Why using 4-20mA in industry

Why the industry standard is 4-20mA? why current signal instead of typical voltage signals?
All of that is discussed in this episode.

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[youtuuba]

Good video, but it still fails to explain a few important things:
- In series circuits, current is constant, meaning that current is the exact same at any point in that series circuit.
- Current is NOT less affected by magnetic fields than is voltage. However, if extra current is magnetically induced at one or more points in a series circuit, that same current will also flow everywhere else in the circuit. Because of this, the transmitter is 'aware' of the extra unwanted current and can thus instantly adjust the loop current to compensate. The same applies to changes in the resistance of the series circuit. This compensation would not be possible if the process signal were sent as a voltage.
- The action of the transmitter is key to the success of the current loop. It can instantly adjust its series resistance as required to regulate the loop current to the desired value. It also monitors the loop current so that it can instantly compensate for errors and outside influencing factors.
- Some current loops DO use 0-20mA. One of the advantages of using 4mA as the minimum normal value is, as the video states, to allow detection of open circuit and/or loop power supply failure. Another big reason is that always having at least the 4mA quiescent current in the loop circuit, is that this provides a small power source to operate the transmitter, as long as the transmitter is designed to never require more than 4mA. Without this quiescent current, there would need to be an additional power supply to operate the transmitter circuitry; this scenario is called "4 wire". When the transmitter is designed to operate on only the quiescent 4mA, then no additional power supply is required, and this is called "2 wire".

[mohamedklileche]

Outstanding video explanation, informative, and straight to the point . Thank you for sharing

[clems]

As a rule if thumb. I will use 0-10V within a cabinet. And always use current [4-20ma] for all field wiring or if it leaves the cabinet.

[alexlee]

for a long distance signal transmission, voltage has a drop, but current does not, thats why normally use current to transmit electric signals. As far as a voltage/current transducer(sensor) is concerned, the output signal adopts 4-20mA that's because 4-20mA is a safe signal, esp, in a coal mine, or explosive-proof sites, the spark energy caused by 4-20mA current is not enought to cause explosion.

[ahmedaliabdelrazik]

Question, Why we don't have use 1V as a minimum voltage, hence we can detect both minimum and open circuit, like 0 and 4 mA

[suradrabee]

كيف ممكن اعرف الحساسات اذا ما عليها مواصفات

[vijaykavali]

Video is so nice but we want this type of all videos in Telugu launguage