ABSTRACT
Any ac power system begins with a generating source. Electric generators are devices that convert energy from a mechanical form into an electrical form. This process, known as electromechanical energy conversion, involves magnetic fields that act as an intermediate medium. The input to the generating machine can be derived from a number of energy sources. For example, in the generation of large-scale electric power, coal can produce steam that drives the shaft of the machine. Typically, for such a thermal process, only about 1/3 of the raw energy (i.e., from coal) is converted into mechanical energy. The final step of the energy conversion is quite efficient, with efficiency close to 100%.
