Hi All,

Can anyone help me what's wrong with our Generator by the orbit plot & spectrum details attached?

Generator is driven by Steam Turbine running at 3600 RPM. This is a newly installed equipment and on commissioning stage. My initial observation, there is a misalignment on the shaft of the Generator.

Please see the attached data.

Thank you very much.

A=mc²

Attachments

Original Post
John from PA posted:

Some machine details would be appreciated.  Size, types of bearings and arrangement, couplings, etc.  

Hi John,

Thank you for replying my query.

The size of the Generator is 105MW, bearing types is sleeve bearing 1 on top and 1 on the bottom. Couple with gear coupling.

Hope this data helps.

Vib282 posted:

1. you need to confirm whether these harmonics are true or due to shaft scratches.

2. second check the trends of the gap voltage and see if any changes are there.

3. check if any changes in the temp.

what is the type of the bearings ??

 

Hi Vib282,

On item no.1, how do I confirm that the harmonics are due to scatches?.

Item no. 2, I'll check with our instrumentation guy.

Item no. 3, based on the trend, there was a slight increase of 2 degree Celcius from the previous 71 deg. C. after 1 month of operation the temperature reading now is 73 deg. C.

The bearing type is sleeve bearing.

Thank you.

hi

you can confirm if peaks are true or fake from cost down test.

A. At slow roll check if these peaks remains there or not. if yes then they are not real. B. You can check the total energy from these peaks during cost down. if it is constant then they are not real.

Regarding the gap, if your on line system doesn't keep trends of the gap values then it is better for you in the future to collect it as a routine job by your data collector. this is a super critical parameter for a condition monitoring guy.

To confirm your doubts about misalignment, try to draw the shaft center line plot within the clearance circle at each bearing (especially across the coupling). this will show you if any abnormal SCl location is there or not. it will more clue about misalignment. 

Vib282 posted:

hi

you can confirm if peaks are true or fake from cost down test.

A. At slow roll check if these peaks remains there or not. if yes then they are not real. B. You can check the total energy from these peaks during cost down. if it is constant then they are not real.

Regarding the gap, if your on line system doesn't keep trends of the gap values then it is better for you in the future to collect it as a routine job by your data collector. this is a super critical parameter for a condition monitoring guy.

To confirm your doubts about misalignment, try to draw the shaft center line plot within the clearance circle at each bearing (especially across the coupling). this will show you if any abnormal SCl location is there or not. it will more clue about misalignment. 

Thank you Vib282, we will consider your suggestion.

maximize posted:
Vib282 posted:

hi

you can confirm if peaks are true or fake from cost down test.

A. At slow roll check if these peaks remains there or not. if yes then they are not real. B. You can check the total energy from these peaks during cost down. if it is constant then they are not real.

Regarding the gap, if your on line system doesn't keep trends of the gap values then it is better for you in the future to collect it as a routine job by your data collector. this is a super critical parameter for a condition monitoring guy.

To confirm your doubts about misalignment, try to draw the shaft center line plot within the clearance circle at each bearing (especially across the coupling). this will show you if any abnormal SCl location is there or not. it will more clue about misalignment. 

Thank you Vib282, we will consider your suggestion.

HI Vib282, just a follow-up question. Is slow roll check same as taking data during turning gear operation of the STG?

maximize posted:

Hi Rotating Guy, what specific details you are asking for?Thanks. check all the parameters that will connect to your observation, start-up plot, bode, polar, process parameters, and etc. 

 

maximize posted:

Hi All,

Can anyone help me what's wrong with our Generator by the orbit plot & spectrum details attached? More details on orbit, unfiltered, 1x filtered not only 1x. this is not a picture you just want to share, please share all the orbit, from diver to driven.

Generator is driven by Steam Turbine running at 3600 RPM. This is a newly installed equipment and on commissioning stage. My initial observation, there is a misalignment on the shaft of the Generator. your initial observation is misalignment? check the slow roll vibration to verify if there is a misalignment, i red your reply to above "HI Vib282, just a follow-up question. Is slow roll check same as taking data during turning gear operation of the STG?" as much as possible i dont want a spoonfeed things like. try to read a books to find out. anyhow, i use slowroll data from 250 to 300 rpm. with that data you can check how much the runout, i believe you are familiar with the runout. The next question you'll ask possibly, what is the limit acceptance for slow roll? the runout limit should be 25% of the OEM alert limit. use direct amplitude on slowroll. 

Please see the attached data.

Thank you very much.

 

maximize posted:
maximize posted:
Vib282 posted:

hi

you can confirm if peaks are true or fake from cost down test.

A. At slow roll check if these peaks remains there or not. if yes then they are not real. B. You can check the total energy from these peaks during cost down. if it is constant then they are not real.

Regarding the gap, if your on line system doesn't keep trends of the gap values then it is better for you in the future to collect it as a routine job by your data collector. this is a super critical parameter for a condition monitoring guy.

To confirm your doubts about misalignment, try to draw the shaft center line plot within the clearance circle at each bearing (especially across the coupling). this will show you if any abnormal SCl location is there or not. it will more clue about misalignment. 

Thank you Vib282, we will consider your suggestion.

HI Vib282, just a follow-up question. Is slow roll check same as taking data during turning gear operation of the STG?

It is possible of course. preferable from 200 to 300 rpm.

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