Refurbishment of turbine generators

There are two possible strategies which can be applied to the refurbishment of turbine generators: the unit is operated until there is a breakdown or a serious fault is discovered during maintenance, the repair/corrective modification is then applied to all similar units during subsequent planned outages; or, the generator is completely refurbished for a specified extended design life with accompanying technical and commercial assurances. Recently, generating utilities have embarked on the second strategy and the main part of the authors´ work concentrates on the scope of work necessary for complete refurbishment. An outline is given of the inspection and analytical methods used in the revalidation of the stator fabrications and rotor forging. The replacement of materials with modern alternatives is discussed and design changes to improve the reliability and flexibility of the unit are also considered