Online Condition Monitoring System for Shaft Generators

Prediction of failures for crucial machinery on the vessel + higher vibration values on Shaft Generators
The client needs to have a system that can monitor vibrations and what is more find the source of the problem. Info Marine Company came up with the solution of an Online Monitoring System that can display overall values of vibrations in real-time and record data for further analysis of FFT spectrum.
Overall values of vibrations indicate that there might be a problem within machinery but we cannot say what is the source of this problem. In this case, we need more advanced methods. The provided system allows to collection vibration data for a longer period of time – trend those values. What is more, crew could see vibration readings in real-time. Last but not least we could record data that later on can be analysed by Info Marine company. Alarms (based on ISO recommendations) could be set, extending those values to trigger the automatic recording of necessary data for FFT spectrum analysis. Anytime those files could be sent to Info Marine company for more advanced analysis.
Dashboard view on vibration values
Recorded FFT spectrum

The system monitors two shaft generators. Each of them has two 3-axial vibration sensors and one RPM sensor for more precise rotational speed measurements. Sensors are connected to a data acquisition device within a metal junction box. Then via VDSL protocol data is transferred to the computer inside the Engine Control Room. The laptop has installed dedicated software for the Condition Monitoring System.

 

Vibration sensor mounting
Metal junction box assembling

In other online condition monitoring systems, the main problem is that they cannot provide a proper analysis of the source of potential failure. Info Marine found a solution that expects the least from the crew and the system is operating by itself. Crew from time to time just need to send data to the company.
After the implementation of the system, the alarm was immediately triggered on the Drive End of one of the Generators. Service engineers collected the recordings and later on they were analysed in detail.
Here are the measured Velocity and Envelope values:

Table 1. Shaft Generator vibrations result. Range (10 – 1000Hz)

A brief look at the summary for this report:

Recommendation
Alignment needs to be corrected. Next measurements after work should be sent for analysis.

To summarize we created a system that can monitor vibration data in real time and allows for more advanced analysis. After implementation, we found problem with alignment. In this case, two machines were monitored but this type of system can be easily extended for many more. We are not limited by distance and space (in one room we just need one metal box then all data is transferred by one cable). Even though the installation could contain machinery on the bow and aft of the vessel, the system can be easily and rapidly implemented.