What is orbit analysis?

Orbit analysis is a tool for vibration analysis on rotating machinery, especially those machines that are permanently equipped with proximity probes for vibration measurement. The process is essentially an extension of time waveform analysis as it uses time-domain data from a pair of orthogonal probes plotted on an X-Y graph with consideration for the physical location of the proximity probes. 

 

When should I consider using Orbit analysis as part of my measurements?

Whenever the rotor movements inside a certain bearing(usually sleeve bearing) are of interest and lubrication conditions need to be investigated in order to improve machine operation and prevent premature wear and potential critical failures.

 

Ok. But what about some typical applications for a better understanding of potential use cases?

More or less in any type of turbomachinery, especially large turbines in power plants such as: hydroelectric, nuclear, thermal, gas, coal, biomass, etc. and also other types of industrial components such as: compressors, drills, generators, engines, pumps, blowers and gearboxes.

 

What is an orbit plot?

Orbit Plot displays the movement of the rotor inside a sleeve bearing. Dewesoft Orbit plot supports different advanced features such as: clearance circle, relative or absolute scaling, display of history data defined in either time or revolutions and more.

 

What is a polar plot?

polar plot is a single display in a polar plane displaying amplitude vs. angle at certain RPM or time values. Dewesoft Polar plot features also rotation direction and keyphasor/tacho position as well as position of the particular proximity probe.

 

What equipment is needed to perform orbit analysis?

A typical configuration would consist of a pair of proximity probes and a keyphasor(tacho) per one bearing. Dewesoft supports virtually unlimited number of bearings, so this configuration can be multiplied as many times needed in a particular application. If needed, Dewesoft Orbit Analysis supports also mono configuration with a single probe per bearing and offers additional customizability options to suit different measurement needs.

 

How about in terms of Dewesoft HW? What DAQ system do you recommend for the job?

The decision about the best DAQ is dependent on a few factors such as: the type and model of the eddy-current probe that is going to be used, the number of channels required for the measurements and if there might be additional parameters to monitor besides the displacement from the probes. The first thing to consider is the needed range for the particular proximity probe and the type of connector used. For most cases an LV amplifier is the right one for the job as it covers the needed range and is also able to provide excitation to the probe itself.  Should you require assistance with this decision, our local representatives would be happy to help.

 

Do you support any industry typical orbit analysis displays?

Sure we do. There is a predefined OA display to help you out in the beginning and there are virtually unlimited options when it comes to defining your measurement screen. In short we support: raw/direct orbit(with clearance circle), averaged orbit(with clearance circle), filtered/nX orbit, shaft centerline(with clearance circle), full motion graph, bode plot as well as order and FFT waterfalls vs. RPM.

 

Channels are easily added to different dedicated displays(Orbit plot, polar plot, 2D graph) in order to create exactly what you need. For example, the shaft centerline with clearance circle is easily transformed into a full motion graph with a single click.

 

Is Dewesoft Orbit analysis capable of compensating for any shaft shape irregularities?

Of course. This is done through dedicated Runout compensation, which can be performed at any desired rotation speed - user inputs the speed and selects the number of revolutions to average when performing the runout compensation. The compensation itself is handled through a dedicated measurement screen and is completely automated once started.

 

I have placed my proximity probes on the machine and connected them to Dewesoft. Now each probe shows a different value as their distances to the rotor are not exactly the same. Is there any way I can solve this in the Orbit analysis software?

This is easily solvable through DC Gap measurement and offset correction in the channel setup of orbit analysis. If you are not sure how to perform this, press F1 for an online manual when in channel setup of Orbit analysis module.

 

I have already performed a DC gap correction and want to also do a runout compensation before I start acquiring my measurement data. Is the runout compensation going to be confused by the previous DC gap correction?

No, they are entirely independent of one another so you can easily use both functionalities. The runout compensation ‘‘knows’’ not to take the DC gap into account.

 

I have made a measurement and stored it, but realized that the analysis parameters were not set entirely correct. Can I fix this in post-analysis?

You can and it is also rather straightforward to do. Dewesoft OA stores the time domain data by default, meaning you can always recalculate the results in Analyse mode. Simply open the recorded data file and edit the desired settings in channel setup for Orbit analysis. Press recalculate ant that's it! Not sure how to do this? Reach out to one of our knowledgeable support engineers at support@dewesoft.com or contact a local representative.

 

Are you going to charge fees for future updates and upgrades to the Orbit analysis module?

Absolutely not. Since this is Dewesoft, the same is true as with any other module in our product line: no license renewal fees, free updates and lifetime support included.

 

Do you offer any monitoring capabilities together with Orbit analysis measurements?

We do, together with our Historian database we can offer a complete solution for long term condition  monitoring. Since these systems can vary in their architecture and requirements, we recommend getting in touch with the local representative and they will arrange for our engineer to contact you and prepare a solution for your measurement needs.