scholarly journals Influence of DC Electric Fields on Pollution of HVDC Composite Insulator Short Samples with Different Environmental Parameters

Energies ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 2304 ◽  
Author(s):  
Xinhan Qiao ◽  
Zhijin Zhang ◽  
Xingliang Jiang ◽  
Tian Liang
Keyword(s):  
Power Systems ◽  
Electric Fields ◽  
Particle Motion ◽  
Particle Diameter ◽  
Environmental Parameters ◽  
Composite Insulator ◽  
High Voltage Direct Current ◽  
Electrical Stress ◽  
Motion Characteristics ◽  
Dc Electric Fields

Pollution-induced flashover is a serious threat to the safe operation of power systems. With the development of High Voltage Direct Current (HVDC), it is necessary to study insulator contamination in DC electric fields. In this paper, the energized wind tunnel contamination test was conducted in order to systematically study the pollution ratio, k (ratio of non-soluble deposit density (NSDD) of a DC-energized condition to a non-energized condition), under different environmental parameters. Later, a two-dimensional contamination model of short samples of an HVDC composite insulator was established. The particle motion characteristics under different environmental parameters were then analyzed by the finite element method (FEM). The research results showed that—the DC electric field had an influence on particle motion but in different environments, the degree of influence was different. In addition, k was found to largely vary, with a variation in the environmental parameters. When the electrical stress (Es) increased from 0 to 70 kV/m, k increased gradually. However, when the wind speed (ws) increased, k experienced a decreasing trend. Finally, as the particle diameter (dp) decreased, k increased at first, followed by a decrease, and then again showed an increase. The results of the pollution ratio, k, for different environmental parameters are of great importance for guiding anti-pollution work in power systems.

Convergence effect of droplet coalescence under AC and pulsed DC electric fields

2021 ◽  
pp. 103776
Author(s):  
Xin Huang ◽  
Limin He ◽  
Xiaoming Luo ◽  
Ke Xu ◽  
Yuling Lü ◽  
...  
Keyword(s):  
Electric Fields ◽  
Droplet Coalescence ◽  
Pulsed Dc ◽  
Dc Electric Fields

Pulsed DC electric fields couple to natural NAD(P)H oscillations in HT-1080 fibrosarcoma cells

2001 ◽  
Vol 114 (8) ◽  
pp. 1515-1520 ◽  
Author(s):  
A.J. Rosenspire ◽  
A.L. Kindzelskii ◽  
H.R. Petty
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Cell Function ◽  
Low Frequency ◽  
Reactive Oxygen Metabolites ◽  
Pulsed Dc ◽  
Fibrosarcoma Cells ◽  
Chemotactic Factors ◽  
Oxygen Metabolites ◽  
Dc Electric Fields

Previously, we have demonstrated that NAD(P)H levels in neutrophils and macrophages are oscillatory. We have also found that weak ultra low frequency AC or pulsed DC electric fields can resonate with, and increase the amplitude of, NAD(P)H oscillations in these cells. For these cells, increased NAD(P)H amplitudes directly signal changes in behavior in the absence of cytokines or chemotactic factors. Here, we have studied the effect of pulsed DC electric fields on HT-1080 fibrosarcoma cells. As in neutrophils and macrophages, NAD(P)H levels oscillate. We find that weak (~10(-)(5) V/m), but properly phased DC (pulsed) electric fields, resonate with NAD(P)H oscillations in polarized and migratory, but not spherical, HT-1080 cells. In this instance, electric field resonance signals an increase in HT-1080 pericellular proteolytic activity. Electric field resonance also triggers an immediate increase in the production of reactive oxygen metabolites. Under resonance conditions, we find evidence of DNA damage in HT-1080 cells in as little as 5 minutes. Thus the ability of external electric fields to effect cell function and physiology by acting on NAD(P)H oscillations is not restricted to cells of the hematopoietic lineage, but may be a universal property of many, if not all polarized and migratory eukaryotic cells.

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