Tagged With "1x"

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1X AC line frequency excitation in Motor

The Maniac ·
A centrifugal fan 168 kW, 1480 RPM Overhung with Flexible pin bush coupling was running normal with vibration max 3 mm/s since 4 years. There was a sudden increase in vibration at 2x RPM frequency up to 8 mm/s inin coupled condition at motor NDE side Horizontal and fan NDE vibration observed max 3.6 mm/s with minor looseness symptoms . Motor Solo run was taken and observed with 1x Line frequency(49.97 Hz) observed dominant in spectrum with vibration observed up to 3.4 mm/s in motor NDE...
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1X at Hydraulic Coupling

Nera ·
Dear all, We're facing a problem with the Hydraulic Coupling of boiler feeder pump. The absolute vibration taken by CSI2140 is very high at all directions, at the moment, it's more than 10 mm/s. This has happened for a long time and can't find the answer. - Input:1500 rpm; Output: 5971 rpm Only 1X of output shaft dominates. The spectrum is below: But the relative vibration of this shaft (taken by online system) is very small, about 20 um. If you have any ideal, please help me, all opinions...
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1x component in conveyors

subh ·
We have a new green field Project. Numbers of conveyor are installed. In aprrox 95 % of conveyor i m geting only n only 1x component.all these conveyor are on steel structure. The vib is normally 15 to 20 mm/s. What is the possible cause of it.
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1X motor on belt driven Agitator

Jack1954 ·
If you have an Agitator 100 hp motor belt driving a Agitator motor 1800 rpm and Agitator 335 rpm. Typical Blend Chest Agitator. Suddenly on a survey the motor inboard 1X jumps from very little to .4 ips vertical, .1 axial and .1 Horiz. I think the most likely reason is looseness in the motor shaft caused by the bearing or housing looseness. Very unlikely after so long the motor pulley just jumped out of balance. Yeah it could have slung a weight. Anyone had this before? I am asking to remove...
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1X up to 7X vibration observed

Hesam267 ·
Hi everybody i observed high speed compressor (42000 rpm) with high 7x (1x,2x,...,7x). machine semiopen impeller has 7 main blade too. this is my question: is it any relation? and what can rise all x? P.S - all bearing clearance found OK.
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Dominant 1x and 2x at FDEH (simply supported type)

Rahul v dan ·
Hello members, We have a vibration problem of an ID fan of 75 KW motor driven. Spectrum having dominant 1x rpm initially with overall vibration 6.0 mm/s and also phase shift of 65 degrees between H and V at FDE. From past week there is sudden increase in 2x which is as much as 1x rpm in the FDEH spectra. Alignment readings are found ok and so phase. Plummer block bolts were also tight and good.Can the prevailing unbalance can cause an increase in 2x rpm? What are your thoughts?
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Re: 1x component in conveyors

Walt Strong ·
Eccentricity of the rolls. Walt
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Re: 1x component in conveyors

subh ·
Thanks Walt I dont understand of which component ecentricity u were talking... please explain me.. I have solve The 80 % of this problem by structural strengthening and fluid coupling balancing.. But than also m not satisfied
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Re: 1x component in conveyors

Walt Strong ·
You provided no details to your problem, so I was just guessing a possible cause of the vibrations at 1X shaft speed. Is the vibration you are concerned about at motor shaft speed, fluid drive output speed, conveyor drive speed, or some other shaft speed? Even a psychiatrist solves problems by asking questions! Walt
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Re: 1x component in conveyors

RAAL ·
Hi I recommend reviewing structural issues, this may include performing designs including structural analysis. regards
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Re: High 1X motor vibration and baseplate stiffness

Ron Brook ·
If you still have vibration without power to the motor, then something running near this motor is causing that vibration. For a motor to change vibration over time, several things are possible: The motor base may have settling issues causing a rigid body mode to move closer to running speed. The motor could have thermal issues causing rotor bow. If there is vibration close by, check that out first
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Re: High 1X motor vibration and baseplate stiffness

white walker ·
settling issues causing a rigid body mode to move closer to running speed.what does it mean?@ron brook
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Re: High 1X motor vibration and baseplate stiffness

rgf12 ·
Generally speaking the box channels used like this are quite stiff as long as the underlying base is solid ( no grout issues or cracked welds). I would do a bump test on the base in 2 directions to see what the natural frequency is and isf it is close to the running speed of the motor. If that isn't the driver then you can move on to other possible causes. What does the pump vibration data look like? What type of coupling?
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Re: High 1X motor vibration and baseplate stiffness

Walt Strong ·
Vibration looks higher after shaft alignment. Looks like a lot more shims under one end (NDE?). Are you really sure that alignment is good? Walt
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Re: High 1X motor vibration and baseplate stiffness

Ron Brook ·
Walt, The height of the shims looks OK but they don't cover the entire foot of the motor. That can cause a stiffness issue. Of course, a bad alignment will also cause higher vibration.
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Re: High 1X motor vibration and baseplate stiffness

Unplugged.Charles ·
Yes, motor NDE foot was not supported with wider shims. I agree with you Mr.Brook. to RGF12 Pump vibration is maximum 1.0 mm/sec RMS. It's very stable. And coupling is flexible disc type. to all At first, we added beams for increasing horizontal stiffness as like pictures. And motor - pump was re-aligned by laser tool again. Vibration amplitude was reduced. Now it shows about 5mm/sec RMS. But motor still has strong 1X vibration. And motor terminal box, cable, paved floor and the others still...
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Re: High 1X motor vibration and baseplate stiffness

Ron Brook ·
If you have a beat frequency, that is proof that there is something else running near the same speed that is added and subtracting to the vibration at 1x. Check all equipment neat this motor. Have you checked the alignment yet? Have you soloed the motor?
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Re: 1X up to 7X vibration observed

John from PA ·
How is this measured (casing, proximity probes)? What is the overall or direct amplitude? Can you post some plots?
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Re: 1X up to 7X vibration observed

Hesam267 ·
no Unfortunately i dont access now . but maybe i will bring it.
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Re: what happens if 6226 bearing is used instead of 7226 on a vertical pump motor

John from PA ·
Have you done a bearing to bearing comparison? The 6226 is a deep groove and the 7226 is an angular contact so axial capability may be significantly different as will be the basic load ratings. The links below will take you to the appropriate SKF sites. Along the left edge of the screen and near the top is a means of doing calculations on exactly what you may have. Click on "Calculation". 6226-Z http://www.skf.com/group/produ...l?designation=6226-Z 7226 BCBM ...
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Re: what happens if 6226 bearing is used instead of 7226 on a vertical pump motor

Onderarslan ·
John, thank you for your comments. I wonder the reason of dominant 1X on both radial and axial sides. And when we couple vibration amplitudes rise by keeping dominant frequency same as uncoupled.
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Re: what happens if 6226 bearing is used instead of 7226 on a vertical pump motor

Onderarslan ·
The only difference between two bearings seems shaft fits but axial and radial clearances may be different. Shaft fits 6226 7226 -0,36mm -0,12mm Housing fits 6226 7226 +0,03mm +0,03mm
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Re: what happens if 6226 bearing is used instead of 7226 on a vertical pump motor

ivibr8 ·
Quote: "Sister another motor has vibration less than 1.0mm/s and I learnt that the customer is using 6226 bearing instead of original 7226 type bearing. I suspected overhung rotor issue or probable resonance due to structural looseness on somewhere" To be honest, I am not sure I follow the logic. Just because one motor is using a 6226 vs. 7226 bearing is not leading me to believe a overhung rotor issue or probably resonance due to looseness on " somewhere " is your root-cause problem. John...
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Re: what happens if 6226 bearing is used instead of 7226 on a vertical pump motor

Onderarslan ·
Hello JP, Thank you so much for your comments. One year ago the customer had high vibration on the motor and then a service company advised customer to change NDE side 2x7226 bearing with 2x6226 bearing and after that vibration disappeared until last week. Our site experts did some site survey and we noticed that NDE side bearing shield is too large (70-80 micron house fitting) we plan to repair during bearing replacement. Please see enclosed coupled and uncoupled vibration measurements.
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Re: what happens if 6226 bearing is used instead of 7226 on a vertical pump motor

ivibr8 ·
One thing of interest: The data shows significant changes in 1X ON THE SAME DAY! If the problem is simple unbalance, I would not expect such a large variance. Are both pumps on a common discharge line? Is there a possible beating phenomena going on? Having a bolt not engaging is not good. Is it the root cause issue? I don't know.
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Re: what happens if 6226 bearing is used instead of 7226 on a vertical pump motor

Onderarslan ·
Significant change due to disconnection of the coupling from the pump. That's why 1X is different in the same day. I wanted to outline that vibration of the motor is around 3 times more than another sister motor even uncoupled position We will change the bearings, check rotor unbalance and shaft bent issue. I will share final vibrations after operation we will do. Regards
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Re: what happens if 6226 bearing is used instead of 7226 on a vertical pump motor

Onderarslan ·
Dear all, I wanted to inform about final stage of the case. After several trials we noticed that vibration amplitude drops significantly when we add a few shims to bottom side of frame and tighten the bolts. Now the vibration is around 1.2mm/s again 1X is dominant.
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Re: High 1X motor vibration and baseplate stiffness

Jim Thomas ·
With the equipment running: 1. Loosen motor hold down bolts 1 at a time and record amplitude and phase change
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Re: 1X AC line frequency excitation in Motor

Rotating Guy ·
Hi, Could you please send more details like FFT, TWF on what your are telling on your post. regards,
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Re: 1X AC line frequency excitation in Motor

The Maniac ·
Pls find the attachment for spectrum and wave form attached
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Re: Dominant 1x and 2x at FDEH (simply supported type)

William_C._Foiles ·
Look for something in addition to imbalance to cause an increase (change) in 2X - You do not say that 1X increased. Did 1X change, increase or not? What is F as in FDE?
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Re: Dominant 1x and 2x at FDEH (simply supported type)

John from PA ·
What type of coupling is being used?
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Re: Dominant 1x and 2x at FDEH (simply supported type)

Walt Strong ·
I assume FDE is Fan Drive-End bearing. This bearing often has thrust bearing and radial bearing. To OP, what type of fan bearings? Walt
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Re: Dominant 1x and 2x at FDEH (simply supported type)

Rahul v dan ·
WILLIAM SIR, 1x component is same at Fan Drive End.
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Re: Dominant 1x and 2x at FDEH (simply supported type)

Rahul v dan ·
Hello sir, Coupling used is grid coupling ( coupling changed recently)and fan bearings are radial bearings.
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Re: Dominant 1x and 2x at FDEH (simply supported type)

Kishore kumar ·
Could you please Fan Vibration spectrum before and after changes .
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Re: Dominant 1x and 2x at FDEH (simply supported type)

Rahul v dan ·
Hello sir, please look in to photo
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Re: Dominant 1x and 2x at FDEH (simply supported type)

Kishore kumar ·
Tight all Nut - Bolts of structure ,equipment and coupling and check if there is any cracks developed .Do balancing , Vibrations might come down .
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Re: Dominant 1x and 2x at FDEH (simply supported type)

Rahul v dan ·
Hello sir, planning for the same
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Re: Dominant 1x and 2x at FDEH (simply supported type)

Rohit02 ·
It can be a case of rotational looseness. Bearing could be loose in plummer block. Kindly also check for interference/clearance between bearing OD and plummer block ID. Unbalance sometimes cause this clearance to increase by periodical impacting.
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Re: Dominant 1x and 2x at FDEH (simply supported type)

hkilic ·
Seems like loosenes.
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Re: HIGH VIBRATION IN CENTRIFUGAL COMPRESSOR (RUNOUT)

William_C._Foiles ·
I tried to polish the shaft but I did not I managed to remove completely, the slow roll vector of the XT-530-A and XT-530-B sensors is 1.2 mils, the strange thing is that when it comes to compensate the bode plot of the XT-530- B the slow roll vector is added to the vector of 1X, the question is: This is a very long (part of a ) sentence, which is hard to follow. What does int mean that you 'tried to polish the shaft?' What was the action you considered to be polishing? The fact that the...
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Re: HIGH VIBRATION IN CENTRIFUGAL COMPRESSOR (RUNOUT)

John from PA ·
At least one company infers that simple subtraction of runout is a viable procedure. As Bill has pointed out, they are totally wrong. Quoting from Monitoring strategy – Runout compensation "Obviously degaussing, sleeving, machining and/or polishing the shaft surface can minimize the causes of runout, but it is time consuming and not always physically possible or practical. In such a situation it is more cost effective to simply subtract the recorded slow roll runout from the actual...
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Re: HIGH VIBRATION IN CENTRIFUGAL COMPRESSOR (RUNOUT)

Walt Strong ·
Is the OP data plots from a Bently system or a B&K system? Compensation of Slow Roll 1xSS mechanical and/or electrical runout is by Vector Subtraction, correct? The Compensated 1xSS can be lower or higher than the Uncompensated values depended upon each vectors amplitude and phase, correct? Walt
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Re: HIGH VIBRATION IN CENTRIFUGAL COMPRESSOR (RUNOUT)

John from PA ·
Re: HIGH VIBRATION IN CENTRIFUGAL COMPRESSOR (RUNOUT)
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Re: HIGH VIBRATION IN CENTRIFUGAL COMPRESSOR (RUNOUT)

Shurafa ·
Shall the compensation always result in an amplitude reduction? Yes. Can the compensation result in an amplitude increase? Yes. The reason for answering yes for both questions without facing a contradiction is that both are true but at different points. The analyst needs to remember that applying compensation requires two points (two vectors). One is fixed while the second is variable. SR is Slow Roll vector which is fixed. If the compensation is applied on the the same speed of the SR (400...
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Re: HIGH VIBRATION IN CENTRIFUGAL COMPRESSOR (RUNOUT)

William_C._Foiles ·
Bently used to like a second mode compensation to 'correct' the Bode plots. This is interesting when applied for diagnostics, but using polar plots overcomes this issue anyway. 1X compensation (or any Nx compensation) will reduce the 1X component (Nx). The old DVF 2s (and 1s for those who used them) would subtract the 1X as a digitized signal; so, that you could look at orbits. Test question: Would removing the 1X from a signal reduce the p-p level in all cases? (or not increase - assuming...
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Re: HIGH VIBRATION IN CENTRIFUGAL COMPRESSOR (RUNOUT)

carlos msr ·
Hi William Previously, the compressor had a high vibration shot just started the turn, the runout was excessive (rust, porosity and scratches), the shaft was polished and the runout was minimized, As mentioned by John it is very difficult to machine the shaft for time and we depend on the compressor. This compressor was previously repaired and stored for a year, however, we had no history of its behavior.
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Re: HIGH VIBRATION IN CENTRIFUGAL COMPRESSOR (RUNOUT)

carlos msr ·
Hi Jonh is correct we can not spend more time in the compressor since we are out of the program. Based on your experience, would you recommend modifying the set poin of shutdown for high vibration or do you think it could affect at some future time? Currently the set point of the XT-530-B sensor was modified from 4 to 5 mils, only 1 mils was increased. If you have any other recommendation I would appreciate it.
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Re: HIGH VIBRATION IN CENTRIFUGAL COMPRESSOR (RUNOUT)

John from PA ·
Since you can't fix the journal properly, and have already elected to raise the set-point, there is little that can be done except to make sure the machine is trended, and inform everyone that a decrease in indicate amplitude is just as important as a increase.
 
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