scholarly journals Optimizing characteristics in mineral insulating oil used in high power transformers

2019 ◽  
pp. 222-228
Author(s):  
Irina Alina Chera Anghel ◽  
Loredana Popescu
Keyword(s):  
Mineral Oil ◽  
The Other ◽  
Power Transformers ◽  
Anaerobic Conditions ◽  
Mineral Oils ◽  
Insulating Liquid ◽  
Different Characteristics ◽  
Aerobic And Anaerobic ◽  
Good Heat ◽  
Aerobic And Anaerobic Conditions

The most commonly used insulating liquid in transformers is mineral oil. Special synthetic applications such as silicone, ester, perchloroethene, etc. are used today in special applications, with different characteristics, very low or nonexistent toxicity to mineral oils used in transformers. On the other hand, they have a much better biodegradability than mineral oils in both aerobic and anaerobic conditions. But they cannot directly replace the mineral oil in operation or in repaired units. They have dielectric properties and good heat transfer but have limited their use to special transformers due to the relatively high cost and availability.

Effect of Waste Vegetable Oil on Cooling Performance and Lifetime of Power Transformers

2020 ◽  
Author(s):  
Ehsan Ebrahimnia-Bajestan ◽  
Mohammad Arjmand ◽  
Hani Tiznobaik
Keyword(s):  
Magnetic Energy ◽  
Power Transformer ◽  
Mineral Oil ◽  
Power Transformers ◽  
Cooling Performance ◽  
Mineral Oils ◽  
Waste Vegetable Oil ◽  
Lower Viscosity ◽  
Insulating Liquid ◽  
Main Factor

Abstract During the operation of a power transformer, a large amount of heat is generated due to the electrical and magnetic energy losses in its core and windings, causing a temperature rise in transformers. This generated heat is known as the main factor for aging the electrical insulating system of a transformer. In this research, we numerically studied the ability of a vegetable-based oil — as an alternative coolant for the petroleum-based oils — on the cooling performance of a power transformer. The studied oil was a biodiesel produced from waste cooking vegetable oils, having lower viscosity compared to traditional mineral oils. We also calculated the aging rate of the transformer in the presence of the biodiesel. The results indicated that compared to the mineral oil, the average hotspot temperature of the transformer is 3 degrees lower when the biodiesel was used. The life expectancy of the transformer with the vegetable-based oil was also significantly longer than the case with mineral oil. In conclusion, this study provided a sustainable way to use an eco-friendly material produced from a waste resource as an alternative insulating liquid for the cooling of power transformers.

scholarly journals Cultivable Oral Microbiota in Puppies

2021 ◽  
Vol 65 (3) ◽  
pp. 69-74
Author(s):  
J. Kačírová ◽  
Ľ. Horňáková ◽  
A. Maďari ◽  
K. Mravcová ◽  
M. Maďar
Keyword(s):  
Caesarean Section ◽  
16S Rrna ◽  
Sanger Sequencing ◽  
Caesarean Delivery ◽  
The Other ◽  
Oral Microbiota ◽  
Bacterial Strains ◽  
Anaerobic Conditions ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

Abstract The oral microbiota has been shown to be different in children born by caesarean section and delivered vaginally. The aim of this study was to investigate the oral microbial diversity in healthy puppies and to determine whether the birth mode affects the composition of the oral microbiota. A total of 19 puppies from 4 dams were included in the study. The puppies were divided into two groups depending on the birth mode, vaginal delivery (vaginal born VB) or caesarean delivery (caesar-ean section CS). On the seventh day after birth, swabs of the oral cavity were taken. All samples were analysed by bacteriological cultivation under aerobic and anaerobic conditions. Bacterial colonies were identified by Sanger sequencing of 16S rRNA. A total of 64 bacterial strains belonging to 10 genera were obtained from the oral swabs. The genera Staphylococcus (30.23 % VB and 47.62 % CS) and Enterococcus (25.58 % VB and 33.33 % CS) were the most abundant in both groups. The genera Escherichia (18.60 %) and Enterobacter (16.28 %) were largely present in puppies delivered vaginally, they were not found in puppies born by caesarean section. The other detected genera were present at lower proportions (< 5 %) and varied between the groups. The oral micro-biota of the puppies in the litter was similar, but differed between litters and between groups. Based on these results, we can assume that the birth mode affects the oral microbiota of puppies.

Oxygen concentration affects frequency and range of transconjugants for the incompatibility (Inc) P-1 and P-7 plasmids pBP136 and pCAR1

2020 ◽  
Vol 85 (4) ◽  
pp. 1005-1015
Author(s):  
Kentaro Ochi ◽  
Maho Tokuda ◽  
Kosuke Yanagiya ◽  
Chiho Suzuki-Minakuchi ◽  
Hideaki Nojiri ◽  
...  
Keyword(s):  
Oxygen Concentration ◽  
Anaerobic Condition ◽  
Environmental Samples ◽  
Aerobic Condition ◽  
Recipient Strain ◽  
Donor Strain ◽  
Anaerobic Conditions ◽  
Filter Mating ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

ABSTRACT The frequency of transconjugants were compared for the incompatibility (Inc) P-1 and P-7 plasmids pBP136 and pCAR1 under aerobic and anaerobic conditions. Filter mating assays were performed with one donor strain and one recipient strain using different donors of Pseudomonas and recipient strains, including Pseudomonas, Pantoea, and Buttiauxella. Under anaerobic condition, frequencies of transconjugants for both plasmids were 101-103-fold lower than those under aerobic condition regardless of whether aerobically or anaerobically grown donors and recipients were used. To compare the transconjugant ranges under aerobic and anaerobic conditions, conjugation was performed between the donor of pBP136 and recipient bacteria extracted from environmental samples. Several transconjugants were uniquely obtained from each aerobic or anaerobic condition. Our findings indicate that a plasmid can differently spread among bacteria depending on the oxygen concentrations of the environment.

PRODUCTION AND PROPERTIES OF 2,3-BUTANEDIOL: VII. FERMENTATION OF WHEAT BY AEROBACILLUS POLYMYXA UNDER AEROBIC AND ANAEROBIC CONDITIONS

1946 ◽  
Vol 24f (1) ◽  
pp. 1-11 ◽  
Author(s):  
G. A. Adams
Keyword(s):  
Carbon Dioxide ◽  
Anaerobic Fermentation ◽  
Anaerobic Conditions ◽  
Mechanical Agitation ◽  
Fermentation Time ◽  
Aerobic Conditions ◽  
Ethanol Formation ◽  
Time Required ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

Aeration by mechanical agitation of 15% wheat mash fermented by Aerobacillus polymyxa inhibited the formation of 2,3-butanediol and particularly of ethanol. Aeration of similar mashes by passage of finely dispersed air or oxygen at the rate of 333 ml. per minute per litre of mash increased the rate of formation and yield of 2,3-butanediol but inhibited ethanol formation. However, the over-all time required for the completion of fermentation was not shortened from the usual 72 to 96 hr. required for unaerated mashes. There was no evidence of a shift from fermentative to oxidative dissimilation. Under aerobic conditions, the final butanediol–ethanol ratio was approximately 3:1. Anaerobic conditions, as produced by the passage of nitrogen or hydrogen through the mash, increased the rate of formation of both butanediol and ethanol and shortened the fermentation time to about 48 hr. Under these conditions, the butanediol–ethanol ratio was reduced to about 1.3:1.0. Carbon dioxide gave a butanediol–ethanol ratio resembling that of anaerobic fermentation but did not reduce fermentation time.

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