What are wound rotors used for in electrical machines?

Wound rotors are specifically designed to enhance the performance of electrical machines, particularly in applications that require variable speed and high starting torque. The primary function of wound rotors is to facilitate electromagnetic induction, which is the principle that allows electrical energy to be converted into mechanical energy and vice versa.

In a wound rotor, the rotor windings can be connected to external resistances, allowing for better control of the rotor speed and torque. This feature is especially useful in applications like cranes and mills, where high starting torque is necessary. The ability to adjust the resistance in the rotor circuit influences the amount of current flowing through the rotor windings, thereby optimizing the electromagnetic field and resulting torque.

This ability to manage electromagnetic induction effectively distinguishes the role of wound rotors from structural support, mechanical transmission, and heat dissipation, which are functions not directly related to their primary design purpose.