High Pitched whine after rewind
High Pitched whine after rewind
(OP)
We recently rewound a 100HZ single phase 10 pole synchronous generator that is driven by a six pole 60HZ synchronous motor. The generator puts out the correct voltage and frequency and for all purposes, it functions as it should. The problem is that it now emits a high pitched whine that supposedly was not noticable previous to the rewind. Does anybody have any idea as to what would be the cause?





RE: High Pitched whine after rewind
Electromagnetic
Change in winding configuration (coil pitch) - can change slot harmonic vibration.
Change in winding configuration (total series turns) - affects flux levels and em vibration
Change in airgap eccentricity which can aggravate slot harmonics
Mechanical
Change in height of wedge below stator bore - might change some aerodynamic siren effects
Changes to rotor fan blades
Removal of sound insulation or change which allows more direct exit of sound to atmosphere
Other
unexplainable
There may be others, but my guess is the last one listed above.
You might try to determine the frequency to narrow down the cause.
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RE: High Pitched whine after rewind
RE: High Pitched whine after rewind
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If we learn from our mistakes I'm getting a great education!
RE: High Pitched whine after rewind
RE: High Pitched whine after rewind
RE: High Pitched whine after rewind
60hz into 6 pole motor gives 60*(2/6) = 20 rot/sec shaft output
20 rot/sec rpm shaft output into 10 pole generator gives 20*(10/2) = 100hz electrical output.
100hz voltage and fields in the generator creates 200hz vibration
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RE: High Pitched whine after rewind
If you can arrange to use a microphone and capture the data digitally for fft, that may provide a more direct info about the source of the noise.
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