J & P Transformer Book, 13th Edition

5 Testing of transformers

5.1 TESTING AND QUALITY ASSURANCE DURING MANUFACTURE

Unlike many items of power system electrical plant (e.g. switchgear and motors) most transformers are still virtually handmade, little or no mass production is employed in manufacture and each is produced very much as a one-off. This means that the user cannot rely on extensive type testing of pre-production prototypes to satisfy himself that the design and manufacture renders the transformer fit for service, but must have such proving as is considered necessary carried out on the transformer itself. From a series of works tests, which might at most be spread over a few days, it is necessary to ascertain that the transformer will be suitable for 30 years or more ...