Selection of copper vs. aluminum rotors for induction motors

On squirrel cage induction motors there is an important choice between utilizing a lower cost die cast or fabricated aluminum rotor versus the more expensive copper bar rotor. Utilizing the wrong rotor construction for the application can either increase costs unnecessarily or lead to catastrophic failure. This paper provides the background necessary to assist in making the proper choise. The fundamentals of rotor construction and basic information on how the induction motor works are discussed. Additionally, the effects of various materials and types of rotor construction on motor performance are analyzed.