Electrical strength of pressboard components for transformer insulations

More and more, the insulation systems used in oil-filled transformers consist of oil-impregnated pressboard placed around the low and high-voltage windings and supported by the iron core. This system provides high mechanical stability both in the main and end insulation areas. The thin oil layers within the multilayer pressboard structure result in high electrical strength, which increases with pressboard density. In addition, the oil passing between the individual pressboard components of the insulation structure allows for heat dissipation, so that the necessary electrical and thermal performance may be achieved provided the insulation is sized correctly.