We are analyzing some 24,000 - 30,000 rpm motorized spindles equipped with ceramic bearings that are classed at ABEC9. I don't have specific bearing numbers, don't know the DN#, or the specific type of lube being used (yet).
The vibration data for the first few units we have looked at has what...
We are analyzing some 24,000 - 30,000 rpm motorized spindles equipped with ceramic bearings that are classed at ABEC9. I don't have specific bearing numbers, don't know the DN#, or the specific type of lube being used (yet).
The vibration data for the first few units we have looked at has what...
I'm looking for any feedback from users of capacitive proximity probes (e.g. Vibrosystm 'PCS' models) regarding their claimed insensitivity to electrical runout & surface magnetism variations. Has anyone done any direct comparisons of eddy current (Bently) vs. capacitive transducers to determine...
For measuring trees, there is no difference in accuracy. Think of it this way - 1 arc-sec = the width of a dime viewed from 1.25 MILES away. So even with 10 arc-sec, you're looking at something the width of 10 dimes, about 5 inches, from 1.25 MILES. So across an acre, you'd be down do the 1/2...
Twitchy,
I've got 20+ years experience analyzing rotor dynamics in sleeve bearings, and have studied shaft centerline movement extensively on large motors and turbomachinery.
For a motor in the 2,250 hp range (as TPL pointed out) a clearance of 1.5 mils per inch of shaft diameter will work...
Thanks Tom. The original rotor is being used, made circa 1950 (not real sure on this). I do not know if air gap was changed, that is an excellent question and one I took for granted. The stator is definitely more rigid as we went from 4-segment to continous stack. There are not any air gap...
I got the article, thanks. Didn't get too much out of it.
We are looking at re-tuning the core by linking mechanically to the frame, but IMHO it is way too trial and error. I doubt if anyone will be able to model and predict the effects.
The rewind contractor is standing firm that the...
360 slots, 56 poles hydro-generator, and yeah it's big, about 23.5 FEET in diameter.
There is indeed a fractional slot winding (6 3/7 I believe).
We feel it is likely electromagnetic as well, and inherent in the design. But we've got a high noise (95 dB) situation, and a customer unwilling to...
Thanks electricpete. The 'keybar' is a piece of square steel tubing, ~ 2" x 2", than runs vertically along the outside of the back of the core iron. It is welded to the stator frame and, for lack of a better description, abuts the core iron. Relative tightness between the core and the keybars is...
Thanks Walt.
I've been suspicious of looseness based upon the 120 Hz harmonics, but the group seems to feel that with the brand new re-stacked core that things are 'tight'. One area that is in question is the fit between the keybars (vertically mounted between the stator frame and core iron...
Thanks Edison.
Regarding loose laminations, this is brand new re-stack of the core, and I've heard the stator core bolt tensions reviewed in our conference calls, and they did not raise any flags amongst the group. However....no one that I know of did a knife test.
Regarding keys, we had taken...
I've got a unique situation with a recently re-stacked hydrogenerator. Vitals are:
# poles = 56 ; # stator slots = 360 ; line freq = 60 Hz ; rpm = 128.57
Old design had 4 stator core splits ; New design uses a continuous core stack
Vibration taken directly from the back of the...
