Created with Sketch. Created with Sketch.

4-20 mA

The purpose of the 4-20 mA analog current loop is to transmit the signal from an analog vibration sensor over a distance in the form of a current signal. Our accelerometers output a low voltage (mV) which is proportional to the overall vibration of the equipment or machinery they are monitoring. This is converted to a proportional output current, with the range of 4-20 mA (4 mA normally representing the sensor’s zero-level output, and 20 mA representing the sensor’s full-scale output). Only two wires are required to send the current signal and also supply power to the sensor. A loop supply voltage is used to power a remote sensor. The remote sensor regulates the loop current such that the loop current represents the value of the parameter being measured by the sensor. A series resistor RL at the loop power supply converts this current to a voltage that can be used by the process monitor/ controller to record or distribute the parameter being measured.