Quality assurance and in-house testing [transformer life management]

A power transformer´s life begins at the factory and its future performance will be heavily influenced by the care and skill exercised during the whole manufacturing process, from design through to installation. Quality assurance systems attempt to ensure that this care and skill is applied in a continuous and consistent manner. Also, importantly, these systems should seek to continuously improve the level of care and skill and hence the quality of the product. Could we then, come to a situation, where quality assurance replaces testing? To an extent this already happens in that type tests are often only carried out on the first off of a new design on a particular contract or even sometimes on a similar unit produced for a different contract. In accepting this situation it is implicit that the level of quality required to be demonstrated on the type tested unit has been maintained for the subsequent units. Could this approach be extended to remove the requirement for routine tests or at least reduce them to a sample basis? Apart from the fact that some tests yield useful information for future life management and condition assessment there are a number of reasons why this would be ill advised. These reasons are briefly outlined. Quality assurance and in-house testing should therefore be seen as two essential complementary elements that contribute towards the long-term life management of the transformer. These two elements are considered in some detail