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The use of natural ester–filled transformers started in 1996, with two industrial transformers installed at the Cooper Power System factory to provide power for two core annealing ovens. Investigations conducted according to the IEEE C57.100 accelerated transformer life test method (Lockie Test) [1] and the sealed tube accelerated insulating system material life test method [2]–[4] indicated a possible extension of transformer life, associated with reduction of the paper degradation rate when impregnated with natural ester liquids. [ABSTRACT FROM AUTHOR]

For decades, petroleum-based mineral oils are the insulating media conventionally used in the industry, particularly for high voltage (HV) applications. However, due to the disadvantages of mineral oils, there is growing interest in replacing these oils with environmentally friendly alternatives in order to fulfill the demanding requirements of dielectric liquids. One of the promising substitutes for mineral oils is ester oils. Nevertheless, the implementation of ester oils is not widespread compared with mineral oils due to the lack of understanding on the performance of ester oils in HV applications. Hence, the objective of this study is to investigate the bridging phenomenon of two dielectric liquids with different viscosities: palm fatty acid ester and mineral oil under the influence of direct current electric field. The results show that oil viscosity plays an important role in the formation of cellulose bridge and breakdown behavior. [ABSTRACT FROM AUTHOR]

The mechanical performance of two commercial papers used as solid insulation in power transformers, namely standard Kraft and a thermally upgraded Kraft paper, were studied during accelerated aging in Luminol oil at 170 ?C. The results show a relationship between the degree of polymerization and the mechanical properties measured by tensile testing. A linear relationship was found between the mechanical properties of paper, the tensile index (Tidx), and the concentration of methanol present in the oil. The methanol chemical marker has been proven to be an accurate assessment tool for the aging of cellulosic paper. The results show a promising tool for correlating the methanol concentration in oil, as an indirect indicator, with the mechanical performance of the paper. This approach can be used to monitor the real state of the cellulose chains in the power transformer insulation paper. [ABSTRACT FROM AUTHOR]

The degree of crystallinity in the matrix formed by cellulose acetate (CA) and lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) were reduced by embedding with deep eutectic solvent (DES) which is a type of ionic mixture synthesized from choline chloride and urea in a specific ratio. The fabrications of thin films were done by solution casting technique. The sample with composition of CA:LiTFSI:DES (28 wt%:12 wt%:60 wt%) appears as the highest conducting sample with the calculated value of 2.61 × 10 S cm at ambient temperature. This high conducting sample possesses low relative viscosity so as to have high ion fluidity of 0.19. SEM micrographs were used to study the structural alternation that took place in the presence of DES at different ratio in the polymer electrolytes matrix. The dielectric loss tangent plot reveals the low relaxation time for high conducting sample which has immense movements of lithium conducting ion (Li). The enhancement in the ionic conductivity of the DES plasticized samples with temperature obeys Arrhenius rule. [ABSTRACT FROM AUTHOR]

The article discusses cellulose insulation as the most preferred solid insulation in power transformers due to availability of resources. The major disadvantage of cellulosic material for electrical purposes is that its absorptive properties and needs to be maintained dry. According to G. T. Kohan of Bell Telephone Laboratories in New York, the use of cellulose in electrical applications such as HV power cables and power transformers has led to the increase in the annual consumption of cellulose insulation.

Cellulose insulation has rapidly gained a large market share among general contractors and homeowners. Recent interest regarding health effects of high concentrations of fungi within indoor environments (building-related illnesses or sick building syndrome) has promoted concern about susceptibility of building materials, including wood products (in general) and cellulose insulation (specifically), to fungal attack. This study reports an assessment of fungal growth on cellulose insulation made from recycled paper and treated with varying concentrations of sodium polyborate within half-scale wall units exposed to variable and high ambient temperatures and relative humidities throughout the summer. Boron-treated and untreated (control) cellulose insulation within the wall units were challenged with a suspension containing high concentrations of spores of five fungal species commonly found in indoor environments. Our results suggest that cellulose insulation treated with sodium polyborate (a) precludes the growth of the five common fungal species; (b) harbors fewer fungal species before and after being challenged with the fungal spore suspension; and (c) is likely having a cytotoxic or sporocidal effect on many, if not all, fungal species. These results suggest that cellulose insulation treated with sodium polyborate, when properly applied and installed, precludes fungal growth for at least 124 days at high temperatures and relative humidities. [ABSTRACT FROM AUTHOR]

Part I. Shows the influence of air and oil type on the aging of pressboard insulation for transformers under the influence of a considerable amount of moisture. Gas-in-oil analysis of pressboard-oil system; Methane; Carbon monoxide; Carbon dioxide; Effect on partial discharge; Furane production; Dependence of the effects on the absence or presence of oxygen.

Presents the introductory editorial for this issue of the publication. [ABSTRACT FROM AUTHOR]

In this work, the total ionizing dose (TID) effect on 130 nm partially depleted (PD) silicon-on-insulator (SOI) static random access memory (SRAM) cell stability is measured. The SRAM cell test structure allowing direct measurement of the static noise margin (SNM) is specifically designed and irradiated by gamma-ray. Both data sides’ SNM of 130 nm PD SOI SRAM cell are decreased by TID, which is different from the conclusion obtained in old generation devices that one data side’s SNM is decreased and the other data side’s SNM is increased. Moreover, measurement of SNM under different supply voltages (Vdd) reveals that SNM is more sensitive to TID under lower Vdd. The impact of TID on SNM under data retention Vdd should be tested, because Vdd of SRAM cell under data retention mode is lower than normal Vdd. The mechanism under the above results is analyzed by measurement of I—V characteristics of SRAM cell transistors. [ABSTRACT FROM AUTHOR]