Research of thermal stability of the VG transformer oil in the presence of individual sulfides

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In connection with the known negative impact of organosulfur connections on quality of transformer oils and the corresponding rise in price of their production including various ways of cleaning of oil fractions of organosulfur connections re-searches of structural and group structure of oil organosulfur connections and their influence on operational properties of transformer oil have been conducted. Influence of individual sulfides on thermal stability of the brand VG transformer oil in electric field is studied by tension of 30 kV/cm at change of concentration of sulfides in range from 0 to 1,0% from the mass of oil. The research was con-ducted with use of methylbenzylsulfide and a metilfenilsulfide on the basis of the brand VG transformer oil without addition of an ionol. It is established that individual sulfides metilbenzil- and metilfenilsulfide treat the anti-oxidizing additives reducing oil aging speed. For obtaining the maximum thermal stability of transformer oil the optimum concentration of individual sulfides making 0,5% of the mass of oil is defined. The analysis of the inhibiting ability metilbenzil-and a metilfenilsulfida has shown that more effective additive to oil is methylbenzylsulfide which increases thermal stability of oil and reduces amount of the absorbed air more (by 2,2 times) in comparison with the metilfenilsulfide, 0,5% of the mass of oil taken at the optimum concentration equal. The carried-out comparative analysis of a molecular structure of methylbenzylsulfide and metilfenilsulfide has shown that with an identical length of a paraffin chain replacement of a naphthenic cycle by an aromatic kernel leads to decrease in efficiency of individual sulfide as anti-oxidizing additive to oil.