In a squirrel-cage rotor, how are the bars typically secured?

In a squirrel-cage rotor, the bars are typically secured by short-circuiting them at both ends. This design is fundamental to the operation of the rotor in an induction motor. The ends of the bars are connected by short-circuiting rings, which not only secure the bars in place but also allow the current to flow through the bars. This configuration is crucial because it helps create the magnetic field necessary for the rotor to interact with the stator's magnetic field, enabling efficient operation of the motor. By using short-circuiting, the design ensures that the rotor can effectively convert electrical energy into mechanical energy through the induced electromagnetic forces.

Other methods such as welding, bolting, or gluing are not typically used in this context, as they would not provide the necessary electrical connection or mechanical robustness needed for the rotor's function. In summary, short-circuiting the bars at both ends optimally secures them and facilitates effective performance in squirrel-cage rotors.