The comparison of the 100 Hz component between the vibrations in the radial and axial directions for all of the locations under the rated load is shown in Fig. 12. It is interesting to note that the radial vibrations from the selected locations are relatively equal. Although the electromagnetic force in the radial direction is larger than that in the axial direction for most coils, the vibrations in the axial direction are more significant. This is one of the reasons that only the axial vibrations are considered in this paper