The highest peak observed on a large 6-pole motor running a direct drive axial fan in cleanroom service is .122 at exactly 3600 cpm/60 Hz. The motor rotational rate is 1195 rpm. The data was collected when the motor was being driven by a VFD, operating at full speed, (60 Hz.) When the motor is...
I am an idiot...I must have been totally brain dead when I wrote in! The vibration is at 60 Hz! That is half the frequency of the usual electrical frequency vibration I see, (120 Hz/ 2 X Line freq.) The VFD was operating at 60 Hz. Sorry for the initial misinformation.
Regards,
Tim
I recently encountered a large 6-pole induction motor driving a vaneaxial fan in cleanroom service. The motor was tested at full speed/60 hz through the VFD. The highest spectral feature was a .112 ips peak exactly at 30 Hz. (I had sufficient resolution to determine that this was not 3 X M. When...
I have recently been seeing a number of Browning "B5V" sheaves used in air handler applications. The claim is made by the manufacturer that these are usable with both standard and narrow belt profiles. It would seem that it must be a compromise, fitting neither well, and in addition, it is...
1. I would STRONGLY recommend against any absolute severity classification based on temperature. Small temperature differences may be extremely meaningful, depending on load/emmissivity, etc. Also, in many cases, you reaslly don't know the real temperatures, which may be far different from...
Is it possible that the 2 X increase is actually at 2 X Line feq. (120 Hz)> If you don't have enough spectral resolution, it can be hard to distinguish on a 2-pole motor. Increased 120 Hz vibration is related to a motor electrical problem of some sort. I have seen a poor electrical connection on...
It refers to a pattern that sometimes looks like a "school of angel-fish" seen in the time waveform when an impact rapidly rings down with very little dampening. It's often associated with the metal-to-metal contact that occurs with damaged rolling element bearings.
Tim
Does anyone have experience with using vibration analysis on the drive mechanisms of tracking antenna systems? Is it effective in detecting common failure modes? (Not concerned with structural vibration, modal studies, etc.)
Thanks for any input!
Belt manufacturers (such as Gates) can give you a series of inexpensive plastic templates which quickly let you determine whether excessive wear is present. I have seen them for all of the standard sizes and belt profiles.
