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Asset Condition ManagementPosts About vibration/alignment/balance
Fan 2X Vibration
RM Registered Member
Registered Member Hi Dave, Appreciate the feedback on the weekend. You've given me lots of new ideas to troubleshoot! Responses to your comments and questions below as well as some photos and dwgs for clarification. ...please provide photos of how the fan is connected to concrete. How is it isolated? The attached jpg shows two out of the four vertical spring isolators (at south-east and south-west positions) as well as a horizontal spring. There are 2 more vertical springs on the opposite corners (north-east... [ more ]
Registered Member Now we are getting somewhere....please provide photos of how the fan is connected to concrete. How is it isolated? I see flexible boot in you new images. The "middle" image you recently posted shows "rust", brown colored powder where the fan meets the concrete. This is where the movement is happening. I do not seen any bolts holding the fan bearing support structure? If you are using a prox probe, you need to be aware of where you are trying to detect movement. If you put the probe on the... [ more ]
Registered Member Thanks for the feedback, Dave! Much appreciated. I had many of the same thoughts so we're on the same page for sure. I'll add some detail below related to your comments. ********************************* - I suspect the shaft is flexing at full speed - I was wondering whether the shaft or pillow block was shifting position causing the dynamic misalignment symptom, so installed prox probes to monitor DC gap voltage at full speed and during coast down. Vdc gaps didn't change much at all... [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
about ACC adapter for CSI 2130
RM Registered Member
Registered Member thanks Gearmesh10 I know why , the problem is from my setting . initially , i plugged 628A adapter then choose Mux is "OFF" ( Because i think Mux dedicate to A 648 adapter not 628 A) and that is why value on channel A and B have same value. Finally, i set Mux " ON" the problem is close when each channel has acquire right data. thanks. [ more ]
Registered Member The MUX will work better for the 2130. I used it may times. It also helps to color code the cables for each channel. Easier reference. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Abnormal high vibration readings in a 3000 RPM centrifugal fan
RM Registered Member
Registered Member My bad, it's 30k CPM... 500Hz.... 10x? Any side bands? [ more ]
Registered Member I've seen something similar, There's a reduction in the amplitude... Well the folded paper acts as a mechanical "filter" for high frequency (in this case is not good enough try more folds or a credit card, to measure the low frequency content) but this result is pointing to high frequency overloading the sensor well this still bad news on your bearings, in your last FFT there's a lot of activity around 30kHz what's that? as a learning exercise try to measure the acceleration waveform at... [ more ]
Registered Member I am very grateful for the help and suggestion received so far. I have attached a screenshot with different readings as suggested. With a folded paper in between sensor and bearing housing and Fmax value set to 240000 CPM, the overall vibrations reading shown is 3.18 mm/s. The transducer is of 100 mV/g sensitivity. My understanding based on above comments, is that this is a sensor overload/saturation issue and it would be ok to run the fan under current conditions. Please correct if I am wrong. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Generator sleeve bearing shaft vibration probes X&Y are showing different values.
RM Registered Member
Registered Member Your cursor is shown at 25 Hz (1250 cpm). Was the generator synched at the time? Can you expand the region from 0 Hz to about 100 Hz so we can get better definition of the frequencies that are shown? I'm interested in knowing if that DE is showing 1X and 2X and the NDE only showing 1X. Also, what type of coupling is at the DE of the generator? [ more ]
Registered Member Dear Mr. John, I understand the difficulty now, I better be posted in .pdf format. Anyways an experience in this forum. Please find the attached pdf file. [ more ]
Registered Member As you can see from the image I've attached I can't make out the two lowest spectra from your original post. This isn't your problem, just one I encounter on this particular forum where the original post overlaps the forum header information. Can you post the data as an Adobe attachment? I would specifically be interested in knowing whether the data showing the 2X is the DE or NDE of the generator and also if the generator has a coupled exciter. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Balancing shop floor operating and testing speed
RM Registered Member
Registered Member For a low speed balance, i.e., a rotor with rigid behavior, I do not understand high speed variation. The rotor is balanced as a rigid body. High speed (if meaning similar to that in ISO 1925 for high speed balancing) does not apply. [ more ]
Registered Member Then low speed balancing and high speed variation ? [ more ]
Registered Member As I read, your customer asked you to verify the balance measurement at speed. This would not be technically proper. One of the old ISO 1940 (as I recall) had some comments regarding this. Measuring at speed (often) will not produce a valid measure of a low speed balance, particularly insitu if this were to be the case. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Difference in Vibration Standards ISO2372 and ISO10816
RM Registered Member
Registered Member stringent requirements will benefit in longer run to keep machines running at lower levels of vibrations and hence increase reliability. This is not necessarily sound logic. ISO standards do (attempt to) set severity levels that permit operation without deterioration from vibration. Setting lower limit values than that will not add much if any value. Your plant reliability data would be an excellent guide in this area. There are some 20816 standards out if they pertain to your equipment. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Rotor Bar Pass Frequency Issue
RM Registered Member
Registered Member I see quite a support stand for that motor. Usually those are fabricated by welding. I’ve often found them to not be properly stress relieved prior to machining the upper and lower flanges for concentricity and squareness. Unfortunately these dimensions aren’t easy to check in the field but if the stand is ever removed, it might be worthwhile to have the stand checked in a boring mill. [ more ]
Registered Member Sorry forgot to attached image. [ more ]
Registered Member Thanks for the reply John, there might be some soft foot, from the velocity spectrum there are peaks <1 mm/sec and harmonics that indicates looseness and misalignment but I'm not sure if this can distort the motor frame enough since the motor sets on top of the pump frame. The 6x RPM from the spectrum I think is the 2x LF which is around 6000 CPM (airgap?) because this motor have 6 poles. I am from the Southern Hemisphere, so our line frequency is 50 Hz (3000 CPM). [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
𝐑𝐞𝐜𝐨𝐠𝐧𝐢𝐳𝐢𝐧𝐠 𝐕𝐢𝐛𝐫𝐚𝐭𝐢𝐨𝐧 𝐏𝐥𝐨𝐭𝐬 (Cat II Question)
RM Registered Member
Registered Member 3-d representations and color coding amplitude have not made their way to some instrument manufacturers that have a big market influence. [ more ]
Registered Member Talking about 2 dimensional plot (amplitude vs frequency) to 3 dimensinal (time or speed) I wonder why spectrograms are not popular in vibration? [ more ]
Registered Member Waterfalls are the same as cascades in other places. A waterfall like Bently does is a 2-dimensional plot of 3-dimensional data. Matlab (Trade mark) and Python will plot 3-d versions for spectra or other. For spectra the axis are frequency, amplitude, and parameter. Parameter could be time, speed, pressure, whatever. This type of plot can be helpful in understanding how data changes vs. a parameter. Data for vibration is usually spectra. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Reducing Electrical Runout
RM Registered Member
Registered Member Just additional info. Methods for reducing electrical runout such as collars, galvanization, micro coating, etc. they are very demanding on time-consuming and additional cost. Risks can be in influencing the mechanical properties of the shaft, concentricity, peeling, ... An alternative to these methods are previously described methods local disruption of the surface burnished measuring track. They are indicated in the document under the name micro peening. These methods take an hour to... [ more ]
Registered Member Another worthwhile paper on this topic can be found at Predicting Shaft Proximity Probe Track Runout in motors and generators . [ more ]
Registered Member One of my specializations is the final preparation of rotary components when standard procedures do not help. Part of our products are high-speed machines or machines according to API standards. I was in charge of the implementation of runout measurement (methodology, V-Blocks, etc.). But the situation forced me to learn to repair mechanical and electrical runout as well. If you find out that you are outside the limit of total runout on a finally ground component worth $100,000, it is not... [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Vibration Analysis Cat II Sample Question
RM Registered Member
Registered Member Interesting discusion. Thanks a lot for the comments. I'm attaching a waveform with a phase measurement from CSI literature. How common is this format among vibration practitioners including CSI users? I really don't know. In my small world, it is not that common. Now common or uncommon becomes a result of everybody's experience. (By the way, I'm a CSI user.) With respect to the exam and its affiliation with vendor-specific conventions, the standard, I guess, avoids mentioning/referring to... [ more ]
Registered Member I am not at all saying every Cat II candidate needs to be familiar with BN or the trademarked word Keyphasor. But the term, or “once-per-turn” marker is quite common in the industry (it appears in various API specifications) and depending on the connected instrument, if you make use of the Keyphasor or once-per-turn output of a rack, your instrument may or may not display some form of marker in the waveform. [ more ]
Registered Member So, you are saying every Cat II candidate should have experience with Bently? I can tell you from my experience, even if there is Bently Nevada hardware installed, you can connect the other system on it and I have never seen any dots as a tacho signal. So, for this case, candidate should be brought in front of the Bently display to know what those dots are? Is this a Bently Nevada exam? [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Slow roll compensation
RM Registered Member
Registered Member There isn't any way to predict "amplitude of vibration", assuming by that terminology you mean what might appear on a monitor. As an example, lets say that 0.00034 inches electrical and mechanical runout (E & M) is simply uniform eccentricity and you have dynamic motion of equal amplitude and opposite phase at some particular speed; it is conceivable that a monitor would read near "zero". The opposite situation would be where the peak of dynamic motion and the runout are in phase which... [ more ]
Registered Member I am adding a new comment to an old conversation. We have some rotors that have total M/E (Mechanical/Electrical) runout of 0.00034 inches. I just got these numbers today, and haven't thought about it long enough yet, but I'm wondering if there's a way to predict the amplitude of vibration, all things being equal. I think I already know the answer to my question is, "No.", but I just thought I would ask. [ more ]
Registered Member Its a centrif pump & i think rotor diff temp would not go more than 90F. With 0.000012 coeff Im seeing around normal 4mil exp assuming sleeve temp is stationary. I'll double check and see if we can increase thickness for tensile tomorrow. Its bed time 12am here. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Connecting two ADRE 208Ps
RM Registered Member
Registered Member Opening the unit should not normally be needed for any reason. It was just the erratic behavior you reported that made me make that suggestion. The 208’s were very rugged units, the boards should you need to pull them have white levers at the front of the unit that assist in removal. [ more ]
Registered Member Quite an amusing mistake on my part. I was looking at the BNC connections from the top down, not directly at the terminals. The 408 numbers the channels across the row, 1-8 horizontally. I had forgotten that the 208 numbers the channel pairs in columns, 1-2, 3-4, etc, from left to right. So when I had connected the first 4 channels, I had only connected channels 1, 3, 5, 7, not realizing that's what I had done. Looking from the top of the unit, from the front, I could only see the BNC... [ more ]
Registered Member There isn’t any requirement for 8 channels. What you might try is (1) probe, one cable, and move it channel to channel, enabling the channel as you go and see the pattern. At some point you might open the case as I mentioned before and slightly extract and reseat each of the boards. As I recall, I think one board covers channel 1, 3, 5, 7 and the other 2,4, 6 and 8. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Usb-to-parallel port for ADRE 208P
RM Registered Member
Registered Member Yes, sir, I did. As soon as I insert the Quatech card, the laptop crashes and reboots. I reviewed your instructions and carefully checked the other tabs, which you indicated are for information only. I noticed that the I/O Range and IRQ both had "?", even though the driver successfully installed. I changed the configuration manually, and then changed it back to "Use Automatic Settings". After a reboot, Windows properly assigned the default settings. That seems to have fixed it. I'm now... [ more ]
Registered Member Did you follow the instructions that I linked to? What make/model computer? [ more ]
Registered Member John, you're spot on! Thank you for the help. After I posted my comments, I found this: Advantech-bb (Quatech) https://support.advantech-bb.c...;page_size=10#Driver I didn't realize that Advantech aquired Quatech, and I kept skipping over that search result. The issue that I'm having now is that the computer with ADREWIN keeps giving a fatal error (blue screen) whenever the Quatech card is inserted. Is there a way to install the driver without having the card installed? I was able to install... [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Unknown Vibration frequency
RM Registered Member
Registered Member To my list of desirables, and Shurafa’s, add some information about the coupling. [ more ]
Registered Member There are several possibilities. To avoid guessing, more data would help. For example, bearing details, crossectional drawing, overall trends, spectra from other points on the machine etc. Possibilities: 1. Resonance : can you do an impact test? 2. Misalignment : can you check the shaft and other alignments? 3. Blade pass : can you verify how many blades are in the impeller? 4. Bearing defect : can you collect high-resolution data to confirm the frequency? Regards- Ali M. Al-Shurafa [ more ]
Registered Member Can you share some details about the fans? Bearing types and if rolling element, bearing numbers. I’d also like to see a spectrum from about 0 to 10000 cpm. Obviously from your initial data, there seems to be little of interest beyone 12000 cpm, but that area less than 10000 cpm may be of more interest when expanded, [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Speed sensor for a CSI 2140
RM Registered Member
Registered Member Agree speedvue is the absolute best, even with out reflective tape shooting a key can be uses as tach [ more ]
Registered Member The CSI Speed Vue works great with a reflective tape I have used it from 50Ft away. I also have 2 of the CSI 404 that I don’t bother to use anymore [ more ]
Registered Member I use a Monarch 200 Laser Tach, it has a TTL output and a female 1/4" 20tpi mounting for a tripod or mag base. CTC has the cable you need to hook to your 2140 https://monarchinstrument.com/...ocket-laser-tach-200 [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Motor's high vibrations on vertical pump unit
RM Registered Member
Registered Member Hello Mr Dave. Thankyou for share many information. In my site have same problem withthe author publish. The Vertical Pump with install side by side. Amplitude was high in NDE Motor Vertical Axes, The Spectrum show 1x Order Motor speed : 1485 rpm [ more ]
Registered Member John my experience with the equipment you referenced was for the most part very enlightening. [ more ]
Registered Member I like the timber approach if you are not doing a real modal. This can put real energy into the lower modes. I used to use a little larger cross section if I could find it. Use the end. Swing it like a bat and see how that works for you, not my preference. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Why one of either eddy probes (X) gives high vibration reading compare to another (Y)
RM Registered Member
Registered Member UPDATE , another link to that article can be found at What Are Orbit Plots Anyway . But read below for related content that may prove of interest. I suggest you just post a new topic on the forum with your specific details and then gather new information. But something that might prove of interest can be found at https://www.bakerhughes.com/si...it_v30n1_2010_q4.pdf . See the content titled "Are XY Radial Proximity Probes Really Necessary?" Another related article can be found at... [ more ]
Registered Member @Registered Member - The posted link is broken.... do you have another link where we could download the information you intended? Thanks so much. KB [ more ]
Registered Member Gents, I'm also facing a similar issue in one of the probes the vibration is high in fact except this high vibration reading the entire machine has no other alarm. Location is DE side (X) of a centrifugal compressor. During opportunity of Driver overhaul. 1.Probes has been newly replaced. 2. (tilting pad bearing) has been inspected and found normal. 3. Alignment verifed with OEM (GE) specifications. still after startup the vibration is trending up in one particular orientation. *attached data [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Steam turbine vibration in high frequency
RM Registered Member
Registered Member Can you share those spectrums in log scale? [ more ]
Registered Member Without knowing some details, the comments would be guesses. If I were you I would start by confirming that the data represents the machine's condition (i.e. the signal on the screen is not from something else). For example, put your hand on and have a sanity check by feeling the vibration. An amplitude of 2.4 mm/sec 0-p at 148,000 cpm is so rough to be missed by hand. Do use another sensor/mounting, change the location slightly, etc. If it's an authentic vibration from the machine, collect... [ more ]
Registered Member Just an FYI, Kevin Z, the OP, hasn't been on this site since February of 2021. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Resonance problem
RM Registered Member
Registered Member Do you have the capability to do a modal analysis? Or at least an Operating Deflection Shape? It would be very helpful to understand the mode shape of the resonance. By understanding where the nodes and anti-nodes are it may be a more effective way to know where to add/decrease mass and/or stiffness. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Emonitor Odyssey
RM Registered Member
Registered Member That's actually funny. 4.1 in a couple of weeks, I wouldn't hold my breath. They have been promising the emonitor windows version AKA 4.1 for over 4 years now and still nothing. The support is there for 1444 modules however in their infinite short-sightedness, the handhelds will not be supported. I was actually thinking about flashing SKF GX's with Entek firmware to see if they would work as most of the Enpac 2500's suffer from plastic failure after 20 years. I truly wish I could buy this... [ more ]
Registered Member But is not dead yet. RA will release emonitor 4.1 in a few weeks. Full compatible with w10/11 and modern MSSQL Database versions. [ more ]
Registered Member I shudder to think how many are left in the lurch with emonitor. Probably the best software developed for con Mon but sadly greedy Rockwell ruined it and then abandoned it. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Integrally Geared Compressor Overhung Rotor High Vibration & Balancing
RM Registered Member
Registered Member Do you have any orbit/timebase plots at low RPM, preferably a shutdown? Also, you mentioned that the "...direction of rotation is from X to Y". In the Bently convention, you "view" looking driver to driven. That means if the prime mover and gear is X to Y, then the pinion has to be Y to X. Is that set up properly in Sys 1? [ more ]
Registered Member Hi John Thanks for useful inputs. Unfortunately, I couldn't personally verify the Probe configuration as I was stuck with other site activity. As per feedback from Instrument & Vibration Team it has been done as you have recommended i.e., Probes were disconnected at machine and then checked at System-1. The Compressor was stopped for this activity (it has standby and was still running in parallel with other unit to ensure its reliability, so it was handed over for Probe verification... [ more ]
Registered Member This could be dynamic activity but in the instance of reverse precession both ends I would be inclined to carefully check probe configuration. And I'm well aware that you say it has been checked already. Over my career I've found many an item that had been verified, but unexplainedly was found to be incorrect when I personally checked it. In addition, by configuration, I don't just mean in software, I mean from hands-on identification of the physical probe at the machine and tracing it back... [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
High Vibration from fan bearing housing
RM Registered Member
Registered Member Based on your identified bearing fault frequencies, it looks like there is a bearing fault! I am not be surprised that adding grease offers no sound reduction. I would expect that measurements with an ultrasound meter (with headphones) would confirm bearing fault, if necessary. When you replace the bearing at a convenient time, then you could also inspect condition of the shaft coupling and do precision shaft alignment. Any machine with VFD motor control is suspect for accelerated bearing... [ more ]
Registered Member Yes we did inspect the spider and did the greasing of bearing still the noise level is high [ more ]
Registered Member When was the last time the jaw type coupling was examined? This type coupling often has a rubber insert called the “spider” and these do degrade over time. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
URGENT HEAVILY ELLIPTICAL ORBIT ON BARREL TYPE HIGH SPEED COMPRESSOR
RM Registered Member
Registered Member @Prabhu, you may never find out "the findings" for the original post. Take note that the OP last visited this site on 10/6/2008, some 15 years ago. You can get this type of information by floating your cursor over a person's name. I'd also suggest that in the future, if you see an old thread that is related to one of your problems, read the content and learn from it, but then start a new thread specific to your problem. As to your readings, I personally don't see an immediate concern over a... [ more ]
Registered Member Gents, What was the findings? Now we are facing exactly same issue. one of the probes the vibration is high in fact except this high vibration reading the entire machine has no other alarm. Location is DE side (X) of a centrifugal compressor. During opportunity of Driver overhaul on the compressor side we checked and 1.All Probes has been newly replaced. 2. (tilting pad bearing) has been inspected and found normal. 3. Alignment verifed with OEM (GE) specifications. But still after startup... [ more ]
Registered Member As John suggested, a picture is worth a thousand words. Plots from before and after the maintenance activities could be useful. Did bearing and coupling inspections reveal anything, and were any parts replaced? [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
urgent advice
RM Registered Member
Registered Member Thank you for replying. i think mobius is good if you pay for their certification. I found a solution. there is a 3 hours long video by grace technologies explaining vibration analysis from scratch that is so good. feels like they covered most of the topic. and when i encounter difficult contents from video, i go for book azima dli a friend recommended above. i will try to get foundamental knowledge, theories and reading trends so on then i will ask my company to rent an emerson analyzator... [ more ]
Registered Member https://www.youtube.com/result...ght+mobius+institute Mobius offers free youtube videos Dave [ more ]
Registered Member thank you! Yes this forum is very helpful. i thought nobody would get back to me after sharing this post but luckily it is very good place [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
1x High Vibration NDE Motor
RM Registered Member
Registered Member a couple of motion amplification videos to show the movement of the base. which is allowing the motor to move a lot more than what is acceptable [ more ]
Registered Member Why use peak hold averages spectrums if you can make waterfall plots, in my opinion 1000hz 400 lines will give you a very fast spectrum and any other harmonics will rise at a resonance "zone" which will give you a better confirmation of resonance Agree with Ralph, phase at feet and what's this motor driving, motor - gearbox - rollers for a pellet press, how is the feeding "controlled" more material will slow down the motor (increased load) once the motor is free it will spin a little faster,... [ more ]
Registered Member Thanks James. This is sort of strange for there to be sidebands off the 1x at such a CLOSE distance........ What is the motor driving, a gearbox? and what is the final rpm of the driven part? If agitator, what is its rpm snd how many blades or paddles? Ralph [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Roller Bearing in Motor
RM Registered Member
Registered Member You are replying to a thread that is almost 9 years old. [ more ]
Registered Member The pic in the docx *absolutly IS Brinneling. 100%. True Brinneling I belive. This means the charge is too light. [ more ]
Registered Member Dan, attached is the docx file converted to PDF. What version Word are you using? Even my Samsung Tablet opens docx files without any issues. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Motor high vibration in 2X Velocity and high Envelope value
RM Registered Member
Registered Member Did the motor ever run smooth or at lower vibration levels? Did the motor ever show a high 2x before? Does the driven component also show a high 2x? Have you done any phase analysis of the motor? As others stated, if the repair work to the DE of the motor was done incorrectly, this would cause permanent misalignment inside the motor and not show misalignment problem on the driven component/across the coupling. The NDE H and V axis have high 2x, notice at the very base of the 2x there is a... [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Excel Balancing File
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Registered Member Rev. 8 correction balancing file [ more ]
Registered Member John That's correct. Just so members dont download the rev. 7 without making the correction, It is more appropriate to simply make the correction and call it rev 8 I will download it after this post Regards Jim P [ more ]
Registered Member If you review the thread, you will find versions up to Rev 7, the latest to my knowledge. Having said that there is a correction that is described immediately after the post with the file. Make sure you incorporate that change. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Overhung Fan High 1x Horiz DE fan Bearing
RM Registered Member
Registered Member Just thought I'd add what I've tried so far. We managed to find a gap for an hour's downtime and I did as many tests as I could in that time. Firstly no imbalance from the fan, shaft check with dti gauge and it's straight. Pulleys in good condition. Motor checked and it has a stiff rotation before becoming loose and then tightening up. Think this may be where the problem lies. Attached is a motion Amplification of the fan [ more ]
Registered Member quite well known problem for me. It is beating as the other colleagues said. Change the pulley ratio and you sovle the problem otherwise the only thing you can do is try to balance the best possible both pulleys. Ruben [ more ]
Registered Member James, I would suggest, to supervision, separating the speed of the fan from the speed of the motor, from being a 1 to 1 ration, by changing the pulley size. If it were direct coupled to the motor, this problem would very possibly, not be there. Surely, with it being an air exhaust fan, the fan could be slowed down or increased by 20-50 rpm's or more, unless it must rotate, by law or design, at a minimum of 1480 rpm. If the fan must run a minimum of 1480, I would suggest increasing the fan... [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
VFD driven cooling tower fan
RM Registered Member
Registered Member Hi John, thanks for your input. It's a vertically oriented direct coupled VFD-driven motor, gearbox, and fan unit. Yes, the vibration levels are now 1-1.2 mm/sec RMS tested at different speeds between 800-1300 RPM. I read some papers regarding VFD-influenced harmonics and torsional vibration, trying to understand this as I haven't come across this type of issue before. Appreciate if you can share a practical experience or elaborate on the torsional effect. Thaks. [ more ]
Registered Member Hi Dave, apologies for the late reply, I had some busy days with the shutdown. Yes, 1x fan/motor speed varied with the speed change and position 3 is the gearbox input. Both the motor and gearboxes are recently refurbished, and all the results are within acceptable limits with the workshop acceptance testing (load test). It's a vertically oriented direct coupled VFD-driven motor, gearbox, and fan unit. We have five and vibration velocity levels are between a-2mm/sec RMS. Vibration levels on... [ more ]
Registered Member What is the arrangement of the cooling tower? I have often see the towers utilizing a right angle gearbox have a 1-node torsional around the 10 Hz to 12 Hz region. Noting your comment "The vibration amplitude came down to a normal level after the 2nd VFD replacement", did you see a substantial amplitude change at 900 RPM and or 1100 RPM? If so, a torsional effect may be having some influence. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Vibration value discrepancy between ADRE and HMI
RM Registered Member
Registered Member There could be many reasons for amplitude discrepancies. However, I tend to agree with @Registered Member to start by comparing the configurations. Fmin, Fmax, rms, 0-p, type of sensor, power, and scale factor are possible factors to cause discrepancies. I also found very few cases where the rack cards had internal issues. If you have a shaker table or a signal generator, they can be very useful to troubleshoot the case. What do the waveform and spectra contain and are they stable? I guess... [ more ]
Registered Member What is the exact make and model of the accelerometer? Which ADRE are you using; the 408 DSPi or the much older 208P? In the interim, make sure the ADRE and the HMI interface are both configured for the same units. You don't for instance want one configured for RMS and the other PEAK. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Rotor bow ge frame 5 gas turbine
RM Registered Member
Registered Member In my opinion 1 hour may be far too short a time. It could take a day. I've seen results in 4 hours, but if you have the time let it roll. [ more ]
Registered Member We haven't made any inquiry. We just referring to operating manual which mentioned if your shaft suspected to rotor bow , turning at least one hour turning gear . We have done it but vibration has not decreased . Can we conclude bended shaft or permanent bowing ? [ more ]
Registered Member If you have been down since the time this was posted, this would be a cold start. Borescope cannot see all places that the turbine can rub; on gear you may be able to hear a rub--you might go in the exhaust or inlet (if it is not deafining). Not seeing any rubs, is a good sign to place the unit on turning gear (jogging, whaterver you have). (Once someone described to me the rubbing sound on a turbine as whales mating--I wonder how they knew.) You do not have a specific procedure from the... [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Predictive Equipment Checkout Aid
RM Registered Member
Registered Member Thank you Mr. John I prefer to not reinvent the proverbial wheel so I will give that a look see. [ more ]
Registered Member You might want to look into getting a copy of API 686 Recommended Practice Machinery Installation and Design. There are machinery commissioning checklists in Chapter 9, although as I look at what I have it is the 1st Edition (April 1996). The 2nd Edition is from December 2009 and it was reaffirmed in November 2014. It's about $200 but it is a very comprehensive document on installation and design. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Sub-Synchronous Vibration (1 - 2 Hz) problem. Electrical noise or Fluid Instability? HELP!
RM Registered Member
Registered Member The time waveform looks to have a transient at the start of data collection. The meaning of the spectrum is questionable because of this. Does this repeat? With other data? There could be a number of causes. One is a sudden application of the transducer concurrent to the start of data collection. Don't be too quick to collect data after placing the transducer. [ more ]
Registered Member Can you elaborate on what you are referring to when you say “vibration transmitter”? Are you truly using a transmitter or are you using a proximitor wired back to a rack? Perhaps add make and model. [ more ]
Registered Member Yeah, I think the problem is more about noise but instrumentation personnel has replaced cables, sensor, vibration transmitter and the problem still continues. The barrier was also eliminated. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Turbine journal bearing High temperature
RM Registered Member
Registered Member I dont have extensive field experience with gas turbines (others on this forum do), but it seems to me that the orbit displays you provided shows a very high preload in the horizontal direction <--- assuming the 0 deg reference is the top/vertical direction. Do you have orbits and vibration data from before recent inspection for comparison? Orbit shapes will change with speed (and perhaps load) due to the accompanying dynamic stiffness changes. It would be nice to plot these various... [ more ]
Registered Member hello Mr Jim thank you , in above my answer for your question. attached is the alignment report. Regrads [ more ]
Registered Member Am a bit confused....you say X and Y radial plan(e) but axial proximiter? Can you confirm we are talking radial measurements or axial "thrust" measurements On initial glance, this data appears to show your orbit shaft highly preloaded in 0-180 deg direction. Not sure how you set up your probes so I am assuming the horizontal direction. Since you state it was only an inspection, I would assume no work was done to it? yes/no? I would check carefully how you replaced the bearing after... [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Pfaudler Gearboxes fault frequencies
RM Registered Member
Registered Member Contacted the number provided and spoke with the service manager. Found out that the individual that I had previously spoken with works in her group. More to follow..... [ more ]
Registered Member I’d call the number I previously provided and ask to speak specifically to the service manager. [ more ]
Registered Member Thank you Mr. John. To be honest I am not sure where the gentleman is out of that I was speaking and am in email contact with. I was given his name and contact information by a Field Service Coordinator from GMM Pfaudler US. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Marley 2200 gear reducer GMF
RM Registered Member
Registered Member Thanks for your help [ more ]
Registered Member Something wrong…1457/210 = 6.938 but up front you said the ratio is 6.12:1. Verify the speeds, confirm this is a single reduction and see if you can get any info that would confirm seven teeth on the pinion. [ more ]
Registered Member This is a spiral bevel. Output speed appears to be about 210 rpm. [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Shaft journal surfaces for proximity probes
RM Registered Member
Registered Member John, Thank you. Your response is close to what I was thinking, but it is always advisable to get the opinions and thoughts of those folks that know the territory the best. Best Regards, Ron Brook Sent from Mail< https://go.microsoft.com/fwlink/?LinkId=550986 > for Windows [ more ]
Registered Member Ron, chrome is an acceptable method of repair with some caveats. When journals are in need of repair it is common practice to turn them down to some undersize dimension, plate the area with chrome or perhaps tungsten to an oversize dimension, and then grind the area back to the proper dimension. Using proximity probes in the repaired area commonly results in indications of excessive vibration that are not related to the actual dynamics of the rotor. Understanding the problem is relatively... [ more ]
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Asset Condition ManagementPosts About vibration/alignment/balance
Discussion about phase behavior
RM Registered Member
Registered Member Probably the balance of the motor is good. I just was curious if the same base and lower vibration was due to uncoupled or different base. Anyway, I had experience with a screw compressor, improving alignment improved the axial vibration, I could not find a solution, I think the problem was in the screws itself, but the motor had lot higher vibration than the compressor side [ more ]
Registered Member Thinh Pham , Here is an early post along the lines of your questions. Looks like it might be from 2010 (12 years ago) It has a few more members responding. But appears to say, more or less what the current replies say. In my opinion, in most cases, phase is not an absolute, "fix-all" tool. Just another tool used with an open-mind when in the search for the real problem. https://www.maintenance.org/to...about-phase-behavior Thanks, Ralph BTW: The balance might be from the driven machine and... [ more ]
Registered Member The solo was not in the same base [ more ]
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