EDDY-CURRENT ORBIT PLOT ANALYSIS WITH A PORTABLE VIBRATION ANALYZER

The Curtis Bay plant recycle blower M53304 has a large 1000 HP Babbitt motor and fan oil-lubricated bearings, critical to optimal plant performance.

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Multiple motor failures resulted in lost production and increased maintenance expenses. Although monitored with an online vibration system utilizing eddy-current displacement sensors, these motor failures have been an ongoing problem for a long time.

It was only resolved with detailed vibration diagnostic information from the online vibration system to help address this problem. Connecting an AMS 2140 to the motor's online vibration monitoring system enabled the plant reliability staff to obtain detailed rotor displacement peak and phase vibration data. This route-based spectral, waveform, and phase data were combined in the AMS machinery manager software in an orbit plot format to help identify faults, such as:

• Imbalance

• Bent or bowed shaft

• Eccentricity

• Shaft preload

• Resonant response

• Machinery stability

• Mechanical looseness

• Rotor rub

• Misalignment in the drive shaft

• Cracked shaft behavior

• Foundation considerations

• Oil instability (Oil whirl and Oil whip)

In this case, we can correct a dynamic misalignment.

The Challenge