Motor Bearing Fault

Motor bearing fault detected by a Vibration Analysis inspection of an air intake fan motor

Motor Bearing Fault Detected in Air Intake Fan Motor

Motor - Coupling - FanInspection description: Vibration analysis inspection of Fan Motor Drive
Frequency of inspection: Monthly
Equipment description: Motor – Coupling – Fan running 24/7

Vibration reading (Acceleration Power Spectrum o/all value 1.14g) from the Motor Drive Bearing recorded in April 2016:

Image 1

This spectrum indicates the normal operating vibration baseline from the Motor Drive Bearing.

Vibration reading (Acceleration Power Spectrum o/all value 2.517g) from the Motor Drive Bearing recorded in May 2016:

Image 2

This spectrum indicates an increase in the overall high frequency vibration that has occurred in the last month from the Motor Drive Bearing.

Vibration reading (Demodulation Power Spectrum o/all value 1.312g) from the Motor Drive Bearing recorded in May 2016.

Image 3

This spectrum indicates impacts occurring within the Motor Drive bearing at the associated bearing fault frequencies:

Fault detection and recommended action

Fault detected: Deterioration detected of the Motor Drive Bearing of the Fan

Recommended Action: Lubrication of the Motor Drive Bearing and re-test

Vibration reading (Acceleration Power Spectrum o/all value 1.147g) from the Motor Drive Bearing recorded in June 2016:

Image 4

This spectrum indicates that lubricating the Motor Drive Bearing has masked the effect of the impacting within the bearing and hence reduced the magnitude of high frequency vibration.

Recommended action

Re-test the Motor Drive Bearing again in a month

Vibration reading (Acceleration Power Spectrum o/all value 2.977g) from the Motor Drive Bearing recorded in July 2016:

Image 5

This spectrum indicates that despite the initial positive effect of the lubrication, a month later the overall high frequency vibration has once again returned to pre-lubrication levels from the Motor Drive Bearing.

Vibration reading (Demodulation Power Spectrum o/all value 1.186g) from the Motor Drive Bearing recorded in July 2016.

Image 6

This spectrum once again indicates impacts occurring within the Motor Drive bearing at the associated bearing fault frequencies. This confirms that the bearing needs to be replaced.

Action completed

Motor Drive Bearing was replaced in late July 2016

Vibration reading comparison (Demodulation Power Spectrum) from the Motor Drive Bearing recorded in May & July 2016 pre-replacement (middle and bottom readings) and in Aug 2016 (top reading) post-replacement.

Image 7

This spectrum indicates that the previously highlighted impacts occurring within the Motor Drive bearing are no longer present in Aug 2016 after the bearing was replaced.

Vibration trend data from April 2016 to Aug 2016

Vibration reading (Acceleration Power Spectrum o/all value 1.306g) from the Motor Drive Bearing recorded in Aug 2016:

Image 8

This spectrum indicates that the overall high frequency vibration has reduced by 56% following replacement the Motor Drive Bearing.

Image 9

Summary of vibration trend (Acceleration Power Spectrum) from the Motor Drive Bearing from Aug 2015 to Aug 2016.