What is the most common type of rotor used in a 3-phase AC motor?

The squirrel cage rotor is the most commonly used type in 3-phase AC motors mainly due to its robust design, reliability, and relatively low cost. This rotor type consists of laminated iron cores with conductive bars placed in a manner resembling a cage, which are shorted at both ends. These characteristics allow for efficient operation and less maintenance compared to other rotor types.

One key advantage of the squirrel cage rotor is its simple construction, which reduces the likelihood of mechanical failure and the need for complex maintenance. Additionally, the squirrel cage design ensures that the rotor can handle high starting currents without significant overheating, making it suitable for a wide range of industrial applications.

Although other types of rotors, such as wound rotors and slip ring rotors, have their specific uses—typically in applications requiring speed control or high starting torque—squirrel cage rotors are preferred for general-purpose applications because they offer a good balance of performance, efficiency, and durability. Permanent magnet rotors, while gaining popularity in certain motor designs, are not as prevalent as the squirrel cage in traditional 3-phase systems.