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5. Examples of typical vibration measurement
The followings are the examples of VA-12 settings for some typical vibration measurements. The minimum settings
for the measurement are described.
The
input range should be set up according to the amplitude of vibration so that
an overload may not occur.
5.1 Diagnosis of unbalance and misalignment
The vibration velocity is measured to diagnose the structural defects like unbalance or misalignment. The
measurements in three directions (horizontal, vertical, and axial) are necessary to diagnosis. And the biggest
value in them is used for diagnosis.
In survey diagnosis, the root mean square values of the vibration velocity are measured by Vibration Meter Mode.
If the measured value exceeds the criterion and the judgment is abnormal, the precise diagnosis is carried out. In
this case, the defect part and the cause are investigated by Time Waveform Mode or FFT Analyzer Mode. In
unbalance condition, only a shaft rotational frequency appears, but in misalignment condition, a shaft rotational
frequency and its harmonics appear. Since the vibration velocity relates to the vibration severity which indicates
the violence of total vibration, if the vibration velocity increases, there may be some abnormalities.
Fundamental settings
High-pass filter
：
10 Hz
Low-pass filter
：
1 kHz
◆
Survey diagnosis
Analysis function
：
Vibration Meter Mode
Measurement data type
：
Velocity
◆
Precise diagnosis by time waveform
Analysis function
：
Time Waveform Mode
Measurement data type
：
Velocity
Frequency span, Number of analysis lines
：
Set up so that the time waveform can be observed
◆
Precise diagnosis by FFT analysis
Analysis function
：
FFT Analyzer Mode
Measurement data type
：
Velocity
Window function
：
Hanning window
Frequency span
：
200Hz (unbalance)
、
200Hz or 500Hz (Misalignment)
Number of analysis lines
：
Set up so that the frequency resolution becomes narrower than 1Hz
Operation type
：
It is used if necessary