FAVI S. A., a die-caster producing copper rotors in France, reports that motors utilizing copper rotors run at significantly lower temperatures than similar motors with aluminum rotors. The FAVI data indicate that copper conductor bars decrease I2R losses by 40%, leading to significantly lower joule heating. FAVI's measurements for a 7 kW motor showed that the rotor will operate 15oC cooler, and the stator 5°C cooler.
Running the motor cooler is known to extend motor life. An empirical law suggests that a 10oC reduction in operating temperature will extend motor life by a factor of two.
Information on the FAVI report can be found on data sheet number 03.
Cooler operation results in longer motor life.