Traditional induction motors need to draw current from the power grid to generate a magnetic field. This current is called "excitation current" and it consumes electrical energy without doing useful work. In contrast, a permanent magnet motor has its own built-in permanent magnets on the rotor, so the magnetic field is provided by the magnets and no excitation current is required. As a result, the power factor is extremely high (close to 1), and copper losses are greatly reduced. Moreover, in actual operation, permanent magnet motors maintain high efficiency even under light loads, while traditional motors suffer a sharp drop in efficiency at light loads. This is the fundamental reason why permanent magnet motors generally achieve comprehensive energy savings of 10%–30%.