Otherwise the behaviour of the synchronous machine would exhibit clear signs of malfunctions, I believe. There would be no reason why the amplitude of the air gap field at the base frequency would vary a lot. Why it rose may be due to a more complex mode of vibrations with multiple nodes and not only two, whose resonance frequency may have shifted close to 120 Hz. Vibration at 2 X LF (without beat like in an induction motor with broken bars) is specially present in bipolar generators (or synchronous motors) instead of an 8- poles machines like yours. Such a frequency is normally present because of the pulling force present in the air gap which is proportional to B2, B being measured by a flux probe at a given angular position in the air gap. The second post shows a strong component at 2 X LF.
0 Comments
Leave a Reply. |
AuthorWrite something about yourself. No need to be fancy, just an overview. Archives
June 2023
Categories |