Die-Cast Copper Motor Rotors: Motor Test Results, Copper Compared to Aluminum
Motor manufacturers have long realized that because the electrical conductivity of copper is nearly 60% higher than that of aluminum, substituting copper for aluminum in the squirrel cage of the induction motor would markedly increase the electrical energy efficiency of the machine. Most motors larger than about 200 kW and a few special purpose smaller motors are built with copper squirrel cage structures manufactured by a time consuming and costly fabrication process. The intricate squirrel cage of smaller motors is produced by pressure die casting aluminum. Alternative cost-effective manufacturing methods have not been devised. A major barrier to adoption of copper for the rotor has been the high cost resulting from the short die life of the ordinary die steels experienced in die casting copper with its high melting temperature (1083°C compared to 660°C for aluminum).
REVIEWS - LETTERS - REPORTS REVIEW ON EFFICIENCY IMPROVEMENT IN SQUIRREL CAGE INDUCTION MOTOR BY USING DCR TECHNOLOGY
Induction motors account for approximately 50 % of the overall electricity use in industrialized countries. In the agricultural and commercial sectors also, power consumption by ac motors is quite substantial. On an average, the energy consumed by a motor during its life cycle is 60-100 times the initial cost of the motor. Therefore efficiency of the motor is of paramount importance both during selection and operation. Even small increase in efficiency improvement can make a big difference in energy savings with accompanying decrease in air contamination. High electrical conductivity of copper in the rotor structure of a squirrel cage induction motor can achieve a reduction in overall energy losses of around 11%–19 % and a consequent increase in energy efficiency. This paper reviews the implementation of Die-Cast Copper Rotor (DCR) Motor, Efficiency improvement, Energy saving potential, adoption of DCR Technology in India and the comparisons of various efficiency standards besides the application of DCR motor in agricultural pump sets. The needs and tasks regarding the technology are also discussed. K e y w o r d s: induction motor, premium efficiency, efficiency imp rovement, die cast copper rotor, DCR technology, and efficiency standards
Squirrel Cage Induction Motors - Performance Versus Efficiency
The importance of operating motors at peak efficiency for maximum energy savings is discussed. Comparisons of standard motors and high-efficiency motors are shown. Optimum motor design requires a compromise between the various parameters. The effect of starting torque and locked rotor amperes on efficiency and power factor is demonstrated. Proper motor application can result in significant energy cost savings over the life of the motor. These savings can be greater than the initial cost of the motor.