Low-frequency grounding resistance and lightning protection

2010 ◽  
pp. 475-502 ◽  
Author(s):  
S. Visacro
Keyword(s):  
Low Frequency ◽  
Lightning Protection ◽  
Grounding Resistance

Time-Domain Analysis and Experimental Verification of Portable Grounding System’s TGR

2014 ◽  
Vol 705 ◽  
pp. 259-262
Author(s):  
Xin Bo Qu ◽  
Bi Hua Zhou ◽  
Ya Peng Fu ◽  
Li Juan Yang ◽  
Nan Zhang
Keyword(s):  
Time Domain ◽  
Time Domain Analysis ◽  
Frozen Soil ◽  
Lightning Protection ◽  
Grounding System ◽  
Grounding Resistance ◽  
Long Time ◽  
New Type ◽  
Set Up ◽  
Difference Time

The portable grounding system plays an important role in the lightning protection system of mobile equipments. But the traditional earth electrodes composed of vertical rods wouldn’t work well or would take a long time to set up in some conditions such as frozen soil, hard clay and so on. In this paper, a new type of portable grounding system which can be quickly spread and folded has been designed. To analyze the TGR’s (Transient Grounding Resistance) time-domain characteristics, the grounding systems have been modeled and simulated with FDTD (Finite Difference Time Domain). The influence rule of electrodes’ number and down-lead’s position to TGR has been studied with numerical analysis and validated with experiments. The results show that the new grounding system works well even on cement floor.

The Impedance Characteristics of ELF Line-Current Antenna over Inhomogeneous Anisotropic Ground

2014 ◽  
Vol 548-549 ◽  
pp. 771-775
Author(s):  
Chao Liu ◽  
Bing Wang ◽  
Hong Qiang Xu ◽  
Yun Long Liu
Keyword(s):  
Low Frequency ◽  
High Resistivity ◽  
Grounding Resistance ◽  
Extremely Low Frequency ◽  
Line Current ◽  
Impedance Characteristics ◽  
Proposed Model ◽  
Analytic Expression ◽  
Ground Conductivity ◽  
Important Purpose

The impedance of a horizontal Extremely low frequency (ELF) line-current antenna is studied. A new analytic expression for calculating a grounding resistance in any shape of ground screen in a two-layer earth is proposed, model adapted to a bed-rock with high resistivity. Its calculated accuracy has a significant improvement compared with previous literature. The radiation resistance of an ELF line-current antenna over inhomogeneous anisotropic ground is researched. The effect of anisotropy of the ground conductivity on radiation efficiency of an ELF line-current antenna is analyzed. The obtained results have important purpose in engineering design of ELF horizontal antenna path.

Simulation of Secondary Equipment Lightning Protection in EHV Substation Based on ATP

2014 ◽  
Vol 543-547 ◽  
pp. 514-517
Author(s):  
Hong Bo Li ◽  
Lin Niu ◽  
Nan Nan Gao ◽  
Jie Zhan ◽  
Pei Li ◽  
...  
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Lightning Protection ◽  
Earth System ◽  
Secondary System ◽  
Frequency Signal ◽  
High Frequency Signal ◽  
Lightning Current ◽  
Grounding Grids ◽  
The One

By analyzing the two lightning accidents happening to a 500kV substation situated in the lightning-prone northeastern Guangdong Province, I conclude as follows, there should be some problem in the equipotential earthing of the secondary system of this substation. Specifically, the existing potential difference in the secondary equipment gave rise to the meltdown of it which finally caused the accident. In the context,I build the one-point earthing parallel system simulation model according to ATP graphic pretreatment program, then by using slope-ramp simulation I study the lightning current which leaked into the grounding grids of the substation.In conclusion, the application of high frequency signal mixed low frequency signal earth system in the secondary system and the equipotential bonding is key to preventing accidents.

A Study on the Fine Structure of the Lateral Line Organ of the Sea Eel

1973 ◽  
Vol 31 ◽  
pp. 648-649
Author(s):  
K. Hama
Keyword(s):  
Fine Structure ◽  
Electron Microscope ◽  
Lateral Line ◽  
Low Frequency ◽  
Sensory Cells ◽  
Apical Surface ◽  
Voltage Electron ◽  
Sensory Epithelia ◽  
Low Frequency Vibration ◽  
Transmission Electron

The lateral line organs of the sea eel consist of canal and pit organs which are different in function. The former is a low frequency vibration detector whereas the latter functions as an ion receptor as well as a mechano receptor.The fine structure of the sensory epithelia of both organs were studied by means of ordinary transmission electron microscope, high voltage electron microscope and of surface scanning electron microscope.The sensory cells of the canal organ are polarized in front-caudal direction and those of the pit organ are polarized in dorso-ventral direction. The sensory epithelia of both organs have thinner surface coats compared to the surrounding ordinary epithelial cells, which have very thick fuzzy coatings on the apical surface.

Lectin Binding to Human Breast Tumor Cells

1976 ◽  
Vol 34 ◽  
pp. 34-35
Author(s):  
Robert E. Nordquist ◽  
J. Hill Anglin ◽  
Michael P. Lerner
Keyword(s):  
Carcinoma Cell ◽  
Ricinus Communis ◽  
Lectin Binding ◽  
Low Frequency ◽  
Breast Carcinoma Cell Line ◽  
Human Breast ◽  
Human Breast Tumor ◽  
Duct Carcinoma ◽  
Specific Antigens ◽  
Ricin Agglutinin

A human breast carcinoma cell line (BOT-2) was derived from an infiltrating duct carcinoma (1). These cells were shown to have antigens that selectively bound antibodies from breast cancer patient sera (2). Furthermore, these tumor specific antigens could be removed from the living cells by low frequency sonication and have been partially characterized (3). These proteins have been shown to be around 100,000 MW and contain approximately 6% hexose and hexosamines. However, only the hexosamines appear to be available for lectin binding. This study was designed to use Concanavalin A (Con A) and Ricinus Communis (Ricin) agglutinin for the topagraphical localization of D-mannopyranosyl or glucopyranosyl and D-galactopyranosyl or DN- acetyl glactopyranosyl configurations on BOT-2 cell surfaces.

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