Tagged With "phase"

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5MW 3phase motor, Single phase overload trip

Lampard Nguyen ·
Dear Experts, We have 6.6KV wound rotor motor, 5MW, 500A FLA, cement milling motor. For 2 years operating, about 1 month to 2 months operating, motor is trip by single phase overload (always random 2 phase ~ 450A, 1 phase ~ 1000A).  We have...
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2 Plane Balancing without phase

Avinash Thawani ·
2 Plane Balancing without phase How else is it possible?
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Cross Channel Phase Analysis

Pump Guy ·
I recently identified root cause of high vibrations on a horizontal pump. Amplitudes at PIH & POH locations exceeded specification limit. I did cross channel phase analysis using CSI 2140. Phase angle difference on pump feet and pads (vertival direction) was 170 degree. This indicated they were moving out of phase. I loosened one hold down bolt and the 1X peak amplitude dropped from 0.40 in/s to 0.20 in/s. I used monitor mode of the device and loosened second bolt and the 0.2 in/s 1X...
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Cross Channell Phase Analysis with CSI 2140

NewVibeTech ·
Has anyone tried Cross Channel Phase Analysis with the Csi 2140? I tried with no success and I'm wondering is it a special cable needed to do this? Anyone with any experience using the 2140 for phase please let me know how this was done. Thanks in...
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Cross Phase analysis issue

Hossam 2 ·
Problem is in motor if atox mill (insaldo) The free end has a 4xts dominent vibration we have balanced it to reduce one x from 3 to 0.3 mm/s vut still over all value is 5.5mms wiz 4xts sharp  The phase relationship is weired as 180 phase difference between the drive end and non drive end in the vertical direction ..i suspect misalignment problem and the other issue is that no sensors give exact reading across the coupling specially in the gearbox side always give real value in the motor...
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ODS - wire model move, problem visualization

czJKr ·
I discovered that there are multiple approaches for creating an ODS moving "wire" model. ODS data for model can be collected easy as amplitude and phase angle on problematic frequency (1x). Second approach return few spectrums datas (FFT, Coherence,...
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Phase Analysis with SKF Micolog

ALI HAIDERR ·
Dear Experts, I was user of CSI and got cross phase data 0 -180 degree which can be applied for diagnostics. But now i am using SKF Microlog and getting cross phase data e.g.257 degree,330 degree etc.I believe cross phase data should not be greater than 180 degree.May I correct?and what I understand by SKF cross phase data which may be greater than 180 degree. How can I take results by this data? Thanks
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Re: 2 Plane Balancing without phase

John from PA ·
Not sure what you are driving at but lacking phase, there is the four-run method. Do a search and you'll find discussion. Otherwise, clarify your question.
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Re: 2 Plane Balancing without phase

fburgos ·
interesting a 7 run method, for educational pruporses its fine, for reliability use phase method.
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Re: 2 Plane Balancing without phase

William_C._Foiles ·
The attachment shows how to balance in any number of planes you like. If you like you can do optimized balancing such as least squares.
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Re: Cross Channel Phase Analysis

Lou Pag ·
I am glad that the problem was solved. I am assuming that since your excessive amplitudes were at POH and PIH these are the locations where the 1X amplitudes dropped off when the bolts were backed off. I say this because you did not specify. The 170-degree phase difference was in the verticals as stated but not in the horizontals. The induced stress due to the soft foot does not allow much amplitude at 1X at POV and PIV but why the 170-degrees difference between POV and PIV? Here is why. You...
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Re: Cross Channel Phase Analysis

Pump Guy ·
Lou Pag, Thanks for your valuable comments!
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Re: Cross Channel Phase Analysis

Lou Pag ·
You are welcome.
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Re: Cross Channel Phase Analysis

seandude ·
Foot related resonance is very common. I have found that I can lower vibration significantly on just about any machine in my plant by loosening a hold down bolt. This is especially true for vertical pumps. I set my analyzer (CSI 2130) to monitor mode and watch the 1x frequency as I randomly loosen then tighten each hold down bolt on both the drive and driven equipment while it's running. Sometimes shimming the affected foot does not correct the high vibration. In fact, it transfers the...
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Re: Cross Channel Phase Analysis

Lou Pag ·
I have found that to be true also. If it is soft foot, I see the advantage of machining the base flat to remove it but no effect, if any, if it it is foot-related resonance. Stiffening to alter the natural frequency may be the most plausible correction . Sometimes even changing the RPM by 10% or so can make a positive difference. Or leave the one bolt loose, as you say, if it won't compromise ssfety is a possible solution.
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Re: Cross Channel Phase Analysis

Shurafa ·
Can you please advise me on how can I calculate/estimate the extent of safety risk introduced by keeping a hold down bolt loose on a typical medium size motor? In your facilities, is the case of keeping a bolt undone considered a temporary or permanent solution? Regards-Ali M. Al-Shurafa
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Re: Cross Channel Phase Analysis

Pump Guy ·
In this case, resonance was not the issue. I do not think keeping one bolt loose permanently will be allowed anywhere. One has to be very careful during this check for safety reasons. When I make this check I look at 2X peak as well. If you see increase in 2X peak amplitude, you know that the pump is moving and it is no more safe to continue with loosening of bolt. While this is a useful check but safety of people around the equipment should be given top priority.
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Re: Cross Channel Phase Analysis

Lou Pag ·
Shurafa, Common sense has to be factored in. I had one case involving a pump to that 2 mounting bolts plus a third leg under the "snout" that housed the packing gland. The third leg was causing foot-related resonance when it was bolted. To correct permanently we left the bolt loose to the leg. The machine was held in place with 4 motor bolts and the two pump bolts. Nothing ever happened. We wondered why did the designer put the third leg there. One inch closer to the 2 mounting bots would...
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Re: Cross Channel Phase Analysis

Lou Pag ·
Pump Guy, No, you did not have resonance . You had soft foot. SEANDUDE who responded had foot-related resonance. As you know, they are different. A weak base at one corner can give you a 180- degrees phase difference in the vertical between two bearings with the highest amplitude in the vertical at the bearing where the base is flexing . A distorted base at one corner will have a very low amplitude in the vertical on the bearing nearest that corner. You may see a 0-degree or a 180- degrees...
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Re: Cross Channel Phase Analysis

Shurafa ·
I completely agree. My problem is that common sense, experience etc are not the same things for different people. For instance, if "nothing" "catastrophic" happened to some machines in some cases after keeping the bolts loose, maybe this fact is not enough justification to carry out this "repair". Maybe there is a need for an MOC or a JSA. In many cases, the reason for a catastrophe not to happen is the existence of other protection layers. For the case of bolts, I guess the designers...
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Re: Cross Channel Phase Analysis

Walt Strong ·
Unfortunately Ali there is very little Common Sense being used any more. I call my services based on Uncommon Sense, since it differs from most folks who have a problem! Walt
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Re: Cross Channell Phase Analysis with CSI 2140

Kos ·
There are several video tutorials on Emerson's website. As example Collect Peak and Phase Measurements But you need to use cables from accessories package for 4-ch analyzer. For 2-ch analyzer there are right cables already in the box.
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Re: Cross Channell Phase Analysis with CSI 2140

NewVibeTech ·
You can't do Phase Analysis with the cables that come with the Csi 2140. I think you need a Special "B" cable.
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Re: Cross Channell Phase Analysis with CSI 2140

czJKr ·
Yes there are special cables for respective channels or "fork" cables for AB and CD or an adapter with all BNC available.
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Re: Cross Channell Phase Analysis with CSI 2140

Rusty Cas ·
I bought the 4-channel adapter with mine to avoid all the cable issues, at least initially. I will be buying other cables as I sort it out. It's a little confusing. Not sure why they didn't just add 2 other connectors on the box, so you had access to all 4 channels by default. "The trend is your friend" MachineryAnalysis.org
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Re: 5MW 3phase motor, Single phase overload trip

Panta ·
If I were you I should check voltage ratio of motor in transformer mode . Here you have to be careful because if you have 6kV on stator connection it is also probably high voltage on rotor connections * I expect more than 2 kV and that information you will have on the signboard * . We used safer version respectively to give 3 x 380 V to the stator and measure current on every stator phases and rotor voltage at each resistor shortening . It can give information on whether any step you have a...
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Re: 5MW 3phase motor, Single phase overload trip

jvoitl ·
Is it possible that it is a true 3 phase overload but with the phases being 120 degrees apart your metering equipment only records the current on the phase that is highest at the time?
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Re: Cross Phase analysis issue

Hossam 2 ·
?
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Re: Cross Phase analysis issue

mirook ·
the 1X is very small now, don't care the phase then, especially the phase difference between two ends of the motor.
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Re: Cross Phase analysis issue

Hossam 2 ·
hi thank you for your reply i just figured out that the 1xts was too small but actually the phase wasnt steady and when i uncoupled the motor the vibration signature was the same and vibration values was concerning when uncoupled thats why i didnt suspect misalignment actully the cooling fan in the motor near the coupling DE was damaged and they localy manufactured a new one but the values of wasnt so high in the DE near the coupling but increased in the NDE so i will make a trial to balance it.
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Re: Phase Analysis with SKF Micolog

Reliable Analyst ·
It is very simple, simply reverse the sensors, i.e. put sensor A at location B and sensor B at location A it is as simple as 270 phase difference means a -90 phase shift, and thats what you would see if you interchage the A with B in cross channel you are interested in phase diff, it depends whether you are measuring the angle CW or CCW
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Re: Phase Analysis with SKF Micolog

ALI HAIDERR ·
Dear Reliable Analyst Thanks your reply. You means if we found phase greater than 180 degree. Reverse the location of sensors or simply minus 180 degree May I correct?
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Re: Phase Analysis with SKF Micolog

Reliable Analyst ·
yes
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Re: peak vs phase of Boiler PA fan

Walt Strong ·
1) the fan rotor needs trim balancing; either careful 1-plane or 2-plane (static-couple) 2) Horiz. motion at 4-bearings is in-phase, but motor is more flexible; possibly from higher elevation than fan bearings 3) Vert. motion is in-phase except for motor NDE If you make scaled sketch with horizontals, vertical, and horizontals by elevation you will see a pattern. Using a single channel analyzer is not as accurate as 2-channel ODS test, because amplitude and phase can change during the...
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Re: peak vs phase of Boiler PA fan

Kishore kumar ·
1x is the dominant peak in all directions and the units are peak velocity mm/sec
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Re: peak vs phase of Boiler PA fan

Walt Strong ·
Kishore, Why are you now providing spectra data that shows dominant peak is at 2xSS? Do you have the incorrect speed in the database? What is the correct speed? There are one or two peaks that are not harmonic frequencies, so they are possible bearing defect frequencies. Did you calculate bearing fault frequencies to see if there is a match? I hope you don't rely too much on the Nspectr "diagnosis"!! Walt
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Re: peak vs phase of Boiler PA fan

Walt Strong ·
"Fan is working at boiler area and it is a congested and hot area ." Is this your excuse to not do more work? So what? What is your point of asking questions about the fan? If no one is going to fix the fan, then why waste time with vibration measurements? No sympathy from me! Walt
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Re: peak vs phase of Boiler PA fan

GRB ·
First of all, while the 1x RPM (assuming it is 3000 and the database is in error) is dominant, this is not always mean it is imbalance. Misalignment, while usually showing lower harmonics of running speed, sometimes shows mostly 1x RPM. Also, there are a significant at 2x RPM peaks at M1V, M2V, M2A. Many of the phase angles are not typical of imbalance. When the transducer is moved from the horizontal to the vertical it is moved 90 degrees, but on the fan and motor drive end they are close...
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Re: peak vs phase of Boiler PA fan

GRB ·
Walt, Kishore's comment "Fan is working at boiler area and it is a congested and hot area" was answering Ralph's question "Does "hot area" mean the surrounding area temperature is hot or the fan is blowing very hot air?" I didn't see anything about not fixing the machine. Give the guy a break. Like Reply ( 0 Likes )
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Re: peak vs phase of Boiler PA fan

Shurafa ·
What are the units of the amplitudes? (mil, um, mm/sec etc)
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Re: peak vs phase of Boiler PA fan

Kishore kumar ·
peak velocity mm/sec
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Re: peak vs phase of Boiler PA fan

Kishore kumar ·
Please refer the FFT spectrum of above equipment
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Re: peak vs phase of Boiler PA fan

PKS ·
Check for the motor soft foot. Take Motor DE & NDE Hor vibration reading by loosening each motor base bolt one by one. It will come down if the soft foot problem exists in any of the motor base. Regards
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peak vs phase of Boiler PA fan

Kishore kumar ·
Dear members , please share your opinions about below attached peak vs phase readings of a Boiler PA fan ,producing high vibrations .1X is the dominant in all directions .i have taken readings by using CSI2120 single channel analyzer and with monarch phototach. Normally it is runs in hot area but the present readings are taken in shut down .please share your opinions
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Re: peak vs phase of Boiler PA fan

Walt Strong ·
This topic was double posted in Modal Analysis Section Walt
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Re: 5MW 3phase motor, Single phase overload trip

Edwin de B ·
Looks like a short circuit to ground in some place. All other problems will show an increase in current on 2 or 3 phases. Are there any parts of the power circuit that were not exchanged?
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Re: 5MW 3phase motor, Single phase overload trip

electricpete ·
That's a headscratcher all right. Are you saying that the motor has operated for 2 years normally and then the problem only showed up in the last 1-2 months? I can appreciate the logic of why a ground fault would be suspected, but…. 500A+ ground fault jumping among phases and doesn't leave any evidence (burn marks) or trip any protective relaying other than overload? That seems unlikely, although I don't have another ready explanation. If the machine were delta-wound and there were for some...
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Re: 5MW 3phase motor, Single phase overload trip

Lampard Nguyen ·
Originally Posted by Edwin de B: Looks like a short circuit to ground in some place. All other problems will show an increase in current on 2 or 3 phases. Are there any parts of the power circuit that were not exchanged? Hello Edwin, Thank you for your comment. We had replaced power cables for that motor, and also new motor was replaced. But, problem still present. I am wondering the problem come from MV Switchgear. We have not exchange MV Switchgear.
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Re: 5MW 3phase motor, Single phase overload trip

Lampard Nguyen ·
Hello Electripete, Thank you for your comment. The problem have been occuring since 2013, every 1-2 month, the problem occrued again. Sometimes high current (1000A) is at phase 1, sometimes phase 2, sometimes phase 3, It's random. New motor, new power cables, but problem still occurs. The trip is not occuring during starting, just occurs when operating. We also checked secondary circuit, no problem.
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Re: 5MW 3phase motor, Single phase overload trip

Dave Reynolds ·
I too agree this is a head scratcher.... The cables you changed, are they for the stator or rotor circuit? I am assuming you have a resistor bank that controls the speed of the motor, see attached With the amps being so high, this would typically go BOOM! I agree with epete, the meters/CT/PT that you are using need to be verified that you are truly seeing these high of current levels The rotor circuit, this could explain why the amps are random and so high. But for this to occur you would...
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