Detections And Studies On Characteristic Products Of Transformer Solid-insulation Aging

As an important component of the power system,transformer is closely related to the normal operation of the whole power grid.It is crucial to monitor the operation condition of the transformer in time.At present,degree of polymerization and furfural are usually used as detection index of the transformer,but it is also difficult to detect and the accuracy is low in practice.Methanol is the first product of decomposition of cellulose and has good thermal stability,at the same time,it have higher content in the early aging,in that case it can be used as the aging characteristics of products.At that point,we attempted to use methanol content as a new index of transformer aging,compared with the degree of polymerization and furfural detection,to verify the feasibility and innovation of methanol as a transformer testing indicators.Actual operating environment of transformer is simulated to explore the gradual process of polymerization degree of insulation paper aging under the condition of 130?.Degree of polymerization is measured by ubbelohde viscometer at different time points.It is concluded that the polymerization degree of insulation paper drop quickly at the beginning of aging.When the aging time is more than 50 days,the degree of polymerization slow down as time goes on,and the aging basically end at 180 day.Furfural in oil is detected by multichannel ultraviolet–visible spectroscopy,with extraction pretreatment.Methanol extract and oil volume ratio is 1:1,centrifugation and set aside for 30 minutes are the best pretreatment conditions.In the ideal transformer oil,we can find a highest absorption peak at 270 nm for furfural,but the peak is seriously disturbed due to the addition of BHT(butylated hydroxytoluene).It is found that the addition of TBA(2-thiobarbituric acid)can react with furfural to form a yellow compound,and a obvious absorption peak can be found at 392 nm.A spectrum detection method is designed to measure the methanol content in water,then it is used in the oil phase.The optimum experimental conditions are as follows: keep 2.5 mL sulfuric acid and 0.5 mL potassium permanganate with methanol for 10 min.then sodium carbonate is added to neutralize solution;add the chromotropic acid(with molar ratio of methanol to 3.2:1),then add 6 mL concentrated sulfuric acid.Under the optimum experimental conditions,the optimum absorbance of the final product can be detected at the wavelength of 554.55 nm,and the correlation of the standard curve is fine.The use of methanol content as the indexes of the Karamay No.25 transformer oil,is verified ideally,and the methanol recovery percentage is 98-102%,the precision is 4-5.5%.There is the feasibility of this method in actual detection of methanol content in oil of aged transformer.