Representation of rotor spiders and axial ventilation ducts in reduced finite-element models for cage rotors

The authors examine a number of alternative schemes for incorporating rotor asymmetries in reduced finite-element models of cage motor rotors. The asymmetries examined arise as a result of the use of spider arms to support the rotor core on the shaft or axial ventilation holes in the rotor core back. Calculated results show that both features can be allowed for with adequate accuracy in a model that spans a single-slot pitch.