METHOD OF ASSESSMENT OF THE STATE OF PAPER INSULATION OF THE OIL-FILLED ELECTRICAL APPARATUS Russian patent published in 2018 - IPC G01N30/02 

FIELD: electric power engineering.

SUBSTANCE: invention refers to the electric power industry, systems for assessing the technical condition of transformer equipment of power plants and substations, in particular to methods for assessing the state of paper insulation of oil-filled electrical apparatus, for example, power transformers. Stated method of operative assessment of the paper insulation condition of oil-filled electrical apparatuses includes the detection of the function of the degree of polymerization of paper insulation from the specific volume of methanol in the transformer oil, as well as measuring the concentration of methanol that is dissolved in the transformer oil. Measurement of the concentration of methanol that is dissolved in the transformer oil includes the following: sampling of transformer oil in the volume of at least 100 ml; measuring and fixing the temperature of the sample of transformer oil; subsequent heating of the sample to the temperature above the boiling point of methanol; the subsequent extraction of methanol from the sample by means of bubbling with the inert gas at the bubbling rate, which is sufficient to extract at least 99.5% of methanol in 2 hours; concentration of methanol, which is contained in the sample of the transformer oil, in the cryotrap that is located in liquid nitrogen; dissolution of methanol precipitated on the walls of the cryolab in the liquid solvent; selection of the methanol solution in the liquid solvent with the micro-syringe; the introduction of the solution of methanol in the liquid solvent into the gas chromatographic system; measuring the concentration of methanol through a gas chromatographic system equipped with capillary columns and flame ionization detector, for the time that is sufficient for the passage of methanol molecules along the gas path of the gas chromatographic system to the flame ionization detector. Method also includes determination of the specific volume of methanol according to the formula: , where Q₀ is the specific volume of methanol, μl/kg; C_meas is the measured value of the methanol concentration in the oil sample, ppb; m_oil is the weight of oil in the oil-filled electrical apparatus, kg; ρ_oil is oil density, kg/m³; m_paper is the weight of paper insulation in the oil-filled electrical apparatus, kg; ρ_paper is density of paper insulation, kg/m³; K_dis.pap(T) is the coefficient of distribution of methanol between oil and paper when the equilibrium state is reached; C_met.deg is the measured value of the methanol concentration in the oil sample from the oil-filled electrical apparatus immediately before the oil treatment, ppb; η is the coefficient reflecting the efficiency of methanol removal during oil treatment; k is the number of oil treatments during the operation of the oil-filled electrical apparatus. Degree of polymerization of the paper insulation is then determined in accordance with the function of the specific volume of methanol depending on the degree of polymerization of the paper insulation and in the final stage of the process, the paper insulation condition is evaluated based on the degree of polymerization of the paper insulation that is determined according to the schedule.

EFFECT: technical result is the increase in the efficiency and reliability of assessing the state of paper insulation of oil-filled electrical apparatuses without their decommissioning.

4 cl, 4 dwg, 3 tbl