Generator reliability as influenced by engineering design parameters

In recent years, power-plant life expectancy has extended beyond 40 to 50 years, including on large, high-duty generating equipment. Simultaneously, commercial pressures have lead generator designers of new equipment to: (1) reduce safety and duty margins; (2) move toward higher stress levels; and (3) increase the rate of implementation of new design concepts. The net effect has been a negative impact on generator reliability and life expectancy, and has lead to a significant increase in maintenance costs. In this paper, the impacts of the four basic deterioration mechanisms on generators are considered (TEAM): thermal, electrical, ambient, and mechanical. Only those design factors directly relating to deterioration are considered. These topics are discussed rather comprehensively but in relatively nontechnical terms. A better understanding of these deterioration mechanisms should assist owners of generators to implement better operating and maintenance practices, and thus reduce maintenance costs and extend reliable life of the generator.