Comparative TG/DTG/DTA+FTIR Studies Concerning the Stability of Some Mineral and Vegetable Electro-Insulating Fluids

Cucos, Andrei; Budrugeac, P.; Lıngvay, Iosif; Bors, Adriana Mariana; Voina, Andreea

doi:10.37358/rc.18.9.6535

Cited by 8 publications

(6 citation statements)

References 2 publications

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“…The results obtained by ATR / FTIR spectroscopy are confirmed by thermal stability investigations performed by DSC analysis of paint samples (figs. [4][5][6].…”

Section: Resultsmentioning

confidence: 99%

“…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].…”

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confidence: 99%

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

Lungulescu¹,

Lıngvay²,

Ungureanu³

et al. 2018

Mat.Plast.

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ATR / FTIR and DSC techniques have been used to evaluate the thermal stability of some ageing paint materials by heat treatment while immersion in natural ester-based electro-insulating oil. Experimental determinations have highlighted the fact that the investigated paint materials (epoxy resins) have a high oxygen affinity and thus, in closed systems (such as power transformers), they oxidize before coming into contact with the transformer oil. This behavior indicates that the paint layer (suitably chosen) applied on the inside of the transformer vat functions as an antioxidant and results in increasing the thermal stability of the oil.

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“…The results obtained by ATR / FTIR spectroscopy are confirmed by thermal stability investigations performed by DSC analysis of paint samples (figs. [4][5][6].…”

Section: Resultsmentioning

confidence: 99%

mentioning

confidence: 99%

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

Lungulescu¹,

Lıngvay²,

Ungureanu³

et al. 2018

Mat.Plast.

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“…When using at impregnating of windings power transformers with mixed insulation, it is necessary that the lacquer be compatible with the used electro-insulating fluid, and not degrade or initiate chemical degradation processes of the electro-insulating fluid [32][33][34][35][36][37].…”

mentioning

confidence: 99%

Comparative Studies on the Electrical and Mechanical Behavior of Some Soldering and / or Impregnation Lacquers

Bors¹,

Lingvay²,

Caramitu³

et al. 2019

Mat.Plast.

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In order to evaluate the behavior in various electrical applications, the main mechanical and electrical characteristics of three different varieties of specifically chosen lacquers - based on alkyl-epoxy-melamine copolymer, the epoxy polymer and polyurethane were compared. From the mechanical determinations, it was found that at ambient temperature the polyurethane lacquer bending resistance was approximately equal to that of the epoxy lacquer and about 6.5 times higher that of the alkyl-epoxy-melamine copolymer. It has also been shown that at bending force of less than 150 Nm the investigated polyurethane lacquer has relatively large deformations of 0.4 mm / kN, which indicates a high capacity to take over relatively high deformations of the metal support (due to thermal expansion from various applications) without significant increasing mechanical stress. The recorded values for the alkyl-epoxy-melamine-based copolymer lacquer and the pure epoxy lacquer are 0.11 mm / kN and 0.03 mm / kN respectively. Determinations by dielectric spectroscopy have shown that at frequencies below 250 Hz the dielectric losses tgd for the epoxy and polyurethane lacquers are approximately equal and are about 2.9 times lower than for the alkyl-epoxy-melamine copolymer lacquer. It was also found that at frequencies higher than 250 Hz the investigated materials behave differently, respectively at the frequency increase up to 10 kHz, the dielectric loss tgd of the polyurethane lacquer remains constant at about 0.0045 in contrast to the epoxide lacquer at which the dielectric loss tgd increases monotone to 0.0095 at 10 kHz, respectively of the alkyl-epoxy-melamine copolymer at which the dielectric loss tgd is approximately constant 0.012 in the 250 Hz-10 kHz range.

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“…Electro-insulating fluids based on mineral oils [54] are traditionally used in electrical equipment, which, although having adequate dielectric and thermal performance at a relatively low price, presents a number of drawbacks to electro-insulating fluids based on vegetable esters (recently developed and tested [55][56][57][58][59][60][61][62][63][64][65][66][67][68]) such as: relatively low flammability point (up to 135 °C) -high fire risk [39], degradation of cellulose from electro-insulating paper with furans formation, very low biodegradability [69].…”

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confidence: 99%

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

Lıngvay¹,

Bors²,

Ungureanu³

et al. 2018

Rev. Chim.

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For the purpose of using three different types of painting materials for the inner protection of the transformer vats, their behavior was studied under actual conditions of operation in the transformer (thermal stress in electro-insulating fluid based on the natural ester in contact with copper for electro-technical use and electro-insulating paper). By comparing determination of the content in furans products (HPLC technique) and gases formed (by gas-chromatography) in the electro-insulating fluid (natural ester with high oleic content) thermally aged at 130 �C to 1000 hours in closed glass vessels, it have been found that the presence the investigated painting materials lead to a change in the mechanism and kinetics of the thermo-oxidation processes. These changes are supported by oxygen dissolved in oil, what leads to decrease both to gases formation CO2, CO, H2, CH4, C2H4 and C2H6) and furans products (5-HMF, 2-FOL, 2 -FAL and 2-ACF). The painting materials investigated during the heat treatment applied did not suffer any remarkable structural changes affecting their functionality in the electro-insulating fluid based on vegetable esters.

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Comparative TG/DTG/DTA+FTIR Studies Concerning the Stability of Some Mineral and Vegetable Electro-Insulating Fluids

Cited by 8 publications

References 2 publications

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

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

Comparative Studies on the Electrical and Mechanical Behavior of Some Soldering and / or Impregnation Lacquers

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

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