The rotor vibration of two-pole induction motor with rotating magnetic fiel
d has been investigated. The vibration is measured at any relative location
of the stator and the rotor with various power supply frequencies in the e
xperiment and is analyzed in consideration of mechanical factors of the rot
or. The following conclusion is obtained through the experiment and the ana
lysis; (1) 2 omega vibration of twice the power supply frequency omega is g
enerated because of offset between the stator center and the gyrational cen
ter of the rotor. (2) Two vibrations of omega (1 - s) and omega (1 + s) whe
re s is slip ratio are generated because of the rotor unbalance or the disa
greement between the gyrational center and geometrical center of the rotor.
(3) An unstable vibration is predicted in the analysis when the power supp
ly frequency is equal to natural frequency of the rotor, however, the unsta
ble vibration was not generated in the experiment because of the damping.