Hello to everyone,
have you some explanations about the phenomena in the subject?
I'm sure about the nature of the 300 Hz, is electric, but I don't have any idea about the origin.
The motor is AC, is about 100 kW, and have 2 poles (about 3000 rpm), on the plant there aren't other motor with this phenomena and there aren't DC motor. The vibration level is quite low, about 4 mm/s rms (0,16 inch/s rms)
Thanks
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VIBA posted:
I'm sure about the nature of the 300 Hz, is electric, but I don't have any idea about the origin.
What have you done that makes you sure it is electrical? This isn't a VFD drive is it?
Since you have 50Hz grid, 3 phase rectifying give 300Hz that is normal in DC drives, furnaces and old or less functional VFD. So if it is 300.00 Hz, go and find a thing with rectifiers that leak back in to the grid, likely on the same transformer as where you find it. Olov
John from PA posted:VIBA posted:
I'm sure about the nature of the 300 Hz, is electric, but I don't have any idea about the origin.
What have you done that makes you sure it is electrical? This isn't a VFD drive is it?
I'm sure because in asynchronous motor without VFD, if you change the load you can change the speed, and I 've done this test.
With a not significant change in speed (20 rpm / 0.33 Hz) I didn't see any change in 300 Hz (300 Hz is about 6x of motor speed so If was a multiple or a bearing I've to see move about 2 Hz).
There is another test but was impossible to perform.
Hi Everyone,
I've seen same situation seeing 300 Hz in the spectrum on an AC motor with soft starter. I'm suspecting it is from SCR Firing rate but would it be possible to have SCR on an AC motor?
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