Early warning systems for factories
To measure vibrations we may measure displacement, velocity or acceleration using displacement sensors, velocity sensors or accelerometers. Among them, Accelerometer sensor is commonly used for vibration analysis and is capable of measuring machine accelerations, tilt, and vibration or shock. Condition monitoring and Predictive maintenance are the 2 relevant vibration monitoring applications that we have developed for industrial monitoring in factories.
MEMS is the latest technology of microscopic devices, particularly those with moving parts. With the advancement in electronic chip design, industrial IOT, MEMS sensors are preferred over Piezoelectric Sensors.
- Low cost (Eg..MEMS- 50$ , Piezoelectric- 1000$)
- Higher Accuracy & Ultra-low noise
- High Frequency (not as high as piezo, but more than enough for what we need)
- Compatible with IoT platforms
- Low Power (can work on battery)
- Based on smart factory concept
In an earlier IOT blog post, we have detailed about the need to monitor vibration of equipment to reduce breakdowns and unscheduled maintenance. Here are some of the factors which determines accuracy in machine behaviour.
Sensitivity is the most important parameter of an accelerometer which means show accurate is the sensor output . It is specified in mV/G. (Eg. 1 mV/G, 100 mV/G ).
Range / Vibration Amplitude
Range means the range of vibration amplitudes which the accelerometer is capable to measure and is expressed like +-2g.
Range of frequencies which the sensor can capture. A motor working at 1500 rpm (normal) require a sensor with minimum 1500 rpm bandwidth to capture abnormal vibrations.
Number of Axis
In order to detect vibrations sensors should be deployed on a proper machine point mounted in X,Y, or Z axis directions. In the market, sensors to capture vibrations at only 1 axis or all 3 axis at same time are present.
In order to capture ultra low motions in machines, ultra noise sensors are used. Piezoelectric sensors are widely used in industry due to low noise but in second generation, MEMS sensors with lower noise magnitude compared to Piezo electrics is been recently developed and we have implemented these solutions in our industrial monitoring and anomaly detection products.
This means how many records the sensor captures in one second and it’s expressed in Hz. For a 1500 rpm motor sampling frequency should be at least 50 Hz.
It determines how to mount sensor to the target machine surface. 4 mounting methods include: Handheld or probe tips, Magnetic, Adhesive and Stud mount. Stud mount is used for permanent and other mounts for temporary installations.The various mounting methods affect the measurable frequency of the accelerometer. Our condition monitoring solutions for factories are a mix of magnetic and adhesive based.