Condition of cellulose insulation in oil immersed transformers after factory acceptance test

Due to the large magnitude of the investments involved, in particular for large power transformers, it is of vital interest to ensure that the buyer gets a transformer that is fit for service. There are, however, no agreements or guidelines of what shall be expected from a new transformer in terms of solid insulation properties. The purpose of this brochure is to provide the industry with a guide for checking material properties of cellulose insulation at the point when the transformer leaves the factory that is relevant for problem free and long future operation of the transformer.