scholarly journals Accelerated Charge Dissipation by Gas-Phase Fluorination on Nomex Paper

2019 ◽  
Vol 9 (18) ◽  
pp. 3879
Author(s):  
Feipeng Wang ◽  
Li He ◽  
Muhammad Zeeshan Khan ◽  
Tao Zhang ◽  
Qi Zhao ◽  
...  
Keyword(s):  
Space Charge ◽  
Surface Charge ◽  
Gas Phase ◽  
Chain Scission ◽  
Decay Rates ◽  
Electron Trap ◽  
Insulation System ◽  
Charge Decay ◽  
Charge Characteristic ◽  
Potential Decay

The surface charge and space charge accumulation in paper used in oil–paper insulation system may distort electric field distribution and lead to the flashover and breakdown of insulation system. In this paper, the effect of gas-phase fluorination on the surface charge and space charge characteristics of oil-impregnated Nomex paper was investigated. Nomex T410 was fluorinated at 25 °C using F2/N2 mixtures with 20% F2 in volume at 0.05 MPa for 15, 30 and 45 min. Fourier Transform Infrared Spectroscopy (FTIR) proved that the molecular chain scission and cleavage occurred during gas-phase fluorination. Furthermore, the surface charge and space charge characteristic of the original and fluorinated oil-impregnated paper were measured using an electrostatic voltmeter and Pulsed Electroacoustic (PEA) equipment respectively. Furthermore, the hole and electron trap distribution of the samples were obtained by Isothermal Surface Potential Decay (ISPD) model. The results showed that both the positive and negative charge decay rates were accelerated by gas-phase fluorination and the hole, electron trap energy and density of the fluorinated samples were reduced by fluorination. It is suggested that the space charge dissipation was also accelerated by fluorination, indicating that gas-phase fluorination is an effective approach to modify the charge dynamics of oil-impregnated Nomex paper.

scholarly journals Surface potential decay on silicon rubber samples at reduced gas pressure

2018 ◽  
Author(s):  
Shahid Alam ◽  
Yuriy V. Serdyuk ◽  
Stanislaw Gubanski
Keyword(s):  
Space Charge ◽  
Surface Potential ◽  
Solid Material ◽  
Ambient Air ◽  
Surface Charges ◽  
Inherent Feature ◽  
Charge Decay ◽  
Gaseous Media ◽  
Potential Decay ◽  
Surface Leakage

<p>Accumulation of interfacial charges is an inherent feature of HVDC insulation based on solid and gaseous media. The collected surface charges can alter the geometrical electric field leading to undesirable phenomena such as partial discharges and even unexpected flashovers. <br />In the present paper, surface potential decay on silicone rubber samples is analyzed at reduced pressures of ambient air that allows for elimination of surface charge neutralization by gas ions. Thus, influences imposed by bulk and surface conduction in the solid material are studied by means of computer simulations and experimental measurements. The results allow for identifying levels of bulk and surface conductivities above which the corresponding charge decay mechanism becomes dominant. It is shown that with a negligible space charge effect and significant surface leakage, there exists a notable spread of charge along gas-solid interface yielding visible crossover phenomenon in charge decay characteristics. It is also demonstrated that the effect of space charge in the material bulk on surface potential decay can only be significant within layers of material finer than ca. 100 μm.</p>

scholarly journals Influence of surface charge decay on cavity PD frequency at DC voltage

2019 ◽  
Vol 13 (2) ◽  
pp. 193-200 ◽  
Author(s):  
Cheng Pan ◽  
Wenbin Song ◽  
Ju Tang ◽  
Yi Luo ◽  
Jia Yin
Keyword(s):  
Surface Charge ◽  
Dc Voltage ◽  
Charge Decay

scholarly journals Effect of Graphene Coating on Space Charge Characteristic of XLPE and Semiconductive Layer at Different Temperatures

IEEE Access ◽  
2019 ◽  
Vol 7 ◽  
pp. 124540-124547 ◽  
Author(s):  
Zhipeng Lei ◽  
Davide Fabiani ◽  
Chuanyang Li ◽  
Simone Vincenzo Suraci ◽  
Giacomo Selleri ◽  
...  
Keyword(s):  
Space Charge ◽  
Graphene Coating ◽  
Different Temperatures ◽  
Charge Characteristic

Surface charge decay of epoxy resin treated by AP-DBD deposition and direct fluorination

2019 ◽  
Vol 26 (3) ◽  
pp. 768-775
Author(s):  
Cheng Zhang ◽  
Yiyang Ma ◽  
Fei Kong ◽  
Ruixue Wang ◽  
Chengyan Ren ◽  
...  
Keyword(s):  
Surface Charge ◽  
Epoxy Resin ◽  
Direct Fluorination ◽  
Charge Decay

Surface charge decay on HVDC insulators: Temperature and Field effects

2013 ◽  
Author(s):  
R. Gremaud ◽  
M. Bjelogrlic ◽  
M. Schneider ◽  
E. Logakis ◽  
Ch. Schlegel ◽  
...  
Keyword(s):  
Surface Charge ◽  
Field Effects ◽  
Charge Decay

Blast-wave propagation in a spray

1978 ◽  
Vol 88 (4) ◽  
pp. 641-657 ◽  
Author(s):  
T. H. Pierce
Keyword(s):  
Gas Phase ◽  
Blast Wave ◽  
Wave Structure ◽  
Blast Waves ◽  
Decay Rates ◽  
Liquid Droplets ◽  
Two Phase ◽  
Number Range ◽  
Reactive Liquid ◽  
Particle Velocities

A first-order analysis is presented for the propagation of a blast wave through a dilute spray of non-reactive liquid droplets that are suspended in a non-reactive gas-phase carrier. The analysis permits straightforward computation of decay rates and internal wave structure for wave strengths in the approximate Mach number range 4 ≤ Ms ≤ 15, and loading factors (mass of spray per unit mass of carrier) less than about 0·4. The droplets must be sufficiently small to completely change phase in a distance behind the shock that is at all times negligible compared with the wave radius. Representative calculations are presented and discussed. These show more rapid decay rates and higher pressures, densities, and particle velocities in two-phase blast waves when compared against equivalent gas-phase blast waves. A simplification of the analysis for the regime of higher wave Mach numbers (strong waves) is also given, which for that case allows direct algebraic calculation of early wave characteristics.

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