In a synchronous generator, a divided winding rotor is preferable to a conventional winding rotor because of increased steady-state stability limit.

A synchronous generator is a device that converts mechanical energy into electrical energy by utilizing the principle of electromagnetic induction. It consists of a rotor and a stator. The rotor is the rotating part, while the stator is the stationary part.

A divided winding rotor refers to a rotor design that has multiple winding sections that are electrically isolated from each other. This is in contrast to a conventional winding rotor, which has a single continuous winding.

Increased Steady-State Stability Limit:
The steady-state stability limit of a synchronous generator refers to its ability to maintain synchronism and operate without any stability issues under normal operating conditions. A higher steady-state stability limit means that the generator can handle larger electrical loads without losing synchronism.

The divided winding rotor design offers several advantages that contribute to an increased steady-state stability limit:

1. Reduced Rotor Heating: The divided winding rotor design allows for better cooling and heat dissipation. The presence of air gaps between the winding sections enables improved airflow, which helps in reducing rotor heating. This, in turn, prevents thermal stress and ensures better stability during operation.

2. Increased Mechanical Strength: The divided winding rotor design provides increased mechanical strength compared to a conventional winding rotor. The multiple winding sections are mechanically independent, which means that any mechanical faults or failures in one section are less likely to affect the overall stability of the generator. This enhanced mechanical strength contributes to a higher steady-state stability limit.

3. Improved Fault Tolerance: In the event of a fault or short circuit in one winding section, the divided winding rotor design allows the remaining sections to continue operation unaffected. This fault tolerance capability reduces the chances of complete generator failure and ensures the stability of the system.

4. Enhanced Damping: The divided winding rotor design also provides better damping characteristics. Damping refers to the ability of the generator to resist oscillations and maintain stable operation. The presence of multiple winding sections with isolated windings helps in dissipating any oscillatory energy and provides better damping, thereby increasing the steady-state stability limit.

Overall, the divided winding rotor design offers improved cooling, increased mechanical strength, enhanced fault tolerance, and better damping characteristics. These factors contribute to an increased steady-state stability limit, making it a preferable choice over a conventional winding rotor in synchronous generators.