What is the difference between 2 wire 3 wire and 4 wire transmitters?

Last Updated on May 25, 2022 by Krunal Shah

Wiring a process instrument is quite hectic. Because, before you wire it you should know whether the transmitter is 2-wire, 3 wire or 4-wire. Also, the internal wiring of PLC analog input depends on the type of transmitter wiring.

Also, it is one of the most important selection criteria for process instruments as well.

So in this article, I would tell you the difference between all the three wiring types along with their pros and cons.

2-Wire Transmitter

This is one of the simplest wiring types as it only has two wires. In this configuration supply power and 4-20 mA signal uses two-wire loop connections. Either the transmitter or the receiver would provide the power supply to the loop. However, a separate power supply is also available as an option.

3-Wire Transmitter

The transmitter and receiver share common 0 V DC lines. 4-20 mA is supplied by the transmitter to the PLC module. 3rd wire is used to connect common 0 V DC.

4-Wire Transmitter

The transmitter uses a separate 24 DC power supply. The 4-20 mA flows through two separate cables.