What is a key feature of a synchronous generator?

A synchronous generator is specifically designed to operate at a constant speed, which is synchronized to the frequency of the electrical grid it supplies. This constant speed allows it to maintain a steady output of electrical energy while converting mechanical energy—often generated by turbines powered by steam, water, or gas—into electrical energy.

The mechanical energy input to a synchronous generator must match the synchronous speed dictated by its design and the system frequency, resulting in efficient energy conversion. This ability to maintain a constant operating speed is essential for the stability of power systems, as fluctuations in speed could lead to issues such as frequency instability or unsatisfactory performance of the machinery connected to the grid.

Other features mentioned in the choices do not apply to synchronous generators, as they depend on stable rotor speed for their operation. Consequently, the focus on constant speed for energy conversion is what distinctly characterizes synchronous generators in the context of electrical systems.