Quantifying excessive mechanical vibration in a 1.5hp 3450 rpm motor?
Quantifying excessive mechanical vibration in a 1.5hp 3450 rpm motor?
(OP)
I have spoken to several local electrical motor service centers, but none have been able to indicate an actual method of simply quantifying vibration in small motors (with the viewpoint of establishing if a given motor is unacceptably unbalanced).
In my particular case, a brand new 1.5hp 2 pole 3450 rpm motor (for driving woodworking machinery) appears to vibrate (under no load) much more than any similar motor I have ever encountered. A second new motor vibrates similar to the first, thus I am inclined to believe that the problem lies in all thier units. The problem appears to be a mechanical imbalance since the vibration diminishes slowly as motor winds down.
I would assume that an unbalanced motor under no load conditions, and suitably mounted would oscillate by a quantifiable displacement, possibly as measured by a dial indicator against the housing. Is there any such or similar method by which I can gage this vibration?
I wish to press the manufacturer for some sort of further solution but I would prefere to have some kind of hard data (rather than a vague complaint about vibration) to back up my claim. Any replies would be greatly appreciated.
In my particular case, a brand new 1.5hp 2 pole 3450 rpm motor (for driving woodworking machinery) appears to vibrate (under no load) much more than any similar motor I have ever encountered. A second new motor vibrates similar to the first, thus I am inclined to believe that the problem lies in all thier units. The problem appears to be a mechanical imbalance since the vibration diminishes slowly as motor winds down.
I would assume that an unbalanced motor under no load conditions, and suitably mounted would oscillate by a quantifiable displacement, possibly as measured by a dial indicator against the housing. Is there any such or similar method by which I can gage this vibration?
I wish to press the manufacturer for some sort of further solution but I would prefere to have some kind of hard data (rather than a vague complaint about vibration) to back up my claim. Any replies would be greatly appreciated.






RE: Quantifying excessive mechanical vibration in a 1.5hp 3450 rpm motor?
I'd start by taping a half key in the naked shaft and run it to evaluate the balance.
RE: Quantifying excessive mechanical vibration in a 1.5hp 3450 rpm motor?
Balance is checked with the rotor removed on a balance machine. There are ISO standards addressing balance grades.
Vibration can be checked with the machine assembled and running. NEMA MG-1 calls out a limit on the order of 0.12 ips for rigidly mounted machines (new). About 0.15 ips for resiliently mounted. Higher limits generally apply to in service machine, and ISO addresses these as well. If you consider the level to be unacceptable, checking the frequency of vibration (among other things0 will help you beging to narrow down the cause.
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RE: Quantifying excessive mechanical vibration in a 1.5hp 3450 rpm motor?
I did attempt to find a clearer description of what NEMA mg-1 limit of 0.12 ips means but was unsuccessful. The information appeared available but at a significant and prohibitive cost for a one time purpose. Electricpete, if you have a moment, and if you can, could you please define .12 ips, or indicate anything else that might assist? Thank you.
RE: Quantifying excessive mechanical vibration in a 1.5hp 3450 rpm motor?
I'm not sure what you mean. ips stands for inches per second (overall peak-0 unfiltered). It must be measured with a vibration monitoring instrument and anyone qualified to use the instrument will be familiar with the units and setup. I don't see any other way to quantify vibration.
I'm not sure if I have answered your question.
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RE: Quantifying excessive mechanical vibration in a 1.5hp 3450 rpm motor?