Assessment of induction motor cage fatigue life

The induction motor is widely recognized as being inherently the most reliable motor for industrial drives. Attention to the detailed design of the rotor cage winding is necessary to realise the full potential for high reliability. Transient and steady state conditions must be considered with regard to the combined thermal and rotational stresses and their affect on the cage life. The author describes those mechanisms which lead to cage failure due to fatigue. The author describes how the stress levels may be calculated and how this in turn can be used to assess the fatigue life of a given design