X90 mobile modules
X90 mobile system User's manual V 1.20 - Translation of the original manual
259
m
u
r
u
S
e
m
s
+ m
u
Rotation
of axis
ω
Figure 92: Representative sketch of an imbalance
Imbalance leads to vibrations and increased wear, particularly at high speeds, which is why counterweights are
applied to compensate for this as counterbalance. In practice, it is very rarely possible to fully compensate for this,
meaning every rotating body has some residual imbalance.
The centrifugal force caused by imbalance is dependent on the square speed and thus has a more significant
effect at higher speeds (higher speed frequency). On a spectrum, therefore, the frequency line denoting speed
is significantly higher.
Failure mode
Frequency in
raw signal spectrum
Frequency in
envelope spectrum
Comment
Imbalance
1 x fn
-
Only severe imbalance causes peaks in the speed that show up
in the envelope spectrum.
fn
... Nominal speed
Information:
The module can only measure the intensity of the imbalance, not its position on the shaft. For this
reason, it cannot be used for balancing.
