Comparison of the signal characteristics measured by a MEMS and a Piezoelectric accelerometers

This study is dedicated to verifying the performance of a MEMS accelerometer when used for machine condition monitoring based on vibration analysis. The performance of the MEMS accelerometer was compared to that of a piezoelectric sensor, traditionally used in this type of analysis. This goal was reached by measuring the RMS, Kurtosis and Crest levels of the signal obtained by the MEMS sensor against those obtained by the piezoelectric sensor under the same excitation parameters. Both the piezoelectric sensor and the MEMS circuit board were mounted on a special device attached to a shaker. The sensors were submitted to vibrations of 0.5g, 1g and 2g RMS on a frequency ranging from 1Hz up to 2500Hz on steps of 20Hz. The results show that the readings of the MEMS sensor present a maximum deviation of 6.6% when compared to the piezoelectric sensor. It was possible to conclude that a great portion of the deviation encountered was due to the dynamic characteristics of the mounting device and the fixation conditions of the MEMS sensor on this device