ABSTRACT
The copper rotor induction motor (CURIM) was recently introduced because it has lower rotor fusion losses than the aluminum rotor (ALRIM). Furthermore, with CURIM, it is easier to reach IE4 and IE5 efficiency levels. The CURIM is advantageous for compact motors, escalators, and electric vehicle applications. However, CURIMs present slip, power factor, temperature increase, and torque decrease problems that must be analyzed. This study compared the economic feasibility of using CURIM with ALRIM by applying discount techniques. A case study was carried out in a sugar company with a cyclical operation, where 5.5 kW motors will be installed in the intermediate conductors of the mill's feeders. The facility works three shifts between 3 and 6 months. The cost increase (CI) of CURIM over ALRIM was between 1.1 and 1.5 times. With 3,600 h/year and 4,000 h/year of operation, the CI greater than 10%, it was found that the payback is more than four years, and the net present value (NPV) grows linearly.
Keywords:
Copper rotor induction motor, Economic feasibility, Electric motors, Energy efficiency, High-efficiency motors
This is an open access article under the CC BY-SA license.
1. INTRODUCTION
A significant reduction in rotor losses is achieved using copperrotor induction motors (CURIM)
instead of aluminum rotor induction motors (ALRIM). This is mainly because the electrical conductivity of
copper is approximately 170% that of aluminum; therefore, the total machine losses also decrease. In a
medium power induction motor, from 15% to 25% of the total losses, the efficiency increases from 2% to 5% [1], [2]. However, problems regarding the copper casting process have had to be solved first due to the high melting temperature of copper compared to aluminum (1,083 C for copper compared to 660C for aluminum). The fundamental difficulties that appeared were shortened life of the die, oxidation in the casting process of pure copper, and porosity distributed in the molten copper [2].
As the electric power cost grew, awareness grew that the motor life cycle cost is essential, and consumers realized the convenience of paying a higher initial cost for more efficient motors [3].
Additionally, a driving factor has been government regulations and incentives. So, many companies and associations have worked to eliminate the drawbacks of copper casting and have developed die materials and casting processes forrotor manufacturing, which have made mass production possible and economical [1], [2], [4].
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