Study On Characteristic Products Of Solid-insulation Aging Of Power Transformer

Furfural is one of the degradation products of solid insulation aging in the transformer. The method of examining its concentration has been used widely to judge the degree of aging transformer in the world. But it still has many insufficiencies. Firstly, lots of furfural will be filtered out after the filteation treatment of transformer oil, so that the concentration of furfural will be caused great lost of the oil. And how to judge the degree of solid insulation aging after filteation treatment has not been a long-term solution question. Secondly, the concentration of furfural in the transformer is a long-term process of accumulation, which reflects a long-term running status of the transformer. But it cannot reflect the short-time thermal state of the actual operation transformer. Therefore, scholars of various countries are actively trying hard to find the other aging characteristics products to realize a earlier, more accurate judgment of the transformer aging.In this paper, sugar is confirmed as the first step decomposition products of cellulose by the theoretical analysis of degradation pathway of cellulose. It is generated earlier than the furfural. So sugar testing is established as a primary mission. However, the results of furfural concentration and sugar concentration testing of the actual oil sample show that there are only two kinds of sugar in the transformer oil. They are ribose and fucose.What's more, the experimental results demonstrate that the concentration of the ribose and fucose in the oil is little to aging state of the transformer, and there is also no relationship between the concentration of furfural and the two sugars. Consequently, ribose and fucose cannot be regarded as efficient characteristics products to measure the degree of the transformer aging.Simulative aging device is established to study the composition and concentration of the aging degradation products of solid insulation with different experimental conditions. The results show that: (1) Both furfural and 5-hydroxymethylfurfural come from the aging decomposition of solid insulation, and transformer oil's aging decomposition cannot produce furfural and 5-hydroxymethylfurfural. And the higher the temperature is, the more the concentration of furfural and 5-hydroxymethylfurfural increases; (2)The drastic changes of furfural and 5-hydroxymethylfurfural's concentration can be used to judge whether over-temperature situation appears in the transformer oil in the short term.The certain concentration of furfural and 5-hydroxymethylfurfural are mixed, and the mixed-oil samples are configured for oil-filtering experiment which in order to study that how the oil-filtering impact on the concentration of furfural and 5-ydroxymethylfurfural. The results suggest that the quality of furfural and 5-hydroxymethylfurfural adsorbed by unit mass of filter paper is 0.227 mg/g and 0.331 mg/g; the quality of furfural and 5-hydroxymethylfurfural adsorbed by unit mass of 801 adsorbent is 0.138 mg/g and 0.086 mg/g.