Reductions in weight and manufacturing costs have turned out to be supplementary benefits of optimization for the copper rotor.

Material mass comparison of motors optimized for same EPACT electrical efficiency

Example 1. Power = 5.5 kW      efficiency = 89.6%

Rotor conductor	Al	Cu
Stator + rotor steel final kg / starting kg	34.5 / 45.9	27 / 35.9
Stator winding kg	7.3	4.4
Rotor cage kg	2.0	3.6
Total copper kg	7.3	8.0

7.5 / 10 kg less steel      0.7 kg more copper


Example 2. Power = 11 kW efficiency = 91.1%

Rotor conductor	Al	Cu
Stator + rotor steel final kg / starting kg	54.5 / 72.7	43 / 57.3
Stator winding kg	10.2	8.7
Rotor cage kg	3.0	5.9
Total copper kg	10.2	14.6

11.5 / 15 kg less steel     4.4 kg more copper

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