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

A 4-20 mA loop represents an analog signal used for transmitting process variable data. In instrumentation and control systems, the 4-20 mA current loop is widely adopted because it provides a continuous signal that can vary smoothly across a specified range. The range from 4 mA to 20 mA corresponds to the measurement of a physical process variable, such as temperature, pressure, or flow rate.

Using this configuration, the minimum signal level starts at 4 mA to represent the lowest measurable value of the process, and 20 mA corresponds to the maximum measurable value. This range not only facilitates accurate measuring and control but also allows for easy detection of signal issues. For instance, if the current drops below 4 mA, it typically indicates a fault condition or a broken connection, thereby providing additional diagnostic capabilities.

This continuous analog representation is crucial in many industrial applications where precise monitoring and control of process variables are necessary for efficient operations.