Copper has high electrical conductivity then aluminum so this feature it ideally suitable for rotor bars and end rings in induction motors. Usually aluminum was used for manufacturing of rotor bars as they have low melting temperature. But now techniques has been developed to develop rotors with die cast copper. Copper has melting temperature then aluminum so it difficult to manufacture.
Due to high conductivity and lower resistive losses so rotors with copper make the motor more energy efficient than aluminum.
There are following advantages of using copper die cast rotors instead of aluminum rotors:-
11. Copper rotors will leads to reduced size of motor for same efficient motors using aluminum rotors. For same efficient motors as that of copper rotor length of aluminum rotor needed to be increased to about 15-20% . Increase in rotor length increase the cost of many of the other components used in manufacturing the motor.
As we know that stator and rotor in motors contain stampings and stacks of lamination steel. Now when we Increase the length of the rotor it will leads to increase in the amount of electrical grade lamination steel that is required, and the number of stampings.
In stators there is winding of copper. Now when there is increase in length of aluminum rotor the length of the stator increase which directly impacts the copper wire content and processing time requirements.
This will leads to heavier motor. Which means bearings of higher load bearing capacity needed to be installed. Thus we see that copper rotors initial cost is offset by other changes in motors.
22. Copper rotors will leads to motor power savings and enhanced efficiency motors
Motors account for more than 70% of the electrical energy use in industrial sector worldwide. Motors with copper rotors will leads to Incremental improvements to electric motor efficiency means more power savings.
33. Copper rotors also provide better global environmental benefits as copper rotors consume less power which will leads to lower carbon emissions. With growing environmental consciousness of businesses, governments, and consumers; and high global energy costs and carbon taxes drive the need to continuously seek more energy efficient materials and processes.
Although there is higher cost of manufacturing the copper rotors but payback period for using in industrial motors is less than 1 years. Copper rotors enables to achieve up to 2.5% efficiency gains in current aluminum based products without increasing the size of the motor.