The output signal(4-20ma) is returned on the same wires that powers it. the main purpose of this design is to reduce wiring cost, standrdisation of circuits, and above all, to keep all the transmitters at same ground potential. A 4 wire inst. has design flexibility to utilize any power like, 230vac, 24 vdc or 110 vac.
Similarly, what is a 4 20mA transmitter?
Transmitter: This is the device used to transmit data from a sensor over the two-wire current loop. There can. be only one Transmitter output in any current loop. It acts like a variable resistor with respect to its input signal. and is the key to the 4-20mA signal transmission system.
What do you mean by 4 20mA?
Definition of: 4-20 mA. 4-20 mA. (4 to 20 MilliAmp) A point-to-point or multi-drop circuit mainly used in the process automation field to transmit signals from instruments and sensors in the field to a controller. It sends an analog signal from 4 to 20 mA that represents 0 to 100% of some process variable.