Pump Bearing - Drive End
Pump Bearing - Drive End
(OP)
Pump drive end bearing showed momentary vibration increasing abnormal sound after completion of test and commissioning of the new VFD for the 1000 Hp motor driving this 13,900 iGPM pump.
I'm new to this group, your opinions would help me a lot. My question is : Do frequent starts and stops during the test and commissioning of the new VFD has triggered this bearing abnormality?
many thanks..
neilsk
I'm new to this group, your opinions would help me a lot. My question is : Do frequent starts and stops during the test and commissioning of the new VFD has triggered this bearing abnormality?
many thanks..
neilsk





RE: Pump Bearing - Drive End
If you do have a bearing problem, I would be looking for some mechanical abnormality, ie, lack of lubrication, poorly aligned pump / motor, poor assembly technique, faulty bearing etc.
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: Pump Bearing - Drive End
RE: Pump Bearing - Drive End
It must be your browser as I can read all of Artisi's reply.
I've put in extra space on the right so hopefully you can read this.
He asked why you felt there was a problem with the bearings?
He also asked why you thought frequent starts or stops would cause bearing problems
if the bearings were correctly sized, installed and lubricated?
He then stated that if you took the pump apart and found that you had bearing problems, the
problems probably were due to some mechanical abnormality such as lack of lubrication, poorly
aligned pump or motor, poor assembly technique, or a faulty bearing.
Artisi has tremendous experience in this field, based on his posts in this forum.
I'd recommend paying attention to his advice.
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RE: Pump Bearing - Drive End
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Pump Bearing - Drive End
<a href="http://www.eng-tips.com/threadminder.cfm?pid=407">Pump engineering Forum at Eng-Tips</a>
The pump was not taken out. A new VFD drive was installed for the motor but before the new VFD was installed this pump was normally running with the old VFD in it an had no issues on pump drive-end bearing.
RE: Pump Bearing - Drive End
The pump and motor with VFD were in late 1990's. We replaced the VFD with a brand new one of the same rating.The coupling was not changed but there was alignment check as part of routine maintenance prior to the test and commissioning.
thanks..
RE: Pump Bearing - Drive End
RE: Pump Bearing - Drive End
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: Pump Bearing - Drive End
I know that motor manufacturers typically prefer one VFD mfg over another for this very reason. Im not an electrical expert (but i would ask one) - ive seen dV/dt filters used to filter the "harmful" electrical harmonics.
Another solution (if the pump can handle it), run the motor full speed and see if there is still a noise/vibration issue. That would isolate whether it is caused by the VFD or motor.
RE: Pump Bearing - Drive End
Thanks everyone who had shared their expertise, this is a good place of continuous learning!
We already had replaced the bearing including the NDE. Now, some expert said recheck the pump-motor alignment after it has run for a couple of hours or in hot condition, while others said if there were no noticeable abnormal noise and rise in bearings temperature there is no problem in the bearing and the alignment.
My new question is how many run-time should be good to recheck the alignment after recoupling with new bearings?
Many thanks.
RE: Pump Bearing - Drive End
It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)
RE: Pump Bearing - Drive End
It could just be coincidence so monitor carefully for the next 100 hours run time and then monitor at increased intervals as time goes on. Assume you have vibration monitors so take records of readings to see if they stay stay or increase over time.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way