Industrial Acceleration Sensing Transmitter Using Capacitive MEMS Accelerometer

This paper presents the overall design of an industrial vibration transmitter using Micro Electro Mechanical System (MEMS) capacitive accelerometer. It describes the accelerometer sensor interfacing circuit, rms-to-dc converter and voltage to current loop converter circuit design, calibration procedure and mounting methods. The industrial vibration transmitter output can be customized to obtain either acceleration or velocity with root mean square (rms) or peak value signal. The electronic circuit was designed to measure vibration in motion. The output of the transmitter is a current signal (4-20mA) which is proportional to input acceleration (0-10g rms). The AC coupling circuit for accelerometer sensor interfacing, RMS detector and industrial current loop converter circuit are implemented in a single printed circuit board. The prototype consists of 2 pin top connector for power input (24VDC), current output signal and stainless steel mechanical housing assembly with bottom thread connection for mounting. The loop powered acceleration vibration transmitter is employed for vibration monitoring and control applications.