Final answer:
The turbine engine starter generator operates primarily in two modes: starter mode, to initiate engine rotation, and generator mode, to produce electrical power. Transition between modes is automatic, and the process of generating electricity in generator mode is similar across different power generation systems, like steam turbines.
Step-by-step explanation:
The turbine engine starter generator operates in two main modes: the starter mode and the generator mode. In the starter mode, the starter generator functions to initiate rotation of the engine's turbine until it achieves self-sustaining speed. Conversely, once the engine reaches the operational speed, the starter generator switches to generator mode. In this mode, it harnesses the mechanical energy from the engine to generate electrical power for various systems of the aircraft or the facility.
Typically, the transition between starter and generator modes is seamless and automatic, often controlled by an external controller or an engine control unit. The conversion of mechanical energy into electrical energy in generator mode is akin to the principle used in electric generators, where a source of mechanical energy, such as steam produced by burning fossil fuels, rotates a coil within the generator, thereby producing electrical current.
In the context of turbines found in power plants, the steam turbine is a common example, where steam produced from water heated by various methods (e.g., burning of fossil fuels, nuclear fission) moves over blades attached to a shaft. This shaft rotation, in turn, rotates the coil within the generator to produce electricity—this process is central to the generation of a vast majority of electricity consumed.