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RANGER1
02-05-2015, 11:07 PM
For interest
Bigger high voltage motors on more applications these days are using these motors with white metal bearings.
Finding magnetic centre of motor drive shaft critical in reliable operation.
Some have a pointer arrow, some do not indicating shaft position.
If it is not checked axial load on coupling & compressor shaft may cause coupling & or compressor damage.
You may notice shaft can move in/out more than several mm.

Has anyone experienced something like this?

Josip
03-05-2015, 11:38 AM
For interest
Bigger high voltage motors on more applications these days are using these motors with white metal bearings.
Finding magnetic centre of motor drive shaft critical in reliable operation.
Some have a pointer arrow, some do not indicating shaft position.
If it is not checked axial load on coupling & compressor shaft may cause coupling & or compressor damage.
You may notice shaft can move in/out more than several mm.

Has anyone experienced something like this?

Hi, RANGER1 :)

yes it is true, my last 3,8 MW has axial movement of 12 mm and magnetic center is marked with groove on shaft and an arrow pointer on slide bearing housing... until now I saw only motors with magnetic center indication ...

I remember one discussion long time ago, but now, I am not sure about, magnetic center must be in the middle of complete movement in/out ...

I will check it like this ... first push the motor shaft to one side (in) and then start it uncoupled it will come to magnetic center and then make a mark on shaft with pencil ... then stop the motor and pull the motor shaft to another side (out) and start it again (uncoupled) it should come to the same marked position as before ... this is only my idea and maybe I am not right ...

N.B. what is written in motor operating and installation manual?

Best regards, Josip :)

RANGER1
03-05-2015, 09:28 PM
Thanks Josip,
No site manual on this on as over 30 years old, no one knows.
Most have arrow, but these do not, so will have to run up as well as get motor details.
Information on internet suggests magnet centre does not have strong force to bring it to magnetic centre, as fan on motor can influence it uncoupled.
As you say centre of bearings is a good starting point to avoid excess force on thrust faces of motor bearings.