How much more power can be produced by refurbishing older projects?

In some situations, increased rating and efficiency can be obtained by runner replacement. For pre-1960 turbines, it is frequently possible to obtain output increases as high as 30 percent, and efficiency increases of more than 5 percent, by replacing existing runners with runners of improved design.

The former requirement that generators deliver rated output with no more than a 60C temperature rise, and the conservative safety factors provided by early generator manufacturers, result in the possibility of substantial increases in machine capacity by installing windings using modern insulation technology which can provide increased electrical capacity with the same physical size as earlier manufactured windings.

Therefore, it is often possible to increase the capacity of older units by installing new stator windings and improved runners, and by upgrading various auxiliary equipment. Apart from technical limitations, the economic value of capacity is most important in justifying a refurbishment.

The practical limit of uprating is reached when the cost of replacing equipment to obtain additional capacity equals the economic worth of that added capacity.

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