TE CONNECTIVITY SENSORS / WHITE PAPER
Predictive Maintenance with Vibration Sensors
PAGE 4
VARIABLE CAPACITANCE VIBRATION SENSORS
Variable Capacitance (VC) sensors derive the acceleration measurement from a change in capacitance of a seismic
mass moving between two parallel capacitor plates. The change in capacitance is directly proportional to the applied
acceleration. VC accelerometers require an IC to be closely coupled to the sensing element to convert the very small
capacitance changes into a voltage output. This conversion process often results in poor signal to noise ratio
and limited dynamic range
The VC sensors are typically manufactured from silicon wafers and are fabricated into miniature MEMS
(Micro-Electro-Mechanical-Systems) chips.
TECHNOLOGY COMPARISON CHART
For industrial condition monitoring and predictive maintenance applications the following vibration specification
parameters are considered critical to ensure long term reliable, stable and accurate performance.
• Wide Frequency Response
• Measurement Resolution and Dynamic Range
• Long Term Stability with Minimum Drift
• Operating Temperature Range
• Packaging Options and Ease of Installation
• Sensor Output Options
In the following paragraphs, these critical performance specifications were compared for typical piezo-electric
condition monitoring accelerometer and a wide bandwidth MEMS variable capacitance accelerometer also
marketed for condition monitoring applications. Both accelerometers had a FS (Full Scale) range of ±50g.
FREQUNCEY RESPONSE TABLE
