4-20mA Loop-Powered Isolators, 2-Wire
These 2-wire 4-20mA loop-powered isolators get their 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. These 2-wire 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. These modules 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.Showing all 7 results
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TT236: Current / milliVolt Input Two-Wire Transmitter
- Multi-range ±20mA or ±500mV input
- 4-20mA ouput (sink/source)
- 12-32 V DC loop/local power
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DT236: Current / milliVolt Input Two-Wire Dual Transmitter
- Dual channels
- ±20mA, ±500mV inputs
- 4-20mA outputs (sink/source)
- 7-32V DC loop power
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VPM2000 Series: Loop-Powered Isolator / Alarm with Display
- Loop-powered Process Meter
- 4-20mA input/output
- Solid-state relays
- Non-incendive, intrinsically safe
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651T, 652T: Multi-Channel, Two-Wire Isolators
- DC current input
- Single/dual-channel DC-powered isolators
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671T, 672T, 674T: Multi-Channel, Two-Wire Isolators
- DC current input
- Single, dual, or quad I/O loop-powered isolators
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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
4-20mA Signal Isolators Continued

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:
- Why Do I Need Electrical Isolation? (Whitepaper)
- How to Choose a 4-20mA Isolator (App note)
- Why You Need USB Isolation for Industrial I/O (Whitepaper)
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.