METHOD FOR LIFE EXTENSION OF CELLULOSE INSULATION IN POWER TRANSFORMERS OF ELECTRICAL APPARATUSES

摘要

The present invention relates to a method for delaying the ageing, or lower the rate of degradation and loss of physical strength, of a cellulosic insulation e.g. used in an apparatus such as a power transformer, an electrical apparatus or an electrical cable. The invention is achieved by that at least two ageing inhibitors in the form of active chemical substances are added to the oil in the apparatus and at least partly be absorbed by the cellulosic insulation, a first active chemical substance is a buffer substance, such as oil soluble amines- or ammonium salts, and a second active chemical substance is an oil soluble alcohol, and thereby achieving a deceleration of both the acid hydrolyses process and the oxidation process resulting in a lower rate of cellulose degradation and maintaining the strength of the cellulosic insulation.