Figure 1 - Typical Spectrum Showing
Indications Of Eccentric Rotor. Similar To Eccentric Stator. Some
Cases May Exhibit The Sidebands Seen Here; Others May Propagate Strictly
At 2x Line Frequency.
|
Eccentric
Rotor Symptoms:
-
High amplitudes
at 2 x FLine.
-
Possible
sidebands around 2x line frequency and/or 1x rpm.
Recommended Actions:
-
Check for soft
foot and repair.
-
Check alignment
and repair.
-
On-line current
analysis to assess condition and determine severity.
-
Live with it or
buy a new motor.
NOTE: It
is important to realize that vibration at 2 x FLine is a normally occurring
vibration. The effect on the bearings is no greater or less than the
same amplitude due to unbalance. Do not
over-react. |
| NOTE:
Do not confuse the presence of a running speed harmonic with a pole pass
frequency sideband. By definition, a running speed harmonic will
always
be separated from 2 x FLine by pole pass frequency. |
