Shaft diameter

The shaft diameter in Emetor is the diameter of the hole in the iron laminations that contains the shaft.

For most motors, the diameter of the mechanical shaft and the diamter of the hole in the iron laminations that contains the shaft is the same. This is due to the fact that the shaft and the iron laminations are glued, or heat and freeze shrinked together. However, looking at the 30-poles hydro generator in Fig. 1, you will notice that the diameter of the hole in the iron laminations that contains the shaft is much larger than the actual diameter of the mechanical shaft.

The shaft diameter is defined as the diameter of the hole in the iron laminations that contains the shaft, as indicated with the red arrow in Fig. 1 (and not as the actual diameter of the mechanical shaft, which can be much smaller). In Emetor, therefore, we refer to the shaft as the magnetically non active part in the middle of the machine rather than to its mechanical function.

Fig. 1 Illustration of shaft diameter as defined in Emetor of a 30-poles hydro generator.

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