4–20 mA
The standard analogue instrument signal. 4 mA represents 0% of range and 20 mA represents 100%. Because the live zero is 4 mA and not 0 mA, a broken wire reads 0 mA and is instantly distinguishable from a genuine zero reading.
Piping inspection and supervision, explained from scratch
The standard analogue instrument signal. 4 mA represents 0% of range and 20 mA represents 100%. Because the live zero is 4 mA and not 0 mA, a broken wire reads 0 mA and is instantly distinguishable from a genuine zero reading.