What is Bias Voltage in Vibration Sensors?

Vibration Sensors are used to measure Vibration Levels of Machines for Monitoring, Protection and Analysis. They are thus a crucial element of a Vibration Monitoring or Machinery Protection System.

ICP or IEPE sensors usually require 15-30 V DC (typically 24 V DC) power input to function. This voltage is usually provided by the monitoring system to which they are connected. The return AC Dynamic Vibration Signal is accompanied by a carrier DC voltage. This carrier DC Voltage is called as Bias Voltage. For a typical 100 mV/g Vibration Sensor like IRD521 - the normal range for this Bias Voltage is 8 V DC to 16 V DC.

Monitoring the Bias Voltage provides an indication of the healthiness of the sensor and its connecting cable. If the Bias Voltage falls below 8 V DC for IRD521 - then it indicates either a loss of connection or insufficient power supply to the sensor. If the Bias Voltage rises above 16 V DC for IRD521 - it again indicates a loss of connection thereby indicating either a fault with the sensor or with the connecting cable.

So, to summarise - Bias Voltage is a carrier DC Voltage that helps check healthiness of Vibration Sensors at any given point in time. A healthy sensor is essential to good results from any Vibration Monitoring or Machinery Protection System.

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