- An AC motor consists of a set of stationary coils, called the stator, that drive a rotating shaft, called the rotor. The AC current drives the coils, causing them to develop rotating magnetic fields. The force of the magnetic fields makes the rotor spin.
- In a brushed-type DC motor, a set of permanent magnets form the stator and a set of coils sit on the rotor. Direct current, switched between the coils, creates a repulsive force against the permanent magnets, turning the rotor.
- A DC motor's brushes are subject to friction and wear. They eventually wear out and need replacement. An AC motor operates without brushes, so its design is simpler.
- The only wear points in an AC motor are the bearings, which can last many years. Wear in a DC motor's brushes compromise long-term reliability.
- If you don't need variable speeds, AC motors are less expensive than DC for low to moderately high-power applications. At very small sizes, such as for toys, DC motors cost less.
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