Insulation condition during transformer manufacturing

The main objective of this reference paper is to identify gaps in knowledge and issues in relation to verification of cellulosic insulation material properties during and after manufacturing of oil/cellulose insulated power transformers and shunt reactors. It provides input for future work in this field. In addition, it also provides the reader with an overview of this area. Along with the identified gaps, some aspects are discussed in more detail, e.g. physical material parameter(s) that are relevant for a transformer to withstand stresses in service, end-of-life definitions and measurement techniques.

The paper is focused on oil-cellulose insulated, medium- or large power transformers, reactors and similar equipment. It is also confined to cover cellulose properties and their…