Torsional mode frequency and supply vibration
Torsional mode frequency and supply vibration
(OP)
Hello,
I am making a design of a blower. The impeller is rigidly coupled to the motor. Shall I design the system torsional natural frequencies to be above motor supply frequency (60Hz)? What about 2 x supply(120Hz) ?
Many thanks!
-S
I am making a design of a blower. The impeller is rigidly coupled to the motor. Shall I design the system torsional natural frequencies to be above motor supply frequency (60Hz)? What about 2 x supply(120Hz) ?
Many thanks!
-S





RE: Torsional mode frequency and supply vibration
120hz is an important torsional exciting frerquency since it exists for single phase motors or unbalanced 3-phase motors.
I don't think 60hz is particular important. During DOL start, there is torque oscillation at a frequency (1-s)*60hz... but should not remain at 60hz for long.
I would think running speed and 2x running speed may be good to avoid. Possibly number of blades times running speed also.
Vfd could make life more complicated.
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(2B)+(2B)' ?
RE: Torsional mode frequency and supply vibration
Actually, the case here is inverter driven 3-phase motor, so life is complicated :) Sorry not mention that in my 1st post.
But anyway, you think that 1x supply is not that significant excitation as 2x supply? Resonance would be there but with a smaller amplitude?