Machinery Vibration Spectrum Order Plot
For machinery vibration analysis, please explain how to continuously display a FFT preview / 2D plot with vibration amplitude (peak to peak) on the Y-Axis and orders of running speed on the X-axis?
I was able to generate the desired graph (see below) as a cut of a 3D waterfall plot however I'd like the plot to continuously display data (similar to FFT preview). The cut below only displays data associated with a run-up or a coast-down.
If this needs to be part of a future upgrade, my ideal implementation would be to have a drop down in the FFT preview widget options to select X-axis units (Hz, orders, CPM) and a dropdown to specify the frequency / speed channel. I have both the Orbit Analysis and Order Tracking licenses.
Also another enhancement to the FFT preview and 2D graph: Please add a text field to automatically display the selected "Amplitude display" on the plot. This is important for reporting. In the screenshot below, the selected Amplitude display is "Peak-Peak" so ideally "Peak-Peak" would appear next to the units on the Y-axis label. Also, the "RMS" button currently in the top right is misleading....I recommend moving or renaming it.... a user may assume that the displayed amplitude is RMS.
Dear Matt,
thank you for reaching out to us.
I believe the functionality you are looking for can be achieved by using the Order waterfall vs. time function:
The channel, acc/Order waterfall [time] can then be assigned to a 2D graph:
Please let me know if this this is what you were looking for.
Best regards,
Pika
Thanks Pika. I tried using the Order waterfall vs. time feature in OT with a 2D graph. I'm using proximity probes which have a large DC offset so the plot has a large peak at 0 orders. I couldn't find an option for DC cutoff in OT.
In Orbit Analysis, I enabled the Two sided Order waterfall vs. time and enabled the DC cutoffs and was able to plot it to a 2D graph. See screenshot below. The plot appears to be correct however the graph needs to be associated with either a runup or coastdown. I'd like the plot to work all the time, regardless of whether or not the OA direction channel is set to Runup, Coastdown, or Steady state.
Dear Matt,
you are correct- we currently do not have DC removal in OT. In this case, you would first have to use a high-pass filter on the input signal, either via the Hardware under the analog input setup, or in Software with a FIR/IIR math filter. In your case, the cut-off frequency would probably be around 10 Hz.
If you'd like to plot the data independent of the speed state, please disable the check box for Separate spectra for runup/steady state/coastdown:
Best regards,
Pika