Measurand
Frequency Range
Display Rate
Sample Rate
Vibration acceleration
0,2 Hz – 10 kHz
5.6 s
23.438 kHz
Vibration acceleration
3 Hz – 1 kHz
1.4 s
2.930 kHz
Vibration acceleration
1 kHz – 10 kHz
1.4 s
23.438 kHz
Vibration velocity
2 Hz – 1 kHz
1.4 s
2.930 kHz
Vibration velocity
10 Hz – 1 kHz
1.4 s
11.719 kHz
Vibration displacement
5 Hz – 200 Hz
2.8 s
2.930 kHz
3.2. Vibration Acceleration
The VM24 has the following frequency ranges for vibration acceleration:
•
0.2 Hz to 10 kHz: full frequency bandwidth of the accelerometer
•
3 Hz to 1 kHz: lower frequency acceleration
•
1 kHz to 10 kHz: high frequency vibration only
In this way specific signal components can be measured whilst others are attenu -
ated. For example, when taking measurements on machines, at a frequency of 1 kHz
to 10 kHz predominantly the running noise of rolling bearings can be monitored,
whilst vibrational unbalances are attenuated.
3.3. Vibration Velocity
Measuring vibration velocity is a common procedure for assessing the running smooth-
ness of rotating machines. Vibration velocity, commonly known as vibration severity,
represents the energy expenditure of occurring vibrations. Vibrations are caused by rota-
tional unbalances, for example as a result of loose screws, bent parts, worn or slack bear-
ings or dirt residues on the fan blades. Often several factors have a mutually reinforcing
effect. Besides rotating machines, the measurement procedure is also suitable for recipro-
cating machines.
The specifications of vibration velocity measuring instruments are described in
ISO 2954. In the ISO 2954 a band filter for the vibration velocity of 10 to 1000 Hz is de-
fined. The displayed value of the vibration severity is the true RMS.
5
Figure 3: Frequency response curves for acceleration
0,1
1
10
100
1000
10000
100000
0,001
0,01
0,1
1
10
a: 0,2Hz-10kHz
a: 3Hz-1kHz
a: 1kHz-10kHz
Hz
m
/s
²