Re: Copper Rotor
Implications? Copper for the rotor bars will have lower losses (and silver lower still) but aluminum is infinitely more popular simply because it is easier to cast the bars in place with it. Copper does not form good castings and any alloying to improve the casting ability (e.g. - the bronzes and brasses) results in a much higher bulk resistivity (called ρ, or lower case rho).
The induction motor has been around for more than 100 years - there's not much new going on inside of one these days.