PROCEDURE EVALUATING DEGREE OF THERMAL AGEING OF INSULATING PAPER Russian patent published in 2004 - IPC

FIELD: tests of insulating paper. SUBSTANCE: procedure includes taking of luminescence spectrum of specimens of insulating paper subjected to additional thermal ageing in temperature range from 100 to 180 C, excitation of luminescence by luminous flux with wave length between 250-500 nm, recording of emission in range from 300 to 700 nm, measurement of luminescence intensity and construction of curves of dependence of luminescence on time of accelerated ageing at different temperatures. From them values of constant K of rate of decrease of luminescence is found. Value of multiplier A, effective activation energy W and constant K_o of ageing rate corresponding to operational temperature are found from relation K=A exp(-W/RT). Then residual life τ_res is determined by relationship τ_res = 1/K_o•ln(I_t/I_b.s), where I_b.s is minimum permissible value of luminescence intensity corresponding to breaking state of paper; I_t is value of luminescence intensity corresponding to initial state of paper for which degree of ageing is evaluated. Degree of ageing is judged by share of used life. EFFECT: increased authenticity of evaluation of degree of ageing of insulating paper. 3dwg