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Case
study
Motor
Bearing Failure
Abstract:
An inner race fault was successfully detected in the bearing of a motor
for a cooling water pump.
The
following case study was taken from a regular survey of plant located at
the site one of our customers.
Background:
The aptGroup
carries out regular vibration surveys at the customer's
plant. The pump that is the subject of this study circulates cooling water
to other machines.
Method:
A portable data collector/analayser and accelerometer were used
to take the vibration measurements. The accelerometer was attached to the
machine using a magnet.
Measurements of velocity (0-600 Hz), acceleration (0-5000 Hz) and
acceleration enveloping (5 - 40 kHz) were made.
Results:
Following a survey, a fault was detected in the drive end bearing of the
motor. The vibration spectrum (fig 1) indicated that an inner race fault
was present in the bearing.
When
the motor was overhauled, the inner race of the bearing was found to be
damaged (fig 2), as indicated by the vibration data.
Figure
1: Vibration Spectrum from DE Bearing
Figure
2: Inner Race, showing damage
Conclusions:
Vibration monitoring successfully detected a damaged bearing in this
motor. Corrective action was undertaken well before a failure occurred.
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