What type of signal does a 4-20 mA loop convey?

A 4-20 mA loop conveys a current signal, which is fundamental in industrial applications for the transmission of sensor data. The measurement range of 4-20 mA is chosen because it provides a live zero; when no current flows (0 mA), it can indicate a failure or disconnection of the sensor. The values in this range are directly proportional to the measurement being taken, such as pressure, temperature, or flow, allowing for reliable and straightforward signal interpretation.

The use of current over voltage in signal transmission offers advantages including greater resistance to noise and signal attenuation over long distances. Additionally, since the current remains steady in response to the load, the integrity of the signal is maintained, enhancing process control and monitoring capabilities. This is an important aspect of control systems technology.