Basic machine setups are typically made to collect all the data we need for each asset. This is not always possible or reasonable as we would spend far more time collecting a massive amount of rarely used data. So, we compromise by creating additional readings on the fly to get the best of both worlds. This blog is to help familiarize vibration analysts with this concept, and hopefully, you will find better success and confidence when making calls for repairs in the future.
When to Collect Additional Data
Rotor bar pass frequencies show on the spectrum as running speed harmonics with sidebanding at the number of poles x slip frequency. A standard 1800 RPM motor has 4 poles. If we strobe the motor and find the actual speed is 1794, then the slip frequency is 6. Therefore, we take 6×4, which equals 24 – now, depending on our initial setup, we may or may not have the resolution to separate such a small delta on these sidebands. When performing analysis in the office, the running speed harmonics may look like there is looseness in the motor bearings or on the shaft rather than allowing us to identify the actual problem, which is a cracked or broken rotor bar in this example. Had we collected high-resolution, low-bandwidth data in the field, it would have been easy to avoid such a pitfall, and we would have been more accurate in our analysis.
There are other instances where you would want additional data above and beyond the rotor bar pass, and as you progress in your skills as an analyst, collecting additional data will become second nature as you dig deeper and deeper into more complex issues.
Another common instance where you may want to collect additional data would be on a machine that you don’t collect data on or isn’t in the database at all. However, you noticed it was running a bit rough and wanted to take a quick look at what was wrong with it.
The 3 Methods of Collecting Additional Data
- Copy and paste a similar machine already loaded in the Acoem Falcon into off-route.
- Create an entirely new machine with a standard set of readings.
- Create specific readings to apply to a small group of points.
1. Copy and Paste
This is the easiest method of collecting additional data, especially if you already have a similar machine loaded to your collector. Copy the machine, choose the off-route button on the screen, and paste. This will create a new blank machine you can rename and use to collect another set of readings. You will only acquire the same data that you would always obtain, so it’s not incredibly useful for further analysis on a specific machine unless you were to make some kind of process change, such as adjusting the load or perhaps uncoupling the motor and getting an additional set of readings on just the motor to compare. Either way, this is simple and quick; it will prove helpful if used appropriately.
2. Creating a New Machine with Standard Readings
If you do not already have a similar machine in your Falcon, you can create a new one in the “Analyze” module of the Falcon. This will allow you to choose the number of points or “groups,” provide a name, and allow for uploading to NEST i4.0 for further analysis on the machine. There are several settings in the Falcon when doing this with the built-in templates, and you can always add additional readings if you want more data. This is not the best method for collecting additional data on a unit where you have already collected the base set of readings because you will get more data than you already have.
3. Create Specific Readings to Apply to a Small Number of Points
The final recommended way to collect additional readings for further analysis is by using the Falcon Vibration Analyzer to create these readings individually. To do this, you need to create a new machine with the standard template, this will create an asset with two readings, which you can modify or delete as needed. Once the machine is created, you can add a template reading setup from the drop-down menus and modify it to whatever you need, such as higher resolution or increased bandwidth. The options are endless here, I recommend you practice this function and familiarize yourself with it.
By using these methods and collecting additional data as needed to analyze potential issues in the field, you will find it easier to make recommendations for repair and have to make rechecks less often.
