Is it possible vibration may appear on line frequency(50 HZ)?and what is the reason of this?
We experienced a high vibration on motor with exciter even RPM 69 during startup upto 500 microns.
Dominant peaks are 50Hz and 100 Hz.
Then electrical department replaced some diaodes in exciter of the motor,now motor is running ok.
But i want to know that why dominant vibration was on 50HZ(line frequency)?even motor speed is 1500 RPM,