1,3,5 (supply‑), 2,6 (signal‑) for field side
• Control side: terminals 7‑ and 8+ for output
• Power via Power Rail or terminals 11+/12‑
• Observe safe maximum voltage Um = 253 V (input/output)

Commissioning & Maintenance Ease

• LED indicator for operating status
• Front labelling space for easy identification
• Screw terminals for secure wiring
• No routine calibration needed – drift <100 ppm/K
• Compact housing (B2) saves cabinet space

Compatibility & Accessories

• Works with 2‑wire and 3‑wire vibration sensors
• Power feed module: KFD2‑EB2(.R4A.B)(.SP)
• Universal power rail: UPR‑03(‑M)(‑S)
• Profile rail: K‑DUCT‑BU(‑UPR‑03)
• Compatible with most PLC analog input cards (0 … −20 V)

Certifications & Compliance

• ATEX: BAS 02 ATEX 7206, DMT 01 ATEX E 133, TÜV 99 ATEX 1499 X
• IECEx: BAS 05.0078, BAS 10.0085X
• UL: cULus (Control drawing 116‑0316)
• SIL 2 acc. to IEC/EN 61508
• EN 60079‑0:2012+A11:2013, EN 60079‑11:2012, EN 60079‑15:2010

Package Contents

• 1 x KFD2‑VR4‑EX1.26 Voltage Repeater
• 1 x terminal label set
• Instruction manual (digital download)
• Mounting accessories (DIN‑rail clips included)

Warranty & Shipping

• 12‑month warranty against manufacturing defects
• Same‑day dispatch (order before 2 PM UTC+8)
• Shipping: FedEx, UPS, DHL – tracking provided
• Estimated delivery: 12‑24 hours (domestic), 2‑5 days (international)

Expert Review – Manager’s Insight

“The KFD2‑VR4‑EX1.26 stands out for its ultra‑low output resistance (24 Ω) and fast 7 µs response – critical for vibration monitoring in turbines and compressors. Its SIL 2 rating and ATEX/IECEx approvals make it a safe choice for Zone 0/1 applications. We recommend pairing it with the UPR‑03 power rail for clean, distributed power. A reliable workhorse for critical signal chains.”

Typical Applications & Compatible Devices

• Vibration monitoring on motors, pumps, and fans
• Speed sensors (proximity probes) in hazardous areas
• Connecting IEPE/charge amplifiers to PLC/DCS
• Signal conditioning for accelerometers (100 mV/g)
• Use with Pepperl+Fuchs K‑System power supplies and termination boards

Frequently Asked Questions (FAQ)

• What is the input voltage range?
  • 0 V to −20 V (negative signal).
• Can I use it with a 2‑wire sensor?
  • Yes, minimum load is 2 kΩ for 2‑wire sensors.
• Is it suitable for SIL 2 loops?
  • Yes, it meets SIL 2 per IEC/EN 61508.
• What is the maximum output current?
  • It supplies >10 mA at −21 V (terminals 4‑5).
• Does it require external power?
  • Yes, 19‑30 V DC via Power Rail or terminals.
• How do I mount it?
  • Snap onto 35 mm DIN‑rail (EN 60715).
• Experience: What about AC superimposed signals?
  • AC components up to 20 Vpp (sine) are acceptable without errors.
• Selection guide: Which model for 4‑20 mA?
  • This is voltage‑only; use KFD2‑CD‑Ex series for current.

Selection Guide – Quick Advice

• Choose this unit if your sensor outputs negative voltage (0 … −20 V).
• For positive voltage signals, select KFD2‑VR‑Ex1.2x series.
• Need isolated power for the sensor? This barrier provides field supply.
• For higher channel count, use KFD2‑VR4‑EX1.26 with UPR‑03 rail.
• Always verify load impedance (≥9 kΩ for 3‑wire, ≥2 kΩ for 2‑wire).

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