Power supply and active barrier

Loop power supply with optional HART® diagnostics


from €116.-
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    • Loop power supply, wide range power supply, flexible power source

    • Bi-directional HART® transmission with SMART transmitters

    • Optional HART® diagnostics

    Specs at a glance

    Approval ATEX II (1) GD [EEx ia] IIC
    HART® signal Bidirectional
    Diagnostics Via HART® status bit or NE43
    Relay output Optional for HART® diagnostics
    Product / VersionPrice / pcs. in EUROrder code
    Power Supply; DiagnosticsApproval1 to 34 to 1011+
    StandardNon-hazardous area132,-122,-116,- RN221N-A1
    ATEX II (1)GD (Ex ia) IIC141,-132,-124,- RN221N-B1
    With Hart® diagnostic relayNon-hazardous area210,-195,-184,- RN221N-A3
    ATEX II (1)GD (Ex ia) IIC219,-204,-193,- RN221N-B3


    Product / VersionPrice / pcs. in EUROrder code
    Housing Field, R4 182x180x165, 5xM20, PC Protection housing Minitec. Synthetic housing with transparent cover. Protection IP66. 4x22.5mm / 2x45mm. Usage: FTL825.74,96 52010132

    Prices valid until 31.12.2020 in EUR per unit (not including shipping and applicable sales tax). See
    Endress+Hauser Terms and Conditions

  • Application

    The RN221N power supply is used for the galvanic isolation of 4 to 20 mA signal current circuits. It can also be applied for the intrinsically safe operation of 2-wire transmitters and to remove earth loops. The unit offers a sensor monitoring function as an option which monitors the HART® signal or the current loop for faults. The status of the measuring point is reported over an alarm relay.


    The RN221N active barrier supplies sensors with auxiliary energy and transmits the measuring signal to the output. The optional, intrinsically safe input circuit, conforms to the requirements for ignition classification ATEX II (1) GD.

    Application Example

    Application example of a power supply and barrier RN221N

    a) System component without own transmitter power supply (e.g. PLC, recorder, display)

    b) Commubox

    c) RN221N active barrier. (Transmitter set up using HART® communication)

    d) The intrinsically safe Cerabar S pressure transmitter is connected via the RN221N power supply with intrinsically safe input

  • Technical data

    Number of inputs 1
    Power requirement 16.7 V ± 0.2 V (at I = 20 mA)
    Open circuit voltage 26 V ± 5 %
    Short circuit current ≤40 mA
    Internal resistance 328 Ω
    Over range 10 %
    Reference conditions Calibration temperature at 25 °C (77 °F)
    Ambient temperature influence

    ≤0.1 % in range 0 to 50 °C (32 to 122 °F)

    ≤0.2 %/10 K in range –20 to 0 °C (–4 to 32 °F)

    Intrinsically safe input option
    Open circuit voltage 27.3 V
    Short circuit current 87.6 mA
    Power consumption 597 mW

    86 nF [EEx ia] IIC

    683 nF [EEx ia] IIB, [EEx ia] IIA


    5.2 mH [EEx ia] IIC

    18.9 mH [EEx ia] IIB, [EEx ia] IIA

    Number 1
    Open circuit voltage 24 V ± 10 %
    Over range 10 %
    Load (impedance) 0 to 700 Ω (without communication resistance)
    Galvanic isolation To all other current circuits
    Relay output Optional 250 V AC/30 V DC, 3A normally open/normally closed
    Power supply
    Power supply 20 to 250 V DC/AC, 50/60 Hz
    Power consumption

    Without HART® diagnosis max. 2.5 W

    with HART® diagnosis max. 5.0 W

    Current requirement (Input current limitation) Imax /In < 15
    Electrical safety To EN 61 010-1, protection Class I, over voltage category II, over current protection at installation (fuse) ≤ 10 A
    Performance characteristics
    Linearity ≤0.15 %
    Load influence ≤0.1 %
    Operating conditions
    Ambient temperature –20 to +50 °C (–4 to 122 °F)
    Storage temperature –20 to +70 °C (–4 to 158 °F)
    Climatic class To EN 60 654-1 Class B2
    Ingress protection IP 20
    EMC Immunity to EN 61326, Class A
    Mechanical construction
    Dimensions (W×H×D) 22.5 × 96 × 112 (0.89" × 3.78" × 4.33") for top hat DIN rail to EN 50 022-35
    Housing PC/ABS, UL 940

    Keyed plug-on screw terminals, core size 2.5 mm² solid, or strands with ferrules;

    front mounted communication socket for 2 mm (0.79") jack plugs

    Display and operating level
    Display elements LED yellow in series to current output: Illuminates, when output current circuit is closed
    LED current >2 mA
    Remote communication HART® communication: Communication signals are transmitted bi-directionally. Communication resistance: Resistance for HART® communication 250 Ω built in. Please take note of voltage drop!
    Ex approval ATEX II (1) GD [EEx ia] IIC

    Dimensions (in mm)

    Dimensions of an active barrier with power supply

    a) without HART® diagnosis

    b) with HART® diagnosis


    Installation according to instruction manual

    Electrical connection

    RN221N without HART® diagnostics

    Electrical connection of an active barrier RN221N

    a) HART® connection sockets

    b) Input (sensor) with loop power supply (intrinsically safe option)

    c) Active output 4 to 20 mA

    RN221N with HART® diagnostics

    Electrical connection of an active barrier RN221N with HART diagnostics option

    a) HART® connection sockets

    b) Input (sensor) with loop power supply (intrinsically safe option)

    c) Active output 4 to 20 mA

  • More documents for RN221N