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Hi analyst,

I'm a newbie in vibration domain analysis, I need your help about some vibration issue in our oil and gas field, we have an electrical motor as follow :

speed : 426 rpm

1X: 7.14 HZ

FL: 50 HZ

#POLE : 14

Ns: 428.57 rpm

OEM: ABB

MODEL : AMB 560L14A BANH

MOUNTING HORIZONTAL

DE BRG: NU 238C3 + 6038C3

NDE BRG: NU234 C3

POWER : 550KW

This motor coupled to a Vapor recovery unit, when the compressor loaded 100%, the motor tripped by NDE vibration sensor, you find in the attached picture the TWF and FFT taken from DE side (coupling side), Horiz and Vertical directions during solo run test, it seems a modulated signal (predominant frequency is 7.14 (1X)), could please give me your feedback, does any one here face this kind of issue?

Attachments

Images (4)
  • TWF DE SIDE VERTICAL
  • TWF DE SIDE HORIZONTAL
  • FFT 0-1000 HZ DE SIDE VERTICAL
  • FFT 0-1000 HZ DE SIDE HORIZONTAL
Tags: ABB, Modulated Signal, Issue, Electrical Motor, High 1X RPM, BRG, BANH, 1X predominant frequency

Replies sorted oldest to newest

@Registered Member posted:

Hi analyst,


This motor coupled to a Vapor recovery unit, when the compressor loaded 100%, the motor tripped by NDE vibration sensor,you find in the attached picture the TWF and FFT taken from DE side (coupling side), Horiz and Vertical directions during solo run test, it seems a modulated signal (predominant frequency is 7.14 (1X)), could please give me your feedback, does any one here face this kind of issue?

Abu Nafi,

You said"you find in the attached picture the TWF and FFT taken from DE side (coupling side), Horiz and Vertical directions during solo run test".

Do this mean, the motor was disconnected from the compressor?

If so, what does the data look like when connected to the compressor, (if you can capture it before the system "tripped")?

Do you have any conventional velocity and acceleration data (spectrums) and acceleration waveforms?

Looks like some of the data posted is taken in "enveloped " mode, is it?

Thanks,

Ralph

Attachments

Images (1)
  • Sidebands and carrier frequencies
RM

Hello Mr. Ralph

thank you for your prompt answer

sorry for late reply back to you, I'm in site now,

for your question,

Do this mean, the motor was disconnected from the compressor? yes, that's right

If so, what does the data look like when connected to the compressor, (if you can capture it before the system "tripped")?

I tried to collect data but unfortunately the motor had tripped, so it ran for 30 sec, I took only NDE side- find in the attached files the twfs taken during the trip.

Do you have any conventional velocity and acceleration data (spectrums) and acceleration waveforms?

Looks like some of the data posted is taken in "enveloped " mode, is it?no, the data taken are twf, and FFT spectra.

Thanks

Regards

Abu Nafi

Attachments

Images (2)
  • TWF During Trip NDE side: TWF during Trip NDE Side
  • zoom P2 horizontal
RM

Thanks for the reply Abu Nafi.

I am at a lose as to what the units of measurement you are using. I have never seen this type units

Can you convert the WF and Spectrum data to: velocity or acceleration in the spectrum and acceleration RMS in the waveforms?

I am also wondering why there are so many 1x (7.14 Hz) peaks in your spectrum.

Please see the attached image and the questions attached to it.

Sorry for so many questions and so few answers to the possible problem .

Thanks and Have a Safe and Great Day,

Ralph

Attachments

Images (1)
  • 2nd question on data
RM
@Registered Member posted:

Thanks for the reply Abu Nafi.

I am at a lose as to what the units of measurement you are using. I have never seen this type units

Can you convert the WF and Spectrum data to: velocity or acceleration in the spectrum and acceleration RMS in the waveforms?

I am also wondering why there are so many 1x (7.14 Hz) peaks in your spectrum.

Please see the attached image and the questions attached to it.

Sorry for so many questions and so few answers to the possible problem .

Thanks and Have a Safe and Great Day,

Ralph

Mr. Ralph

Can you convert the WF and Spectrum data to: velocity or acceleration in the spectrum and acceleration RMS in the waveforms?

I did it, could you please have a glance on the attached files with Zoom's pictures

I am also wondering why there are so many 1x (7.14 Hz) peaks in your spectrum. I also do

Please see the attached image and the questions attached to it.

yes, our FL here is 50 Hz

Sorry for so many questions and so few answers to the possible problem .

you are welcome any time, don't hesitate to ask more

best regards

Abu Nafi

Attachments

Images (6)
  • Vertical P1 (Acceleration) 30 sec before Trip: Horizontal P1 (Acceleration) 30 Sec before Trip
  • Horizontal P2 (Acceleration)
  • Vertical, P2 FFT (Velocity)
  • cluster Zoom 01
  • Cluster Zoom 02
  • Cluster Zoom 03
RM
@Registered Member posted:

no, it's an induction motor, the Name plate RPM is : 425 RPM, but the real RPM is: 428.4 rpm, so there is a slip of 3.4 RPM.

Thanks

Abu Nafi

7.14 Hz x 60Hz = 428.4 RPM.

Is this 428.4 RPM, the uncoupled (no load) speed.

If so, what is the rpm when coupled and loaded, the tag speed of, 425? And this is the 3.4 "slip" when fully loaded?



Thanks,

Ralph

RM
@Registered Member posted:

7.14 Hz x 60Hz = 428.4 RPM.

Is this 428.4 RPM, the uncoupled (no load) speed.

If so, what is the rpm when coupled and loaded, the tag speed of, 425? And this is the 3.4 "slip" when fully loaded?



Thanks,

Ralph

Ralph,

absolutely, 428.4 RPM is no load speed.

the Tag speed is 425 RPM, 3.4"slip" when no loading, when fully loaded the speed will be 425.4 RPM(7.09 HZ), So, the slip will be .4

regards

Abu Nafi

RM
@Registered Member posted:

Ralph,

absolutely, 428.4 RPM is no load speed.

the Tag speed is 425 RPM, 3.4"slip" when no loading, when fully loaded the speed will be 425.4 RPM(7.09 HZ), So, the slip will be .4

regards

Abu Nafi

Abu Nafi,

Are there any +/- 0.7 Hz sidebands off of any carrier frequencies in the spectrum or waveform?

Does your analyzer have the ability to capture a spectrum and waveform in envelope mode (with acceleration Gs units) with a High Pass Filter of 500 and/or 1000 Hz with 6400 lines or greater lines of?

Thanks,

Ralph

RM
@Registered Member posted:

Abu Nafi,

Are there any +/- 0.7 Hz sidebands off of any carrier frequencies in the spectrum or waveform?

Does your analyzer have the ability to capture a spectrum and waveform in envelope mode (with acceleration Gs units) with a High Pass Filter of 500 and/or 1000 Hz with 6400 lines or greater lines of?

Thanks,

Ralph

Hi Ralph,

I hope you are doing well,

Are there any +/- 0.7 Hz sidebands off of any carrier frequencies in the spectrum or waveform?

I didn't find such sidebands

Does your analyzer have the ability to capture a spectrum and waveform in envelope mode (with acceleration Gs units) with a High Pass Filter of 500 and/or 1000 Hz with 6400 lines or greater lines of?

find in the attached file

Thanks

Abu Nafi

Attachments

Images (2)
  • VERTICAL P02
  • VERTICAL P02: ENEVELOPE High res 12800
RM
Last edited by Registered Member
@Registered Member posted:

Hi Ralph,

I hope you are doing well,

Are there any +/- 0.7 Hz sidebands off of any carrier frequencies in the spectrum or waveform?

I didn't find such sidebands

Does your analyzer have the ability to capture a spectrum and waveform in envelope mode (with acceleration Gs units) with a High Pass Filter of 500 and/or 1000 Hz with 6400 lines or greater lines of?

find in the attached file

Thanks

Abu Nafi

Hi Ralph,

I noted that the difference between the carrier frequencies is 7.1(refers to the speed), also it has a sidebands +/-1.2

find the attached file.

Thanks

Abu Nafi

Attachments

Images (1)
  • Env.1kHz High res 12800
RM
@Registered Member posted:

Thanks for the reply.

Can you confirm the sidebands I have marked in the images as being, slip and 14 poles, related??

See the attached images taken from the image you attached to your last reply.

Thanks,

Ralph

Hi, Ralph

let me say thank you for this useful change

Can you confirm the sidebands I have marked in the images as being, slip and 14 poles, related??

I still look for the relation, but seems no relation, in the meanwhile I confirm that the Fs .79

Actually, there is a question had slipped my mind days ago, can we distinguish the type of loading that the bearing exposed to (radial or axial?) from the spectrum? if so, how?

Thank you again

Abu Nafi

RM
@Registered Member posted:

Hi, Ralph

let me say thank you for this useful change. You are welcome.

Can you confirm the sidebands I have marked in the images as being, slip and 14 poles, related??

I still look for the relation, but seems no relation, in the meanwhile I confirm that the Fs .79 What does "Fs .79" Refer to?

Actually, there is a question had slipped my mind days ago, can we distinguish the type of loading that the bearing exposed to (radial or axial?) from the spectrum? if so, how? I am not sure about the "load" from the "spectrum".

I just noticed that some of the spectrums you gave us are "envelope" type with a 5K- 10K Hp Pass Filter. Thanks.

It is strange that in the Enveloped data, that you show us, extends the harmonics of 1X so far out into the higher frequencies area.

Was this data taken with a load or solo on the motor?

As I said earlier, the 1.19 Hz sidebands (if I am correct in the numbers) on the 1X harmonics, divided by 14 poles, gives us 0.085 Hz times 60Hz (for rpms) and seems to give us a 5.1 rpm slip frequency. If this is all true, it sound as though there might be a rotor or pole problem in the motor.

One more question, is the motor currently running and driving the compressor at a low load or do you still have it (machine) sitting idle, off-line?

Thanks,

Ralph



Thank you again

Abu Nafi

RM
@Registered Member posted:

I still look for the relation, but seems no relation, in the meanwhile I confirm that the Fs .79 What does "Fs .79" Refer to?

I think, .79 Hz refers to Slip frequency, Speed 428.4 and we have Speed in the plate 425 RPM So, we have difference of 3.4 RPM, Fs=Slip#No.pole/60 = .79 HZ

Actually, there is a question had slipped my mind days ago, can we distinguish the type of loading that the bearing exposed to (radial or axial?) from the spectrum? if so, how? I am not sure about the "load" from the "spectrum".

I just noticed that some of the spectrums you gave us are "envelope" type with a 5K- 10K Hp Pass Filter. Thanks.

It is strange that in the Enveloped data, that you show us, extends the harmonics of 1X so far out into the higher frequencies area.

Was this data taken with a load or solo on the motor? it was taken with solo test.

As I said earlier, the 1.19 Hz sidebands (if I am correct in the numbers) on the 1X harmonics, divided by 14 poles, gives us 0.085 Hz times 60Hz (for rpms) and seems to give us a 5.1 rpm slip frequency. If this is all true, it sound as though there might be a rotor or pole problem in the motor.

One more question, is the motor currently running and driving the compressor at a low load or do you still have it (machine) sitting idle, off-line? yes,the motor driving the compressor and running now with fully loading (100%), the vibration seismic level seems steady about 1.24 mm/s RMS, the signal shows also High Kurtosis (refers to impulsional bearing shocks). the kurtosis normally value is 3, but the attached two signal showed a high value.

Thanks,

Ralph

Attachments

Images (2)
  • RV P2 with fully loading before greasing
  • RV P2 with fully loading after greasing
RM
@Registered Member posted:

I still look for the relation, but seems no relation, in the meanwhile I confirm that the Fs .79 What does "Fs .79" Refer to?

I think, .79 Hz refers to Slip frequency, Speed 428.4 and we have Speed in the plate 425 RPM So, we have difference of 3.4 RPM, Fs=Slip#No.pole/60 = .79 HZ

Actually, there is a question had slipped my mind days ago, can we distinguish the type of loading that the bearing exposed to (radial or axial?) from the spectrum? if so, how? I am not sure about the "load" from the "spectrum".

I just noticed that some of the spectrums you gave us are "envelope" type with a 5K- 10K Hp Pass Filter. Thanks.

It is strange that in the Enveloped data, that you show us, extends the harmonics of 1X so far out into the higher frequencies area.

Was this data taken with a load or solo on the motor? it was taken with solo test.

As I said earlier, the 1.19 Hz sidebands (if I am correct in the numbers) on the 1X harmonics, divided by 14 poles, gives us 0.085 Hz times 60Hz (for rpms) and seems to give us a 5.1 rpm slip frequency. If this is all true, it sound as though there might be a rotor or pole problem in the motor.

One more question, is the motor currently running and driving the compressor at a low load or do you still have it (machine) sitting idle, off-line? yes,the motor driving the compressor and running now with fully loading (100%), the vibration seismic level seems steady about 1.24 mm/s RMS, the signal shows also High Kurtosis (refers to impulsional bearing shocks). the kurtosis normally value is 3, but the attached two signal showed a high value.

Thanks,

Ralph

Abu Nafi,

Thanks for the reply.

Sounds like maybe, if it running good now, it is best to leave it alone for now, huh?

Thanks,

Ralph

RM

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