4-20mA Loop-Powered Isolators, 2-Wire

Models get power from the 4-20mA output or input loop (sinks or sources current). Typical uses are as a current repeater or to drive resistive loads. 651T and 250T models 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. 670T and 270i models 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.

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    TT236: Current/Millivolt Input Two-Wire/Three-Wire Transmitter

    • Multi-range ±20mA or ±500mV input
    • 4-20mA ouput (sink/source)
    • 12-32 V DC loop/local power
    $185
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    270i: Isolator; Input Loop Power

    • 4-20mA DC input
    • 4-20mA DC output
    • 1500V AC peak isolation DC prevents ground loops
    $450$645
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    651T, 652T: Multi-Channel, Two-Wire Isolators

    • Input / Output Ranges: 4 to 20mA DC input; 4 to 20mA DC output
    • Power Requirement: 12 to 36V DC (loop-powered) Two-wire transmitter
    • Approvals: CE marked. UL, cUL listed Class I, Division 2, Groups A,B,C,D
    $175$260
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    671T, 672T, 674T: Multi-Channel, Two-Wire Isolators

    • 4 to 20mA DC input
    • 4 to 20mA DC output
    • Loop-powered
    $175$340
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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
    $405$450
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More 4-20mA Isolators Information

651T and 250T models 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.

670T and 270i models 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.

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