SOME COMMENTARY ON THE CHOICE OF ROTOR BAR MATERIAL FOR INDUCTION-MOTORS

Almost any metal can be used ir the design of the squirrel cage of an induction machine. Obviously lead is not used because of its low melti ng point and magnesium because of its low flash point. Others are reje cted because of the cost, lack of strength, resistance, thermal conduc tivity, or manufacturability including ease of joining. Basically, the choice falls to two materials, aluminum and copper and their alloys. For lowest cost of manufacture, especially for mass production, alumin um surpasses copper.; In order to determine which of the two materials is the best takes the combined skills of an electrical, a mechanical and a metallurgical engineer. This paper discusses some of the conside rations in the choice of rotor bar material.