IE3 motors ensure 10% efficiency increase says NORD

the starting torque, The torque curve in the operating region is considerably steeper, while the breakdown torque is attained with a lower slip.

In addition, the starting torque, which is proportional to the rotor losses, is significantly lower. Unlike aluminum motors, IE3 motors with a copper rotor do not require an increased amount of iron or need merely a moderate increase.

However, NORD says as well as the choice of alternative materials such as copper, other measures can also be taken. These include the use of sheet lamination material with lower specific core losses, larger conductor cross-sections in the windings, flux-optimised windings and smaller winding heads.Further increases in efficiency can also be achieved with permanent magnet motors and with frequency tihign inverter operation (synchronous motor principle).