scholarly journals The evolution of breakdown voltage and delay time under high overvoltage for different types of surge arresters

2021 ◽  
Vol 34 (2) ◽  
pp. 307-322
Author(s):  
Emilija Zivanovic ◽  
Marija Zivkovic ◽  
Milic Pejovic
Keyword(s):  
Breakdown Voltage ◽  
Delay Time ◽  
Number Density ◽  
Component Reliability ◽  
Surge Arresters ◽  
Dc Discharge ◽  
Low Concentrations ◽  
Different Types ◽  
Detailed Statistical Analysis ◽  
Qualitative Observation

The results of the reliability testing of Littelfuse and EPCOS gas-filled surge arresters for different overvoltages under DC discharge will be presented in this paper. The static breakdown voltage of these gas components was estimated using voltage increase rates ranging from 1 to 10 V/s. A detailed statistical analysis of experimental data has also been done. The delay time of these components for different nominal overvoltages has been investigated as an additional aspect important for component reliability. In addition, the delay time method was used as a statistical method which can give neither ion nor neutral active states number density in the glow and afterglow. It can be employed for qualitative observation of ions and neutral active states decay in the afterglow to such low concentrations where the other methods cannot be applied. Finally, a comparison has been done between the characteristics of two gas-filled surge arresters which have the same nominal overvoltage (Littelfuse and EPCOS) from different manufacturers.

scholarly journals Influence from cosmological uncertainties on galaxy number count at faint limit

2015 ◽  
Vol 30 (28) ◽  
pp. 1550139
Author(s):  
Keji Shen ◽  
Qiang Zhang ◽  
Xin-He Meng
Keyword(s):  
Galaxy Evolution ◽  
Number Density ◽  
Number Count ◽  
Density Prediction ◽  
Evolution Pattern ◽  
Wide Range ◽  
Different Types ◽  
Physical Cosmology ◽  
Cosmology Observations ◽  
Near Future

Counting galaxy number density with wide range sky surveys has been well adopted in researches focusing on revealing evolution pattern of different types of galaxies. As understood intuitively the astrophysics environment physics is intimately affected by cosmology priors with theoretical estimation or vice versa, or simply stating that the astrophysics effect couples the corresponding cosmology observations or the way backwards. In this paper, we try to quantify the influence on galaxy number density prediction at faint luminosity limit from the uncertainties in cosmology, and how much the uncertainties blur the detection of galaxy evolution, with the hope that this trying may indeed help for precise and physical cosmology study in near future or vice versa.

scholarly journals Some chemical and bacterial characteristics of bottom deposits from lakes and estuaries

1953 ◽  
Vol 51 (2) ◽  
pp. 185-194 ◽  
Author(s):  
L. A. Allen ◽  
J. Grindley ◽  
Eileen Brooks
Keyword(s):  
Bacteriological Examination ◽  
Surface Layers ◽  
Digested Sludge ◽  
Faecal Pollution ◽  
Bottom Deposits ◽  
Low Concentrations ◽  
Different Types ◽  
Different Depths ◽  
Micro Organisms ◽  
Reducing Bacteria

Chemical and bacteriological examination of muds from sources differing widely in the degree of pollution to which they were subject showed great differences in the contents of carbon, nitrogen and sulphide. These differences were not correlated with differences in the severity of faecal pollution. The amount of organic matter available for growth of micro-organisms in the mud of different depths was not reflected in the figures for organic carbon. A convenient index of this factor was obtained by measuring the volume of gas evolved during anaerobic digestion over a prolonged period of incubation. The rate of evolution was increased by the addition of an inoculum of digested sludge from a sewage works.Sulphate-reducing bacteria appeared to be of two different types. In samples of mud from fresh-water lakes much higher counts were usually obtained in a medium containing comparatively low concentrations of inorganic salts and of lactate than in a medium containing much higher concentrations of these constituents. In samples from locations where conditions were more saline the reverse was usually true.Counts of Bact. coli and of Strep, faecalis together probably constitute the best index of faecal pollution in the examination of samples of mud. These organisms are, however, largely confined to the surface layers.

scholarly journals Investigation on the Breakdown Characteristics of Different Types of Lightning Rods

2018 ◽  
Vol 17 (2) ◽  
pp. 1-5
Author(s):  
Noor Azlinda Ahmad ◽  
Rosniza Zainal ◽  
Zuraimy Adzis
Keyword(s):  
Breakdown Voltage ◽  
High Voltage ◽  
Horizontal Distance ◽  
Different Types ◽  
Series Of Experiments ◽  
Voltage Breakdown

This paper investigates the voltage breakdown characteristics of three types of lightning rods - blunt, sharp and flat. The objectives of this study are to determine the voltage breakdown characteristics of various types of lightning rods and to obtain the striking distance of each rod. A series of experiments were conducted in the high voltage laboratory consisting of individual testing rod, competitive testing rod and also horizontal distance changing. All three types of rods have been tested in each experiment in order to obtain a comprehensive result. The blunt rod has been proven as the best strike receptor in comparison to sharp and flat rod. This is because breakdown voltage for blunt rod is much lower (199 kV) than that of flat and sharp rod. Therefore, replacement of widely used sharp rod with the blunt one should be considered in order to provide better protection for buildings from lightning activities. 

Influence of cathode material type on the electrical breakdown behaviors of DC discharge

2020 ◽  
Vol 98 (8) ◽  
pp. 726-731
Author(s):  
F. Diab ◽  
W.H. Gaber ◽  
M.E. Abdel-kader ◽  
B.A. Soliman ◽  
M.A. Abd Al-Halim
Keyword(s):  
Cathode Material ◽  
Work Function ◽  
Breakdown Voltage ◽  
Cathode Materials ◽  
Electrical Breakdown ◽  
Ionization Efficiency ◽  
Parallel Plates ◽  
Maximum Value ◽  
Dc Discharge ◽  
Work Functions

Paschen curves were studied using different cathode materials such as magnesium, zinc, and carbon graphite by discharge in argon gas of a pressure range between 0.08 and 3 Torr using a parallel plates configuration. The first and second Townsend coefficients (α and γ, respectively) and the ionization efficiency (η) of different cathode materials were deduced from Paschen curves as a function of the reduced field (E/P). The minimum breakdown voltage was found to be about 242 V for Mg material, which has the lowest work function, while carbon graphite has a higher breakdown voltage of 283 V due to its higher work function. The second coefficient γ was increased as a function of E/P and has higher values for materials of lower work functions, and a similar trend of γ is obtained as a function of the ion mean energy. On the other hand, the first coefficient α has a reverse behavior with both E/P and the work function of the cathode materials compared with the second coefficient. The ionization efficiency of the three cathode materials is identical, as η depends only on the gas properties and not the cathode material. η has a maximum value of about 0.025 V−1 for an E/P of about 185 Vcm−1Torr−1, corresponding to the maximum ionizing ability of electrons. The validation of the breakdown results has been confirmed by conferring with other published experimental measurements.

Effect of two bio-polysaccharides on organogenesis of protocorm-like bodies in Phalaenopsis cultured in vitro

2020 ◽  
Vol 26 (1) ◽  
pp. 2137-2142
Author(s):  
A. M. Meskatul ◽  
K. Shimasaki ◽  
S. U. Habiba
Keyword(s):  
Shoot Formation ◽  
Vital Role ◽  
White Led ◽  
Fresh Weight ◽  
High Concentration ◽  
Low Concentrations ◽  
Different Types ◽  
Modified Ms Medium ◽  
Led Lights

Different types of bio-polysaccharide play a vital role in the growth of PLBs cultured in vitro. In this study, to we investigated the potential impacts of two bio-polymers,: hyaluronic acid (HA9) and sodium alginate (ALG) on the organogenesis of protocorm-like bodies (PLBs) in Phalaenopsis under white LED lights. PLBs of Phalaenopsis ‘Fmk02010’ were explanted on modified MS medium with different concentrations of HA and (ALG). The highest average number of PLBs per explant (24.6) was recorded for ALG alone at a concentration of 0.01mg/L, and the fresh weight was also highest at the same concentration. The combination of 0.01mg/L ALG and 0.01mg/L HA also resulted in a large number of PLBs (23.8) and high fresh weight. As opposed to, the highest number of shoots /explant (3.6) was observed at the treatment of the combination of 1mg/L ALG and 10mg/L HA. This study shows that the application of ALG and HA alone, and in combination, at low concentrations, increased the average number of PLBs and the amount of fresh weight, but shoot formation was higher at a high concentration compared with control.

scholarly journals DC GAS BREAKDOWN AND TOWNSEND DISCHARGE IN CO2

2020 ◽  
pp. 154-158
Author(s):  
V.A. Lisovskiy ◽  
S.V. Dudin ◽  
P.P. Platonov ◽  
V.D. Yegorenkov
Keyword(s):  
Carbon Dioxide ◽  
Breakdown Voltage ◽  
Electrode Distance ◽  
Zero Current ◽  
Dc Discharge ◽  
Current Voltage ◽  
Current Voltage Characteristics ◽  
Gas Breakdown ◽  
Townsend Discharge ◽  
Maximum Voltage

We report the breakdown curves and current-voltage characteristics (CVC) of the Townsend mode DC discharge we have measured in carbon dioxide. We compare the breakdown curves measured with two different techniques. With the first technique we regard as breakdown voltage the maximum voltage which we can apply across the electrodes without igniting the discharge with fixed values of the inter-electrode distance and the gas pressure. With the second technique we register the CVC of the Townsend mode in the μA-mA range and then extrapolate them to zero current. We reveal that in the nA-μA range the CVCs of the Townsend mode may have a complicated behavior due to the formation of the space charge. Therefore the second technique furnishes incorrect values of the breakdown voltage.

scholarly journals Effect of repeated electrical breakdowns on mineral and natural ester insulating oils

2021 ◽  
Vol 10 (6) ◽  
pp. 2989-2996
Author(s):  
Sharin Ab Ghani ◽  
Mohd Shahril Ahmad Khiar ◽  
Imran Sutan Chairul ◽  
Muhammad Imran Zamir
Keyword(s):  
Breakdown Voltage ◽  
Electrical Discharge ◽  
Electrical Breakdown ◽  
Standard Test ◽  
Test Method ◽  
Power Transformers ◽  
Insulating Oil ◽  
Different Types ◽  
Increasing Demand ◽  
Natural Ester

Transformer insulating oils are exposed to repeated electrical discharge or breakdowns inside power transformers. Durability tests are conducted to analyze the ability of oil to resist decomposition due to such high electrical stresses. With the increasing demand for alternative insulating oils for oil-immersed transformers, it is worthy to compare the performance of different types of insulating oils (conventional mineral-based insulating oil and natural ester-based insulating oil) under repeated electrical breakdown. In this paper, the AC breakdown voltage of different mineral-based and natural ester-based insulating oils is reported. Durability tests were conducted based on the AC breakdown voltage behavior of insulating oils after 50 electrical breakdown shots. The AC breakdown voltage of each insulating oil sample was assessed according to the ASTM D1816 standard test method. Based on the results, it can be concluded that the dissimilarity in chemical composition of the insulating oils has a significant effect on the AC breakdown voltage behavior of these oils under repeated electrical breakdowns.

scholarly journals Neuroprotective actions of 2,4-dinitrophenol: Friend or foe?

2007 ◽  
Vol 1 (4) ◽  
pp. 334-338 ◽  
Author(s):  
Sérgio Teixeira Ferreira ◽  
Fernanda Guarino De Felice
Keyword(s):  
Intracellular Signaling ◽  
Biological Activities ◽  
Mitochondrial Oxidative Phosphorylation ◽  
Therapeutic Approaches ◽  
Mitochondrial Uncoupling ◽  
Intracellular Signaling Pathways ◽  
Low Concentrations ◽  
Different Types ◽  
Neuroprotective Actions ◽  
High Concentrations

Abstract 2,4-dinitrophenol (DNP) has long been known to be toxic at high concentrations, an effect related to uncoupling of mitochondrial oxidative phosphorylation. Five years ago, however, we reported that low concentrations of DNP protect neurons against the toxicity of the amyloid-b peptide. Since then, a number of other studies have provided evidence of beneficial actions of DNP (at low concentrations), including neuroprotection against different types of insult, blockade of amyloid aggregation, stimulation of neurite outgrowth and neuronal differentiation, and even extension of lifespan in certain organisms. Some of these effects appear due to mild mitochondrial uncoupling and prevention of oxidative stress, whereas other actions are related to activation of additional intracellular signaling pathways. This study discusses the evidence supporting beneficial neuroprotective actions of DNP. DNP and other compounds with similar biological activities may be of interest in the development of novel therapeutic approaches for neurodegenerative diseases and other neurological disorders.

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