Why is the practice of operating several alternators in parallel preferred by power-generating stations?

Question

What will be an ideal response?

Answer 1

Power-generating stations operate several alternators in parallel. This practice is preferred to the use of a single large generator for the following reasons:
1. The use of several ac generators means that periodic maintenance and repairs can be made to one alternator. Because the other machines are operating in parallel, they can supply the load and prevent a power interruption due to a generator failure.

2. The load requirements for any central generating station change continually. During light-load periods, the load demands can be met by one or two alternators operating at a high efficiency. This means that these alternators will be operating at a high efficiency. As the load demands increase during certain periods of the day, other alternators can be connected in parallel to meet the peak demands. This procedure is more economical than the use of one huge machine operating, at certain periods of each day, at only a small fraction of its full-load capacity. Such operation results in a low efficiency.

3. Electrical power requirements are continually increasing. To meet these increased demands, utility companies can increase the physical size of their generating plants so that more alternators can be installed. These machines can be operated in parallel with the existing generating equipment. This procedure is a convenient and economical way of increasing the generating capacity of a utility.