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jerardo martinez

Posts: 4
Reply with quote  #1 

Hi guys,  i,ve a problem with 4Poles Generator 8Mgw in Turbocompressor Solar Mars (Turbine-gearBox-Generator),   High Level Vibration Axial NDE 2x (2x1800=3600cpm), 0.26 in/seg(pk).   

A) The first test were with change Load level (decrement from 8Mgw to 0.5 Mgw), 

Decrease  in amplitude is observed due to the change load level:

8Mgw, Level vibration @2x= 0.26 in/seg(pk),  the last level (0.5Mgw)= 0.08 in/seg(pk).   View Anex.

Phases: NDE Axial

1x= In fase (4 axial points, 12,3,6,9)

2x= OutFase 90degres (12,3,6,9)

view anex PCM-1...docx

Observed sidebands 525cpm in 1x and 2x

B) Last test  
In RunUp, at the moment of feeding voltage (12kv) break inside, 
the vibration at twice the turn (2x) appears in a high way.

Also a resonant zone is observed at approximately 1500cpm, 
this excites the rotation frequency (1x). See Annex 2) .- HsXXXX .... docx


Attached Files
docx PCM-1.docx (209.65 KB, 16 views)
docx HsXXXX PCM0918 AVGenMARS.docx (2.02 MB, 14 views)


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Sr. Member
Posts: 106
Reply with quote  #2 
this problem in your machine is new or you had it before?

As with electric-motor rotors, generator rotors always seek the magnetic center of their
casings. As a result, they tend to thrust in the axial direction. In almost all cases, this
axial movement, or endplay, generates a vibration profile that includes the fundamental
(1X), second (2X), and third (3X) harmonic of running speed. Key monitoring parameters
for generators include bearings, casing and shaft, line frequency, and running
speed. Normally this pattern increases his leves with the load.

The third (3X) harmonic of running speed is a critical monitoring parameter. Most, if
not all, generators tend to move in the axial plane as part of their normal dynamics.
Increases in axial movement, which appear in the third harmonic, are early indicators
of problems.


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Sr. Member
Posts: 106
Reply with quote  #3 
¿este problema en su máquina es nuevo o lo tuvo antes?

Al igual que con los rotores de motores eléctricos, los rotores de los generadores siempre buscan el centro magnético de sus
envolturas. Como resultado, tienden a empujar en la dirección axial. En casi todos los casos, este
movimiento axial o juego axial genera un perfil de vibración que incluye el armónico fundamental
(1X), el segundo (2X) y el tercero (3X) de la velocidad de carrera. Los parámetros clave de monitoreo
para los generadores incluyen rodamientos, carcasa y eje, frecuencia de línea y
velocidad de funcionamiento . Normalmente este patrón aumenta sus niveles con la carga.

El tercer armónico (3X) de la velocidad de funcionamiento es un parámetro de monitoreo crítico. La mayoría, si
no todos, los generadores tienden a moverse en el plano axial como parte de su dinámica normal.
Los aumentos en el movimiento axial, que aparecen en el tercer armónico, son indicadores tempranos
de problemas.
Sidebands to 525 cpm... need more information about you equipment: exciter frecuency, line frecuency (50 Hz or 60 Hz)...etc. but it may be a frecuency modulation.... amplitude leves for sidebands increase with the load???

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