Academy · Signal & Analog

Why is the 4-20 mA current loop used?

4-20 mA is the most common analog signal in industry. A transmitter converts its measured value into a current between 4 mA (low end) and 20 mA (high end).

Why current, not voltage?

In a current loop the signal does not weaken along the cable and is far less affected by electrical noise. Over long cables a voltage signal drops; a current signal stays constant.