Studies on the Influence of Copper and Insulation Paper on the Accelerated Thermal Ageing of Some Insulating Fluids

Abstract

The behaviour of some insulating fluids in contact with copper foil and / or insulation paper under thermal stress (110�30C for 1000 hours), in a closed system (the access of atmospheric oxygen being limited), has been studied by determining the changes in viscosity and concentration of CO2 and CO. The experimental data revealed that, following the applied heat treatment, the change in viscosity of the esters-based insulating fluids (both synthetic and vegetable) is approximately 7 times lower than in the case of the investigated mineral oils. It has also been found that, following the thermal ageing, the gas content of the mineral oils is substantially higher than in the esters-based oils (8 times higher for CO2 and 4 times higher for CO, respectively). The experimental results indicate superior values for the thermal stability and compatibility with the insulation paper of ester-based insulating fluids.

Studies on the Behavior Some Paints in Electro-insulating Fluid Based on Vegetable Esters

“…Under the practical conditions of operation, under the synergic action of thermal and electric stress, complex interactions between the components of the system leads to a series of processes such as: degradation of electroinsulating paper [1][2][3][4][5][6][7][8][9][10][11], corrosion of metal components, especially copper, with the formation of the products of corrosion that substantially reduces the insulation resistance and dielectric rigidity of the electro-insulating fluid [12][13][14][15][16][17][18][19], the formation of furans products (toxic products determined and monitored by various techniques) [3,8,[20][21][22][23], formation of the inert gases such as CO 2 as well as flammable as H 2 , CH 4 , C 2 H 4 , C 2 H 6 etc. [24][25][26][27][28][29][30][31][32][33][34].…”

“…Several studies [2,4,13,15,17,19,30,33] have highlighted that the copper components of the transformer after thermal oxidation form Cu 2 O films with catalytic effect [35,36] on the processes formation the gases by decomposing the electro-insulating fluid.…”

Thermooxidative Behavior of Some Paint Materials in Natural Ester Based Electro-insulating Fluid

“…Traditionally, mineral oils [1] are used as the electroinsulating fluid in the transformers, a strong biodegradable petroleum derivative [2], which, although having acceptable physical and dielectric characteristics and a relatively low cost, has a number of disadvantages such as: limited thermal stability [3][4][5][6][7][8], corrosive aggressivity due to sulfur content [8][9][10][11][12][13][14][15][16][17], reduced compatibility with the cellulose from Kraft paper -furanic products formation [18][19][20][21][22], relatively low flammability (below 150 o C) and excessive flammable gases formation [30] (high risk of explosions and devastating fires), etc. To increase thermal stability and to reduce the corrosive aggressiveness of electro-insulating oils, manufacturers often use antioxidant additives and / or corrosion inhibitors [15][16][17]31].…”

Effects of Degraded Optical Fiber Sheaths on Thermal Aging Characteristics of Transformer Oil

“…In the process of thermal aging, the main reason for the deterioration of insulating oil is the pyrolysis reaction. Thermal aging experiments have been performed by many researchers over the past decades to study the aging mechanisms of oil and variations of aging parameters [14][15][16][17][18]. However, most studies have focused on the effects of insulating paper, copper, water, and oxygen on the oil.…”