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  • 1-channel isolated barrier
  • 24 V DC supply (Power Rail)
  • Input 2-wire and 3-wire SMART transmitters and 2-wire SMART current sources
  • Output 0/4 mA ... 20 mA
  • Terminals with test points
  • Up to SIL2 acc. to IEC 61508


This isolated barrier is used for intrinsic safety applications. The device supplies 2-wire and 3-wire SMART transmitters in a hazardous area, and can also be used with 2-wire SMART current sources.

t transfers the analog input signal to the safe area as an isolated current value.

Digital signals may be superimposed on the input signal in the hazardous or safe area and are transferred bi-directionally.

If the HART communication resistance in the loop is too low, the internal resistance of 250 Ω between terminals 8 and 9 can be used.

Test sockets for the connection of HART communicators are integrated into the terminals of the device.


The device supports the following SMART protocols:
  • HART
  • Foxboro
Technical Data
General specifications
Signal type Analog input
Connection Power Rail or terminals 14+, 15-
Rated voltage 20 ... 35 V DC
Ripple within the supply tolerance
Power loss 1.5 W
Power consumption 1.9 W
Connection terminals 1+, 2-, 3 or 5-, 6+
Input signal 0/4 ... 20 mA
Voltage drop Ud ≤ 2.4 V at 20 mA (terminals 5, 6)
Input resistance ≤ 64 Ω terminals 2-, 3 ; ≤ 500 Ω terminals 1+, 3 (250 Ω load)
Available voltage ≥ 16 V at 20 mA terminals 1+, 3
Connection terminals 7-, 8+, 9
Load 0 ... 800 Ω
Output signal 0/4 ... 20 mA (overload > 25 mA)
Ripple ≤ 50 μA rms
Transfer characteristics
  • at 20 °C (68 °F), 0/4 ... 20 mA
  • ≤ 10 μA incl. calibration, linearity, hysteresis, loads and fluctuations of supply voltage
Influence of ambient temperature 0.25 μA/K
Frequency range
  • field side into the control side: bandwidth with 0.5 Vpp signal 0 ... 7.5 kHz (-3 dB)
  • control side into the field side: bandwidth with 0.5 Vpp signal 0.3 ... 7.5 kHz (-3 dB)
Rise time 20 μs
Start-up time 200 μs
Electrical isolation
Output/power supply functional insulation, rated insulation voltage 50 V AC
Directive conformity
Electromagnetic compatibility
Directive 2004/108/EC EN 61326-1:2006
Electromagnetic compatibility NE 21:2006
Protection degree IEC 60529
Ambient conditions
Ambient temperature -20 ... 60 °C (-4 ... 140 °F)
Mechanical specifications
Protection degree IP20
Mass approx. 200 g
Dimensions 20 x 124 x 115 mm (0.8 x 4.9 x 4.5 in) , housing type B2
Data for application in connection with Ex-areas
EC-Type Examination Certificate BAS 99 ATEX 7060 , for additional certificates see www.pepperl-fuchs.com
Group, category, type of protection EX II (1)GD [Ex ia] IIC [circuit(s) in zone 0/1/2]
Input Ex ia IIC
Maximum safe voltage Um 250 V (Attention! The rated voltage can be lower.)
Equipment terminals 1+, 3-
Voltage Uo 25.4 V
Current Io 86.8 mA
Power Po 551 mW
Permissible connection values [EEx ia]
Equipment terminals 1+, 2 / 3-
Voltage Ui 30 V
Current Ii 115 mA
Voltage Uo 25.4 V
Current Io 115 mA
Power Po 584 mW
Permissible connection values [EEx ia]
Equipment terminals 5-, 6+
Voltage Ui 30 V
Current Ii 115 mA
Voltage Uo 8.7 V
Current Io 0 mA
Maximum safe voltage Um 250 V (Attention! The rated voltage can be lower.)
EC-Type Examination Certificate DMT 01 ATEX E 133
Group, category, type of protection EX I (M1) [Ex ia] I
Statement of conformity TÜV 99 ATEX 1499 X , observe statement of conformity
Group, category, type of protection, temperature class EX II 3G Ex nA II T4 [device in zone 2]
Electrical isolation
Input/Output safe electrical isolation acc. to IEC/EN 60079-11, voltage peak value 375 V
Input/power supply safe electrical isolation acc. to IEC/EN 60079-11, voltage peak value 375 V
Directive conformity
Directive 94/9/EC EN 60079-0:2006, EN 60079-11:2007, EN 61241-11:2006 , EN 60079-15:2005 , EN 50303:2000
International approvals
UL approval
Control drawing 116-0173 (cULus)
General information
Supplementary information EC-Type Examination Certificate, Statement of Conformity, Declaration of Conformity, Attestation of Conformity and instructions have to be observed where applicable. For information see www.pepperlfuchs.com.

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KFD2-STC4-EX1 : KFD2STC4EX1 Specification

Alternative Part Number: 231364

Manufacturer: Pepperl + Fuchs

Pricing Unit: Each

Weight: 0.150 kg (each)

Tariff code: 85365019

Discount code: PFPA10

PDF Product Datasheet for KFD2-STC4-EX1

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