In simple language we say that vibration is a movement or mechanical oscillation about an equilibrium position of a machine or component. Vibration is a by-product of an otherwise useful operation and is very difficult to avoid.
Vibration unit is (m/s2) or units of gravitational constant “g,” where 1 g = 9.81 m/s2. Vibration measured two type as continuous measurement of critical machine and periodic measurement of machine after a selected interval.
Why need to measure the vibration:
Following are the reason to measure the vibration
- For checking the healthiness of critical machine (Like as compressor). By analysis the trend of vibration we can find the healthiness of critical machine.
- Structural Analysis.
Here we discussed about accelerometer type vibration measurement.
Accelerometer type vibration Probe:
Accelerometers type vibration probe works on piezoelectric effect. The acceleration of the gear box is transmitted to a seismic mass inside the accelerometer that generates a proportional force on the piezoelectric crystal.
Then piezo electric crystal generates an electrical charge (mv) which is proportional to the applied force. This mv is transmitted to transmitter and then transmitter amplifies this mv and converts in 4-20 ma and send to the controller / display unit.
Also Read : Bently Nevada Vibration Probes Testing
Point to choose best Accelerometer:
- On basis of mounting
- Range of measuring vibration
- Sensitivity: This is very important point to remember.Sensitivity is the relationship between the vibration and voltage produce by accelerometer at a reference Sensitivity defined mv/G. suppose a vibration probe which sensitivity is 5mv/G then its means at 1 gram forces its produce 5 mv.
Checking the probe:
- Check the resistance of probe it should be range between kilo ohms to mega ohms or refer the vendor manual.
- Tap on the vibration probe tip and check in indicator that reading is vary or not.