Axial Vibration in Motor

Dear All;
In Frictional bearing ( Plain Bearing) supported High Tension Motors there is a possiblity to determine, set the centring of the rotor, which facilitates in Magnetic centring of the rotor at Running condition.

Question 1?
In case of Antifriction bearings supported HT Motors, Whether it is applicable ? If so How to determine the magnetic Centre of the rotor? whether it affects the life of the thrust bearing ( Normally Deep groove Brg) used in this application.

Question 2 ?
Whether a improperly centred rotor will induce high axial Vibration ?

Question 3?
Sources of axial vibration in motor ?
Original Post
quote:
Originally posted by Prabhu:
Dear All;
In Frictional bearing ( Plain Bearing) supported High Tension Motors there is a possiblity to determine, set the centring of the rotor, which facilitates in Magnetic centring of the rotor at Running condition.

Question 1?
In case of Antifriction bearings supported HT Motors, Whether it is applicable ? If so How to determine the magnetic Centre of the rotor? whether it affects the life of the thrust bearing ( Normally Deep groove Brg) used in this application.

Question 2 ?
Whether a improperly centred rotor will induce high axial Vibration ?
Hi Prabhu,

To have some understanding of the Ht motor,what're the machine train configuration as fundamental?With the configuration being noteworthy, then solution will be much easier.There are few methodological procedures to be follow such as : Magnetic flux, motor current, bearing signatures,ARMD and lastly phase analysis.
Prabhu,
Q1:
Not applicable. The axial magnetic centre is determined by overall dimensions and associated machining clearances of stator and rotor parts and can not be manipulated externally.
In worst case, machining clearances may add up to one side and create axial magnetic force however should normally not pose a problem to a thrust bearing. Temperature okay, then axial force can not be excessive.
Q2:
Axial magnetic force has frequency 0 hz so no vibrations are induced.
Regards,
Arie Mol, NL
Hi Prabu & all,

One of the best and powerful diagnostic tools is to carry out ARMD.You dont need to collect data on the vibration however wahat you need are: Machine actual characteristics,bearing type,machine dimension and lastly would be start up time.

Look them easy,computing the software is not that straight forward then.



Good day!


Regards

Bobadia
No radial centering is required. Axial centering should be there during running condition. In HT motors with journal bearings, you will find a pointer near the motor inboard bearing which should be matched with a groove on the shaft during coupling with the driven equipment. If you do so, during running, motor will automatically get magnetic center. Normally, such motor have high axial float. so, during coupling this should be taken care of otherwise the motor rotor may move continuously back and forth during normal running.
I want to know more about the motor rotor moving continuously back and forth during normal running.
If you can help it will be nice...
We are having a motor which is not moving in uncoupled condition. But in coupled condition it moves forth and back while there is no movement in coupled fan rotor. We believe we have placed motor in magnetic centre as it does not move in uncoupled condition.

quote:
Originally posted by AKHTAR:
No radial centering is required. Axial centering should be there during running condition. In HT motors with journal bearings, you will find a pointer near the motor inboard bearing which should be matched with a groove on the shaft during coupling with the driven equipment. If you do so, during running, motor will automatically get magnetic center. Normally, such motor have high axial float. so, during coupling this should be taken care of otherwise the motor rotor may move continuously back and forth during normal running.

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