[FAQ] What is a 4-wire 4-20mA current transmitter?

Similar to 3-wire transmitters, 4-wire transmitters have a local power supply. However, 4-wire transmitters have separate paths for the power current and signal current, and the receiver does not share a common ground with the transmitter supply. The attached blog series will provide an overview and explain the isolation schemes possible with 4-wire systems.

4-Wire Current-Loop Sensor Transmitters

Designing output isolated 4-wire sensor transmitters

How to design power-isolated 4-wire sensor transmitters

How to design fully isolated 4-wire sensor transmitters