Patent ID: 6276222
Filing Date: 2001-08-21
Classification: G01N,H01F,Y02A

Abstract:
A method of evaluating deterioration of insulating paper, the method comprising subjecting kraft insulating paper to insulating oil at a heating temperature of not more than 110.degree. C. to deteriorate said kraft pulp insulating paper and to determine physical and/or chemical properties of said kraft pulp insulating paper in order to use said physical and/or chemical properties as an index, wherein said physical and/or chemical properties are the polymerization degree or the decomposition rate of the insulating paper;the method further comprising measuring the heating temperature and the time (years) of heating, and calculating the polymerization degree, said polymerization degree being expressed by the following evaluation equation:D=D.sub.0.times.10.sup.-N.times.10.sup..sup.{-A/(273+T)+B}wherein, 1925.ltoreq.A.ltoreq.1930, 3.6 5.ltoreq.3.7; D is the polymerization degree of the insulating paper, D.sub.0 is the initial polymerization degree of the insulating paper, N is the number of years of heating and t is the heating temperature (.degree. C.).