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4-20mA Signal Isolators

Acromag offers the industry’s best selection of 4-20mA signal isolators. Multi-channel 2-wire, 3-wire, and 4-wire isolators and isolated transmitters with AC, DC or loop-powered operation. Also offered is a loop-powered isolator with display (panel meter). Optical or galvanic isolation eliminate ground loop errors, reduce noise, and block high voltage transient surges. All Acromag isolators will withstand 1500V AC for 60 seconds and provide continuous 250V AC or 354V DC common-mode protection of your precious equipment. Acromag features solve many tough problems. Our multi-channel modules reduce costs and save space. Browse our selection below.

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    340i: DC-Powered Isolator

    • 4 to 20mA DC input
    • 4 to 20mA DC output
    • 10-36V DC power
    • 1500 AC peak isolation prevents ground loops
    • Calibration is independent of the load to eliminate load compensation adjustments
    The 340i accepts a process current input and provides an isolated 4 to 20mA process current output signal.
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    250T-DC, 350T-DC, 450T-DC: Analog Transmitter; AC-, DC- or Loop-Powered, DIN Rail-Mount

    • DC voltage or DC current input
    • DC voltage or DC current output
    • Loop or DC or AC power
    • Excellent accuracy and stability ensure reliable measurements in harsh industrial environments. Input isolated from output/power
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    270i: Input Loop-Power Isolator

    • 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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    330i: DC-Powered Isolator

    • 4 to 20mA DC input
    • 4 to 20mA DC output
    • 10-36V DC power
    • Three-way isolation
    Series 330i isolators provide 3-way isolation and do not require re-calibration for different loads. They accept a 4 to 20mA process current input and provide a 3-way isolated process current output signal.
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    430i: AC-Powered Isolator

    • 4 to 20mA DC input
    • 4 to 20mA DC output
    • 115V AC or 230V AC power
    • Three-way isolation
    • Zero and span adjustment enable precise calibration
    Series 430i isolators provide 3-way isolation and do not require re-calibration for different loads. The 430i accepts a 4 to 20mA process current input and provide a 3-way isolated process current output signal.
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4-20mA Signal Isolators Continued

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Signal Isolators For Signal Conditioning

As your I/O experts, Acromag is here to help! Below are three of our most popular application notes and whitepapers related to our signal isolators. Many times choosing the right isolator requires more than just comparing the number of channels and the cost per point. Find more application notes, white papers and support here: https://www.acromag.com/support/

Top 3 Ethernet Industrial Isolation Papers:

Some signal isolators are ideal for applications that require an isolator with a power supply in series with the output signal. Power is obtained from the output loop. The isolator must control current draw from the power supply in the output loop which is the 4-20mA signal. Since output and power share the same two wires, this type of isolator can be placed anywhere between the field sensing device and the PLC/DCS or monitoring device. Usually, the isolator is located close to the field device. Since both the input and output signal are 4-20mA, location of the device is not critical.

Other signal isolators are useful when adding and isolating a monitoring instrument to an existing current loop. When adding a field device such as a recorder or display, no additional power source is required for the added loop or for the isolator. The isolator's output is powered by the input loop power and drives passive loads only.