抄録
Electrical insulating paper for high voltage cable was heated in the air of the temperatures of 110°C to 210°C, and its dielectric and chemical properties were measured.
(1) The dielectric property of dry paper at the high temperatures is remarkably affected by heating in the air.
When it is heated in the air of the temperatures of 110°C and 130°C, the dielectric loss decreases up to 120 hours with heating time.
(2) Although there is certain degradation of fibers composing paper, dielectric property has come to be better and up to D. P. of about 800 it becomes to be better with the decrease of D. P..
(3) Under the same condition of degradation of fibers, when it is heated in the temperatures of 110°C to 130°C, the dielectric loss is the best.
(4) Carboxyl groups decrease continuously with heating time, but start to increase after it is severely heated.
(5) Velocity constants of decomposition of fibers composing paper were obtained from the changes in D. P., and activation energy calculated by them is 29.6kcal/mol.
