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Product short description:
  • 4-20mA DC input
  • 4-20mA DC output
  • 12 to 50V DC @ 20mA (loop-powered)
  • 1500V AC peak isolation DC prevents ground loops

The 270i accepts a process current input and provides an isolated 4 to 20mA process current output signal. Power is received from the input signal current.

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The 270i accepts a process current input and provides an isolated 4 to 20mA process current output signal. Power is received from the input signal current.

These isolators use transformer isolation to effectively break the electrical path between the transmitted signal and the receiving device. This eliminates ground loops, reduces noise, and helps protect against transients for more accurate and reliable measurements.

This product is also extremely easy to install. All units are factory calibrated for loads up to 600 ohms to eliminate any need for load trim adjustments.

Approvals
CSA
Class I; Division 2; Groups A, B, C, D

270i Loop Powered Isolator Performance

Input

Input Range: 4 to 20mA input. Power is derived from the input signal loop. Input current should be limited to less than 50mA to prevent damage to the isolator. In the event of an open output circuit, the input loop voltage drop is limited to 20V, nominal. Isolator has reverse polarity protection.

Zero and span: Zero and span trim adjustments utilize 22-turn potentiometers accessible from front of the unit.

Input voltage drop: The voltage drop is a function of the input current and load resistance and is calculated as follows:
Input Voltage Drop = 5.4V DC + (0.0216A x RLOAD
Example (RLOAD = 250 ohms):
Input Voltage Drop = 5.4V DC + (0.0216A x 250 ohms) = 10.8V DC.

Current sense resistor: A built-in 10 ohm (±0.1%) resistor can monitor input current to the isolator. Wiring to the isolator’s input terminals determines if this resistor is included in the current loop. Use of this resistor provides a test signal of 40 to 200mV, representing 4 to 20mA.

Output

Output Range: 4-20mA DC output.
A. For RLOAD from 50 to 600 ohms, connect RLOAD between Output (+) and Output (-) terminals.
B. For RLOAD from 0 to 50 ohms, connect RLOAD between Output (S) and Output (-) terminals. For
optimum performance at low values of RLOAD, the isolator has a built-in pad resistor of 50 ohms.

1. Input Voltage Drop (input sense resistor not used): VDROP = 5.4V DC + (0.0216A x (RLOAD + 50 ohms))
2. Input Voltage Drop (input sense resistor used) VDROP = 5.6V DC + (0.0216A x (RLOAD + 50 ohms))

Accuracy: ±0.1% of output span. Error includes the combined effects of isolator repeatability, hysteresis, terminal point linearity and adjustment resolution.

Load resistance effect: Less than ±-0.1% of output span as load resistance is changed over entire range. Allows use of isolator, within resistance load range, without the need to recalibrate the isolator for a particular load.

Output ripple: Less than ±0.1% of the maximum output span.

Bandwidth: -3dB at 3Hz, typical.

Response time: For a step input, the output reaches 98% of output span in 180mS, typical.

Environmental

Ambient temperature range
Operating: -13 to 185°F (-25 to 85°C).
Storage: -40 to 185°F (-40 to 85°C).

Ambient temperature effect: Less than ±0.006% of output span per °F (±0.01% per °C) over the ambient temperature range for reference test conditions. This specification includes the combined effects of zero and span over temperature.

Isolation: The input and output circuits are isolated from each other for common-mode voltages up to 250V AC, or 354V DC off ground, on a continuous basis (will withstand 1500V AC dielectric strength test for one minute without breakdown).

Noise rejection: Common mode: 110dB at 60Hz, typical.

RFI resistance: Less than ±0.5%, of output span effect.

EMI resistance: Less than ±0.25% of output span effect.
Surge withstand capability (SWC) Input/Output terminations rated per ANSI/IEEE C37.90-1978. Unit is tested to a standardized test waveform that is representative of surges (high frequency transient electrical interference), observed in actual installations.

  • Excellent accuracy and stability ensure reliable measurements in harsh industrial environments.
  • 1500V AC peak isolation (250V AC or 354V DC continuous) prevents ground loops.
  • RFI and EMI resistance minimize the effects of environmental noise.
  • Calibration is independent of the load to eliminate load compensation adjustments
  • Zero and span adjustment enable precise calibration.
  • Compact, 1-inch wide housing uses less space for easier installation in control panels.
  • Input current sense resistor simplifies field diagnostics
  • Operating temperature range -13 to 185°F (-25 to 85°C)
How to Select the Right Isolator Application Note
The ins and outs of isolation: A guide to selecting the right isolator Acromag manufactures a variety of isolators to provide a cost-effective solution for many applications. The primary function of the isolator is to eliminate ground loops that may exist between two or more instruments. A classical application isolates the control room equipment (computers,...
How to Choose a 4-20mA Isolator Application Note
Very often the simple task of choosing an isolator requires more than just comparing the number of channels and the cost per point. To help you with this exercise, here are a few concepts to know when specifying a 4-20 mA isolator. The lowest cost approach is a Two-Wire System using Output Loop Powered devices...
WHITEPAPER: The Importance of Signal Isolation (Log in to view the file)
Learn How to Recognize the Need for Isolation Learn how to recognize the need for isolation in this easy to understand white paper. This paper covers the basic aspects of electrical isolation, what it does for you, why you need it, and how we test for it. Common Methods Of Signal Isolation So the real...

Specifications

Manuals

270i Series User Manual (Log in to download the file)

Additional information

Weight 16 oz
Dimensions 3 × 1 × 3.2 in
Part Number

270i-20MA-N4-NCR: NEMA 4, water-tight, holds two; no certification/approval required, 270i-20MA-XP-DT1: explosion-proof NEMA 4 holds one; CSA approval, Div 2 hazardous locations, 270i-20MA-ST-DT1: SNAPTRACK mount; CSA approval, Div 2 hazardous locations, 270i-20MA-SM-DT1: surface-mount; CSA approval Div 2 hazardous locations, 270i-20MA-N12-NCR: NEMA 12, oil-tight, holds two; no certification/approval required, 270i-20MA-DIN-NCR: DIN rail G or T mount; no certification/approval required, 270i-20MA-XP-NCR: explosion-proof NEMA 4 holds one; no certification/approval required, 270i-20MA-ST-NCR: SNAPTRACK mount; no certification/approval required, 270i-20MA-SM-NCR: surface-mount; no certification/approval required, 270i-20MA-N4-DT1: NEMA 4, water-tight, holds two; CSA approval Div 2 hazardous locations, 270i-20MA-N12-DT1: NEMA 12, oil-tight, holds two; CSA approval Div 2 hazardous locations, 270i-20MA-DIN-DT1: DIN rail G or T mount; CSA approval Div 2 hazardous locations

Product Series

FlatPack Series

  • Description

    The 270i accepts a process current input and provides an isolated 4 to 20mA process current output signal. Power is received from the input signal current.

    These isolators use transformer isolation to effectively break the electrical path between the transmitted signal and the receiving device. This eliminates ground loops, reduces noise, and helps protect against transients for more accurate and reliable measurements.

    This product is also extremely easy to install. All units are factory calibrated for loads up to 600 ohms to eliminate any need for load trim adjustments.

    Approvals
    CSA
    Class I; Division 2; Groups A, B, C, D

    270i Loop Powered Isolator Performance

    Input

    Input Range: 4 to 20mA input. Power is derived from the input signal loop. Input current should be limited to less than 50mA to prevent damage to the isolator. In the event of an open output circuit, the input loop voltage drop is limited to 20V, nominal. Isolator has reverse polarity protection.

    Zero and span: Zero and span trim adjustments utilize 22-turn potentiometers accessible from front of the unit.

    Input voltage drop: The voltage drop is a function of the input current and load resistance and is calculated as follows:
    Input Voltage Drop = 5.4V DC + (0.0216A x RLOAD
    Example (RLOAD = 250 ohms):
    Input Voltage Drop = 5.4V DC + (0.0216A x 250 ohms) = 10.8V DC.

    Current sense resistor: A built-in 10 ohm (±0.1%) resistor can monitor input current to the isolator. Wiring to the isolator’s input terminals determines if this resistor is included in the current loop. Use of this resistor provides a test signal of 40 to 200mV, representing 4 to 20mA.

    Output

    Output Range: 4-20mA DC output.
    A. For RLOAD from 50 to 600 ohms, connect RLOAD between Output (+) and Output (-) terminals.
    B. For RLOAD from 0 to 50 ohms, connect RLOAD between Output (S) and Output (-) terminals. For
    optimum performance at low values of RLOAD, the isolator has a built-in pad resistor of 50 ohms.

    1. Input Voltage Drop (input sense resistor not used): VDROP = 5.4V DC + (0.0216A x (RLOAD + 50 ohms))
    2. Input Voltage Drop (input sense resistor used) VDROP = 5.6V DC + (0.0216A x (RLOAD + 50 ohms))

    Accuracy: ±0.1% of output span. Error includes the combined effects of isolator repeatability, hysteresis, terminal point linearity and adjustment resolution.

    Load resistance effect: Less than ±-0.1% of output span as load resistance is changed over entire range. Allows use of isolator, within resistance load range, without the need to recalibrate the isolator for a particular load.

    Output ripple: Less than ±0.1% of the maximum output span.

    Bandwidth: -3dB at 3Hz, typical.

    Response time: For a step input, the output reaches 98% of output span in 180mS, typical.

    Environmental

    Ambient temperature range
    Operating: -13 to 185°F (-25 to 85°C).
    Storage: -40 to 185°F (-40 to 85°C).

    Ambient temperature effect: Less than ±0.006% of output span per °F (±0.01% per °C) over the ambient temperature range for reference test conditions. This specification includes the combined effects of zero and span over temperature.

    Isolation: The input and output circuits are isolated from each other for common-mode voltages up to 250V AC, or 354V DC off ground, on a continuous basis (will withstand 1500V AC dielectric strength test for one minute without breakdown).

    Noise rejection: Common mode: 110dB at 60Hz, typical.

    RFI resistance: Less than ±0.5%, of output span effect.

    EMI resistance: Less than ±0.25% of output span effect.
    Surge withstand capability (SWC) Input/Output terminations rated per ANSI/IEEE C37.90-1978. Unit is tested to a standardized test waveform that is representative of surges (high frequency transient electrical interference), observed in actual installations.

  • Features & Benefits

    • Excellent accuracy and stability ensure reliable measurements in harsh industrial environments.
    • 1500V AC peak isolation (250V AC or 354V DC continuous) prevents ground loops.
    • RFI and EMI resistance minimize the effects of environmental noise.
    • Calibration is independent of the load to eliminate load compensation adjustments
    • Zero and span adjustment enable precise calibration.
    • Compact, 1-inch wide housing uses less space for easier installation in control panels.
    • Input current sense resistor simplifies field diagnostics
    • Operating temperature range -13 to 185°F (-25 to 85°C)
  • Tech Papers

    How to Select the Right Isolator Application Note
    The ins and outs of isolation: A guide to selecting the right isolator Acromag manufactures a variety of isolators to provide a cost-effective solution for many applications. The primary function of the isolator is to eliminate ground loops that may exist between two or more instruments. A classical application isolates the control room equipment (computers,...
    How to Choose a 4-20mA Isolator Application Note
    Very often the simple task of choosing an isolator requires more than just comparing the number of channels and the cost per point. To help you with this exercise, here are a few concepts to know when specifying a 4-20 mA isolator. The lowest cost approach is a Two-Wire System using Output Loop Powered devices...
    WHITEPAPER: The Importance of Signal Isolation (Log in to view the file)
    Learn How to Recognize the Need for Isolation Learn how to recognize the need for isolation in this easy to understand white paper. This paper covers the basic aspects of electrical isolation, what it does for you, why you need it, and how we test for it. Common Methods Of Signal Isolation So the real...
  • Specs & Data Sheets

    Specifications

    Manuals

    270i Series User Manual (Log in to download the file)

  • Additional information

    Additional information

    Weight 16 oz
    Dimensions 3 × 1 × 3.2 in
    Part Number

    270i-20MA-N4-NCR: NEMA 4, water-tight, holds two; no certification/approval required, 270i-20MA-XP-DT1: explosion-proof NEMA 4 holds one; CSA approval, Div 2 hazardous locations, 270i-20MA-ST-DT1: SNAPTRACK mount; CSA approval, Div 2 hazardous locations, 270i-20MA-SM-DT1: surface-mount; CSA approval Div 2 hazardous locations, 270i-20MA-N12-NCR: NEMA 12, oil-tight, holds two; no certification/approval required, 270i-20MA-DIN-NCR: DIN rail G or T mount; no certification/approval required, 270i-20MA-XP-NCR: explosion-proof NEMA 4 holds one; no certification/approval required, 270i-20MA-ST-NCR: SNAPTRACK mount; no certification/approval required, 270i-20MA-SM-NCR: surface-mount; no certification/approval required, 270i-20MA-N4-DT1: NEMA 4, water-tight, holds two; CSA approval Div 2 hazardous locations, 270i-20MA-N12-DT1: NEMA 12, oil-tight, holds two; CSA approval Div 2 hazardous locations, 270i-20MA-DIN-DT1: DIN rail G or T mount; CSA approval Div 2 hazardous locations

    Product Series

    FlatPack Series