Upgrading of generators to improve reliability

In the "good old days" power plant equipment tended to be retired after several years of operation, as more efficient machinery was designed and manufactured. But during the last 25 years or so, because of the increasing cost pressures, and impact of government regulators on plant siting locations, it begins to appear that power plants will never be retired. As a result, many generators that are 30+ years old are still regarded as prime power producers. These generators will usually have components that are badly worn and are becoming increasingly unreliable. The impact of these worn parts on power plant performance is costly in terms of forced outages and unexpected extensions in maintenance outages. These costs are particularly high when the unit is required in order to meet power delivery commitments to the power grid. In these cases, which are becoming all too common, costs of repairs may be in the $100000s, but loss-of-generation costs may be in the $1000000s. This paper addresses common deterioration mechanisms and adverse generator maintenance conditions. The paper then suggests practical ways to reduce exposure to costly generator outages. There may also be efficiency improvements associated with these changes, although the actual change in efficiency cannot be a large number on the generator itself because generators typically operate in the 97 to 99% efficiency range. But even so, on some units and in some situations the cumulative benefits from only a 0.3% improvement in efficiency can approach $1000000 a year.