The Field Tools Loop Power provides portable power to loop-powered 2-wire transmitters for commissioning and testing. It's a fully contained power source that takes the low voltage from three "AAA" alkaline batteries and increases it to a highly filtered 24 volt power source. Loop Power is easy to use, includes all connection leads, and makes it simple to attach your HART protocol modem to the loop.

Brochure (PDF)
Manual (PDF)

Loop Power Block Diagram

Using batteries as the power source eliminates isolation concerns as well as the need for a power connection to AC or a USB port. The voltage conversion is done using a high efficiency switching DC-DC converter to maximize battery life - over 6 hours at 12mA.

"Quick simple power for transmitter field calibrations and testing."

Connecting is quick and simple. Clip on the two mini-grabber clips to the power input of your transmitter and push the connect button. A single connect/disconnect button enables or disables the 24 volt output while a status LED indicates the active operating mode. Loop Supply automatically powers down if left active to save battery life. If the batteries become low, the status LED will flash while connected to remind you to replace them soon.

"connect the two power leads and press a button
to supply 24 volts to 4-20mA loop transmitters."

"To measure loop current plug the test leads into your DC milliamp meter"

To measure loop current plug the milliamp meter test leads directly into a standard DC current meter. There's no need to break the loop to attach the meter because internal circuits route the loop current through the meter when it's connected. If the load current exceeds 30mA, or is shorted, the output will quickly disconnect. To restore the output simply remove the excess load or short and press the connect button. 

24V Supply HART modem clips

Mini-grabber clip points make attaching a HART modem or HART calibrator quick and simple. A 250 ohm loop resistor is included internally so no external connections or jumpers are needed.

Using the Field Tools Loop Supply will simplify your 2-wire transmitter commissioning, calibration, and testing while eliminating time wasted troubleshooting your calibration setup. Simplify your calibrations with a Field Tools Loop Power Supply today.





  • Highly filtered 24 volt power source for 4-20mA loop transmitters

  • Up to 30mA capacity, perfect for 4-20mA devices

  • Battery powered - eliminates galvanic isolation concerns

  • Includes an internal 250 ohm loop resistor to allow for HART protocol

  • HART modem mini-grabber clip points for easy modem connection to the loop

  • All connection leads included - no need for extra test leads and alligator clips

  • Long battery life, greater than 6 hours continuous at 12mA load

  • Status LED indicates when battery is getting low

  • Able to maintain output even with weak batteries to maximize battery life

  • Uses easy to find, low cost, standard “AAA” alkaline batteries

  • Short circuit protection disconnects the output if shorted or over-current detected (>30mA)


Optional soft case is available.  Part Number 160-0001