IEC 60381-2: Process Control Analogue Signals — The 4-20mA Current Loop Standard Signal Range

Why Industrial Sensors Use 4-20mA, Not 0-10V — The Current Loop Noise Immunity Advantage

IEC 60381-2:1978 specifies process control analogue signal standard ranges — 4-20mA DC current loop. Compared to voltage signals (0-10V), current loops offer three advantages: (1) EMI immunity (low-impedance loop does not pick up noise); (2) no voltage-drop error over long distances (current is equal everywhere in the loop); (3) inherent open-circuit detection (0mA=fault, 4mA=zero scale).

TNLab — The 4-20mA current loop is the “gold standard” of industrial sensor communication — reliably operating for 50 years.