Tagged With "1x"

Topic

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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Finish Mill Stand Gearbox

Phil2425 ·
I am seeing 1x impacting in waveform data from a gearbox. We have opened the box up to replace a faulty bearing. We inspected the gearsets and did not find any signs of broken or cracked gear teeth. I know that other stand and other mills have a 1x...
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Finish Mill Stand Gearboxes

Phil2425 ·
I am seeing a 1x vibration in our Finish Mill Stand Gearboxes. I know that a broken or cracked gear tooth will cause this issue, however we have opened up a box and did not see ay signs of a cracked or broken gear. Some of our other stands...
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Synchronous motor 2x verse 1x vibration amplitude

Rick Raymer ·
We have a 4000 hp, 400 rpm, 13,200 volt, synchronous motor.  The motor was just rewound and during no load testing we identified the 2x vibration amplitude was significantly higher ~4x than 1x.  Keep in mind the overall vibration amplitude...
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“STRANGE” FIRST ORDER (1X) ON FAN SYSTEM

dominich.vo ·
Hi all, I would like to discuss one case in fan system. This is MV wound rotor . Nameplate speed is 16.33 Hz (980 RPM) . However, in spectrum data indicate peak at first order is 15.25 Hz (~915 RPM) . This is so strange with what I learn about...
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Vibration at 3.1x order in Motor

SHANS ·
Hi We are currently facing a high vibration issue in one of our Oil water transfer pump motor (Horizontal pump) in our midstream facility. Its a 45 KW (Make:Loher) motor running at 1475 RPM. Both DE&NDE bearings are 6316 C3. Motor NDE : H- 1.0 mm/s, V-4.5 mm/s, A-3.7 mm/s Motor DE : H- 1.2 mm/s, V-2.7 mm/s, A-3.9 mm/s Motor is showing very clear distinct non-synchronous peak at 4560 cpm (3.1x) and minor peak at 9120 cpm. (Checked with high resolution spectrum also)...
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Re: Synchronous motor 2x verse 1x vibration amplitude

Edwin de B ·
As this is a synchronous motor, 2X is also the 2FL (2x power supply frequency). So you can check on softfoot / distorted casing.
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Re: Synchronous motor 2x verse 1x vibration amplitude

Rick Raymer ·
As noted in the posting, the motor rpm is 400 rpm. No vibration energy was noted at line frequency or 2x line frequency.
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Re: Synchronous motor 2x verse 1x vibration amplitude

Edwin de B ·
Ah, I see. Excuse me. Wat is the relation between axial and radial amplitude? And between the two sides radial DE and NDE?
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Re: Synchronous motor 2x verse 1x vibration amplitude

Ron Brook ·
Have you checked the bearings to ensure proper installation? A cocked bearing would generate a 2x.
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Re: “STRANGE” FIRST ORDER (1X) ON FAN SYSTEM

John from PA ·
A wound rotor induction motor has a stator like the squirrel cage induction motor, but the rotor windings are connected through slip rings to external resistances. Motor speed may be varied by varying the resistance in the rotor circuit. Usually speed control technique is useful over a range of 50% to 100% of full speed. Often the controller uses wire-wound resistors that are progressively shorted out manually or by magnetic contactors controlled electronically. Relatively new wound-rotor...
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Re: “STRANGE” FIRST ORDER (1X) ON FAN SYSTEM

dominich.vo ·
Hi John. I do not think so, rotor always connect with a resistance system but after start-up,Magnetic contactors close by-pass to remove liquid resistance out of rotor system. I also do more MCSA _online test, the effective (95%) and power factor (cos(phi) = 0.9) are still high. I do not think that is controller issue.
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Re: “STRANGE” FIRST ORDER (1X) ON FAN SYSTEM

Edwin de B ·
Could it be that the by-pass circiut has some resistance? The 15.25 Hz is definitely the 1X and indeed that means a big slip on motor rpm.
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Re: “STRANGE” FIRST ORDER (1X) ON FAN SYSTEM

nugrous ·
I agree with Edwin de B. 15.25 Hz is definitely the running speed of the motor and the driven. It is obviously indicated on the spectrum of the driven you sent. Your motor has a big slip problem. Some factors could contribute to excessive motor slip. For example: the load of the motor (fan) or the abnormal voltage. You could check the motor load from the current. High ampere means high load. High load can increase the slip. The motor slip also increases proportionally to the square of the...
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Re: Finish Mill Stand Gearbox

John from PA ·
What I see is an overall of 0.0641 in/sec pk, which is not alarming in itself, but I do see a crest factor of slightly over 4. Is this behavior something recent or has this been this way for some time? Any idea is there has been an upward trend of the crest factor? Can you take the gearbox out of service and inspect the teeth using a dye penetrant method? Audibly, does the gearbox have a pronounced "knocking".
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Re: Finish Mill Stand Gearbox

Phil2425 ·
There is not an audible knock. You can just feel a 1x thud when operating. We changed spindle components and it got somewhat better. Just very curious as to what it is.
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Re: Finish Mill Stand Gearbox

Phil2425 ·
The Crest Factor has always ran between 3 - 4.
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Re: Finish Mill Stand Gearbox

John from PA ·
Is the behavior of the impacting in the waveform something recent? Or perhaps first time observed? In light of the overall amplitude of 0.06 I'd be inclined to just watch carefully. However, if that evidence of impacting in the waveform just suddenly started I would have some concerns. By the way, what are the speeds and tooth counts of this gearbox?
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Re: Finish Mill Stand Gearbox

Bill Kilbey ·
Take some PeakVue readings, it may be much more clear.
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Re: Finish Mill Stand Gearbox

Ramos_ ·
Looking at the TWF, there are 3-4 teeth that is creating modulation that is why they appear like as 1X peak sidebands on the FFT and also look like an impacting. Crest factor will also be increased as Pk is getting higher than RMS reading (CF = Pk/RMS), especially when there is impacting. For this case, some recommended actions can be: 1. John's suggestion is good if it's possible. I worked in Cement plant before and periodically we stopped cement ball mills and can do inspection. Boroscopic...
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Re: Finish Mill Stand Gearbox

Phil2425 ·
I have been taking Demod data and there is no signs of impacting or defects in the high freq data.
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Re: Finish Mill Stand Gearbox

Bill Kilbey ·
Can you post that DEMOD or PeakVue TWF data?
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Re: Finish Mill Stand Gearbox

Monitor man ·
Originally Posted by Phil2425: I am seeing 1x impacting in waveform data from a gearbox. We have opened the box up to replace a faulty bearing. We inspected the gearsets and did not find any signs of broken or cracked gear teeth. I know that other stand and other mills have a 1x during operation. Does anyone else have any experience with this. If you have a cardon shaft check the u-joint cross can be damaged. There for the "clear" time signal
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Re: Synchronous motor 2x verse 1x vibration amplitude

Aditya ·
4000 HP, 400 RPM would probably have sleeve bearings. Not sure if you can have a cocked bearing in those. Have you taken vibration data in coupled no-load condition or in decoupled condition? Regards, Aditya
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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: Vibration at 3.1x order in Motor

Steve Ciesla ·
I think Rusty is right on here. What does the data tell you? Watch the TWF amplitude (maybe crest factor if you prefer) for changing conditions. With an BPFO, you may be dealing with an oval bore that is squeezing the bearing.
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Re: Vibration at 3.1x order in Motor

Danny Harvey ·
My experience is that when the first harmonic of bpfo is that big there is something forcing the outer race into an abnormal position. Like a bearing cocked on the shaft or axial preloading. If it doesn't show in your PV data, I would take a look at your filter settings. Why are you using sst on a 1485 rpm bearing?
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Re: Vibration at 3.1x order in Motor

Bill Kilbey ·
Yep, Danny, cocked or slightly tight/out of round. Possible skidding from not enough load too. Common in repair shop or uncoupled run.
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Re: Vibration at 3.1x order in Motor

CSG ·
I am not able to open the attachment Word file. Can you send the file to my mail csgk53@yahoo.co.in ? As axial vibration is high and the high first harmonic of BPFOis also high, my take is that outer race is in distress or alignment is suspect. I do not know what did the attachment contain. Pl send it to me for more information on the problem. Please send a Word file.
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Re: Vibration at 3.1x order in Motor

SHANS ·
Thanks all for your replies. My impression too was bearing outer race issue. But I need to get some supporting information before recommending for inspection. I will update you with more new data soon. shans
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Re: Vibration at 3.1x order in Motor

cnu ·
Yes it was indicating outer race defect but once ensure that the clearance b/w bearing & motor bore is matching or not.. otherwise just adjust the clearance of bearing the problem will sort out Hope it was helpful....
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Re: Vibration at 3.1x order in Motor

Edwin de B ·
This fenomenon is seen by me often. It is indeed an oval shaped outer race. Most of the time it results in lower levels of vibration and i leave it as it is. In your case velocity is quit high and it will reduce the life span of the equipment. You can leave it as long as the lubrication stays allright. If lubrication fails you will find more noise around 3 kHz / 180000 CPM in acceleration spectrum. But as i said: this vibration will speed up normal wear. So if you can, inspect and correct...
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Re: Vibration at 3.1x order in Motor

Mihai.Luchian ·
Make sure the speed of the motor is correct. Such peaks in mm/s are not very common so maybe it is a sinchronous frequency coming from the coupling or the pump rotor.
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Re: Vibration at 3.1x order in Motor

Mihai.Luchian ·
Oh, I just now took a closer look to your spectrums. They are axial and vertical. It is not the bearing my friend. 100%. Is it a belt driven pump?
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Re: Vibration at 3.1x order in Motor

lintu ·
The BPFO you found is still acceptable. You can run it for a couple of weeks. Trend it well. In considering replacing a bearing, whenever you saw an increase in amplitude in the bearing forcing frequency.
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Re: Vibration at 3.1x order in Motor

seandude ·
I've seen 3x problems many times at my plant. Your "3.07" is close enough. Here it most often a 3 jaw coupling failure or a soft foot on the motor. I resolve soft foot problems by looking at a live view FFT and then loosen one motor hold down bolt at a time (while machine is running) to watch for the 3x amplitude decrease. Then shim it. Good luck and please keep us posted regarding your solution.
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Re: Vibration at 3.1x order in Motor

seandude ·
Originally Posted by Rusty Cas: No, 3.07 is not "close enough" to 3 to call it 3X. If you have ANY spectral peak that you think is a "problem" then you are a poor analyst if you don't confirm the actual frequency with a high-res spectrum. Making assumptions about frequencies wastes time and money, and ultimately gets you into trouble. Look up BPFO for a 6316 bearing. How much time and money does it waste to check for a possible faulty 3 jaw coupling insert? Or a soft foot check that takes me...
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Re: Vibration at 3.1x order in Motor

Mihai.Luchian ·
Seandude, finally a pdm engineer arised. Please send me your email adress. It was very nice meeting you here. I would advise everyone else who wrote on this post to start READING. NOW!
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Re: Vibration at 3.1x order in Motor

Barry ·
Mihal what are you wanting them to read?
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Re: Vibration at 3.1x order in Motor

IrishMark ·
I get the distinct whiff of Troll(s) in the air.
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Re: Vibration at 3.1x order in Motor

seandude ·
Originally Posted by Rusty Cas: Sean (or is it Dude?), no less than 7 experienced analysts say it's an outer race defect for the 6316 bearing in this motor, which the OP confirmed was 3.1x with a high-res spectrum. There wasn't mention of a 3-jaw coupling which would be unusual fora motor this big anyway. We have seen this many times. No one said the bearing was "bad", just that there was a defect. You can have a defect without sidebands or harmonics, just pure1X BPFO. No one said to pull...
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Re: Vibration at 3.1x order in Motor

Danny Harvey ·
I've already had enough of this. Goodbye.
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Re: Vibration at 3.1x order in Motor

Mihai.Luchian ·
Dear colleagues, I whitnessed hear people that based on some velocity spectrums and a few words knew EXACTLY what was wrong with the bearing. The initiator of this topic started offending the first person who had another opinion. I don't think that this is a correct attitude when you ask for help. Somebody tries to open your eyes and you start offending him just because he thinks different. I preffer to read, the topics, the answer, some literature and I realized that the only pdm engineer...
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Re: Vibration at 3.1x order in Motor

Bob/MVS ·
Hi Shans I was unable to download your attachment - however looking at your values, frequency of concern and accepting you did carry out some high res data to confirm a 3.1xrpm Vs a 3.0xrpm - then I am of the same opinion here with regard to it “possibly” being an outer race issue. ( based on your findings as posted here and with respect to the bearing being a 6313 ball bearing ). Offering my opinion here, I have seen many issues with a bearing outer race frequency being the dominant...
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Re: Vibration at 3.1x order in Motor

zhouyh ·
I once saw a motor guy how to deal with 3.08x on a 30 kW motor. He tried to give the motor shaft a axial knock from non-driver end with copper bar. It worked. Regards.
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Re: Vibration at 3.1x order in Motor

SHANS ·
Big thanks to everyone who spent your time to provide valuable hints. Apologies for the delay in responding. seandude Its flexible membrane spacer coupling. There is a 135 cpm difference between my 3.1x forcing frequency (4560 cpm) and 3x (4425 cpm). This is confirmed as mentioned in my original post. Mihai.Luchian This topic has come all the way for discussion just because of its peculiarity (Non-synchronous peak, but severe in axial direction, sinusoidal peak) as I put forth in my original...
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Re: Vibration at 3.1x order in Motor

Mihai.Luchian ·
I thought Rusty Cas was starting the topic, he offended sean dude. I still think that velocity is not the method to see bearing damage. This is basics. Go with a strobe, check the speed of the motor, check your spectrum resolution so you don't get an error from that and look for your problem soewhere else. Do you have an acceleration/envelope spectrum available? That's where the bearing problems are very visible and trendable. All the best to everybody and if anyone felt offended by me, that...
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