Greeting to all the Vibration Gents,
I recently got a set of data from a Motor which drive a screw compressor. The dominant peak in radial (both horizontal and vertical) of the NDE and DE is 1xRPM, the dominant peak in axial direction of DE is 2xRPM (there is no data for axial of NDE, might be because of the cooling fan). Things is when I'm working with the phase data, some data point toward unbalance, but some to misalignment as in the pic below:
1. For unbalance symptoms the data shows:
- Dominant 1X RPM
- Horizontal phase difference closely matches the vertical phase difference (V1V2 ~ H1H2).
But one thing is that the radial phase differences (V1H1, V2H2) are not close to 90 deg. Is that if unbalance occured, the radial phase difference should close to 90 deg or there will be case that even if the unbalance exits the radial phase difference can be in phase.
2. For Misalignment symptom the data shows:
- Dominant 1xRPM in radial (should 2xRPM must be also present?)
- Dominant 2xRPM in axial Motor DE
- Vertical phase difference across coupling is 133 deg
- Radial phase differences (V1H1, V2H2) are close to 0 deg
But one thing is that the horizontal phase difference closely matches the vertical phase difference. Is that if misalignment occurred, the horizontal phase difference and the vertical phase difference should not be consistent (for example if H1H2 = 0 deg, the V1V2 can be expected to show 180 deg). Or there will be case when misalignment occurred, the horizontal phase difference can be close to vertical phase difference.
Could we do a discussion on this matter? I am really exciting to be enlighten by your experiences. I've also attached the spectrum and motor datasheet for your reference.
P/S: This case is not in my company, just a case I've been share with, so I will have very limited information. So sorry for that.