BISOPE series 31 Relation between type of vibration sensor and unit of ...

BISOPE series 31- Relation between type of vibration sensor and unit of amplitude (displacement, velocity, acceleration) Vibration measurement and evaluation

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If the desired 'unit' of vibration is selected as a result for the evaluation, the next step is to select an appropriate 'sensor'. First of all, it is necessary to check whether contact attachment is possible at the location to be measured... or whether the attachment method is appropriate. For example, in the case of high frequency (more than 5000Hz), the magnetic attachment method is not appropriate, and if you want to measure the behavior of an axis, it is difficult to use a contact sensor. Also, if you try to measure the speed and measure 5 Hz using a coin type speed sensor, you will get an amplified error signal. This is because the characteristics of each sensor are different depending on the amplitude band, frequency band, resonance band, etc.

 

​Selection of displacement, velocity, and acceleration sensors such as amplitude units

Since the output voltage or current is proportional to each unit, the selection of the unit is not very different from the selection of the sensor. Sensors mainly used for diagnosing and monitoring equipment

 

1. Eddy current type displacement sensor (Proximity) that directly measures the behavior of a shaft supported by a sleeve bearing in a non-contact manner.

2. Accelerometer, which propagates shaft vibration to rolling bearing and measures it indirectly by contact method outside the bearing housing (indirectly transmitted to the housing by impact of the bearing connected to the shaft)

3. There is a velocity transducer that works without power.

However, among these, the speed sensor is very precise, but has a weakness limited to the range of 10 to 1000 Hz because it has a natural frequency in the upper and lower frequencies, which is why displacement sensors and acceleration sensors are widely used. (If it is out of this frequency range, an erroneous or amplified value is output.)

A sensor (transducer) is one of the components of a system that is mainly used by companies that use sensors to research, diagnose or manufacture monitoring equipment. Since the manufacturer has selected a sensor that fits a specific principle, the manufacturer has accumulated a lot of engineering grounds for this. In many cases, the level of engineering is considerably deeper than that of academia because it must be required and the reliability of the measurement needs to be verified.

Above all, this principle can be considered as the most basic sensor selection method. The reason why a displacement sensor is called a displacement sensor and an acceleration sensor is called an acceleration sensor is that each sensor generates an electrical output 'proportional to the amplitude unit'. It's because you do it. For example, since the value converted to displacement by outputting acceleration vibration with an acceleration sensor and integrating twice is not very accurate (especially when it is not a sine wave), it is better to measure acceleration vibration with an acceleration sensor, and displacement vibration It is basic to measure with a displacement sensor. However, there are cases where it is absolutely necessary to evaluate the health of a machine or the vibration of a building with the 'velocity' value, which is used as the most evaluation unit in academia and industry, so this only allows integration from the acceleration sensor once. Because the speed sensor isn't cool...

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