scholarly journals Increasing the Accuracy of Measuring the Resistance of the Grounding System with an Electrodeless Method

2018 ◽  
Vol 7 (4.38) ◽  
pp. 379
Author(s):  
Maia Tugushi ◽  
Boris Karasiev ◽  
Gizo Partskhaladze ◽  
Madona Loria ◽  
Gocha Chavleshvili
Keyword(s):  
Measurement Error ◽  
Low Voltage ◽  
Sudden Change ◽  
Great Accuracy ◽  
Telecommunication Networks ◽  
Methodological Error ◽  
Industrial Enterprises ◽  
The Earth ◽  
Earth Electrode ◽  
Ground Loop

Recently, electrodeless methods of measuring the resistance of grounding devices have appeared, with the help of special clamps. But a large methodological error limits the possibility of their use, especially when rationing low resistances. The article shows the possibility to improve the accuracy of electrodeless measurement methods using commercially available measuring instruments.In electrical installations of telecommunication networks of buildings, structures and industrial enterprises, the form of the AC voltage signal of the industrial supply network (~220V, 50/60Hz) can be differ greatly from the sinusoidal for short periods of time. The causes of distortions are usually associated with a sudden change in the network load [1], for example, when you turn on a powerful electric motor, furnace, welding machine, etc.The occurrence of impulse overvoltages and interference caused by electromagnetic effects (lightning, switching, radio frequency and others) on low-voltage networks, not only leads to failure of electrical installations, cables, switchboards, but also to damage the terminal equipment and malfunction. This is due, primarily, to the saturation of modern buildings and structures with information, telecommunications and other digital equipment, which has a very low level of protection against impulse overvoltages and interference. All this makes it necessary to carry out appropriate protective measures. To reduce interference, it is necessary to perform a separate (working) ground loop, the resistance of which must be measured and periodically monitored.There are devices that allow an electrodeless method to monitor and evaluate the resistance of the ground loop. But these devices have a greater measurement error than devices that measure the resistance of the earth electrode method.The article deals with existing instruments (CA6410, MZC-303E) which can evaluate the resistance of the earth electrode and the possibility of increasing the accuracy of the measurement with the help of special current clamps is shown. Using a predetermined value of neutral impedance, the measurement error of the calculated resistance of the earthing switch can be determined with great accuracy. 

scholarly journals Relations Between Celestial and Selenocentric Reference Frames

1981 ◽  
Vol 63 ◽  
pp. 268-280
Author(s):  
J. Kovalevsky
Keyword(s):  
Reference Frames ◽  
Center Of Mass ◽  
Great Accuracy ◽  
Laser Ranging ◽  
Lunar Laser Ranging ◽  
Geometric Means ◽  
The Earth ◽  
Lunar Laser ◽  
Unique System ◽  
Different Types

AbstractThe very great accuracy with which the motions of the Moon can now be monitored by laser ranging, differential VLBI and occultation observations, implies that the interpretation of the measurements is conditioned by the choice and the accurate knowledge of a selenocentric, a terrestrial and a celestial frames. Two different types of selenocentric reference frames can be envisioned. The present selenographic frames are discussed but the author proposes that one should introduce a system defined by a purely geometric means. Some consequences of such a choice are discussed. One feature of the future conventional terrestrial frame is very important for Earth-Moon dynamics. Its origin should coincide with the center of mass of the Earth as determined by lunar laser ranging. As far as the quasi-inertial reference systems are concerned, the liaisons between a purely lunar dynamical system, subject to some hardly modelable effects, and purely celestial systems are analysed. The reduction of observations made with various techniques implies the use of different systems, and several problems are stated that should be solved before a unique system for Earth-Moon dynamics might be used.

scholarly journals DMF Data Format Usage for Change Detection

2012 ◽  
Vol 2012 ◽  
pp. 1-9
Author(s):  
Alejandro Cristo ◽  
David Valencia ◽  
Pablo J. Martínez ◽  
Rosa M. Pérez
Keyword(s):  
Remote Sensing ◽  
Data Structure ◽  
Data Fusion ◽  
Change Detection ◽  
Remote Sensing Data ◽  
Great Accuracy ◽  
New Techniques ◽  
Data Format ◽  
Specific Data ◽  
The Earth

Because of the availability of an overwhelming amount of remote sensing data obtained by different instruments, new techniques and applications have been developed in order to pursue the objective of detecting changes that occur in a particular area of the Earth or that affect a large part of the Earth. These studies have used datasets covering different wavelength ranges (visible, IR, radar, and so on), but common to all of them is the necessity for great accuracy to ensure that no bias is introduced due to data correction. Otherwise, a result may be the generation of false positives. Also, many studies have used several different datasets for the same area to detect changes (this is usually called data fusion), but there exists no specific data structure designed for this purpose. In this paper, we propose a data structure to be used for accurate change detection. This structure is transparent to the user and can be used for data fusion to improve those studies.

scholarly journals To the issue of assessing the efficiency of distributed generation in low-voltage electric networks

2020 ◽  
Vol 178 ◽  
pp. 01077
Author(s):  
A.N. Alyunov ◽  
A.Yu Belyanin ◽  
A.E. Nemirovsky ◽  
D.A. Zaripova
Keyword(s):  
Power System ◽  
Distributed Generation ◽  
Power Supply ◽  
Low Voltage ◽  
Electric Networks ◽  
Cost Of Electricity ◽  
Industrial Enterprises ◽  
Urgent Task ◽  
The Cost ◽  
Supply Systems

This article considers an urgent task of using autonomous sources for power supply systems of industrial enterprises of small and medium-sized production. The efficiency of choosing the time of their switching-on in peak hours of power system in order to reduce the cost of electricity is shown on the example of diesel generators.

On the mechanism of earthquakes

1964 ◽  
Vol 54 (5A) ◽  
pp. 1283-1289
Author(s):  
M. J. Randall
Keyword(s):  
Wave Equation ◽  
General Solution ◽  
Elastic Wave ◽  
Sudden Change ◽  
Elastic Equilibrium ◽  
Equilibrium Calculation ◽  
Elastic Wave Equation ◽  
The Earth ◽  
New Form ◽  
Elastostatic Problem

Abstract An earthquake may be regarded as resulting from a sudden change in the condition of elastic equilibrium in the Earth. A new form of the general solution of the elastic wave equation relates seismic radiation to displacement from equilibrium. Calculation of the radiation pattern for a proposed mechanism is thus reduced to an elastostatic problem.

A constraint on the earth's lateral heterogeneity from the scattering of spheroidal mode Q−1 measurements

1981 ◽  
Vol 71 (1) ◽  
pp. 183-197
Author(s):  
Norman H. Sleep ◽  
Robert J. Geller ◽  
Seth Stein
Keyword(s):  
Measurement Error ◽  
Elastic Properties ◽  
Normal Mode ◽  
Upper Bound ◽  
Probabilistic Analysis ◽  
Lateral Heterogeneity ◽  
Central Frequency ◽  
Data Set ◽  
Multiplet Splitting ◽  
The Earth

abstract We conduct a probabilistic analysis of the scattering of normal mode Q−1 measurements caused by the multiplet splitting from the earth's lateral heterogeneity. We apply our probabilistic results to a data set of unstacked Q−1 measurements for fundamental spheroidal modes from 0S13 through 0S28. Multiplet broadening of only 14 × 10−4 of the central frequency is sufficient to account for the scatter of the observed data. The observed scatter of Q−1 data is caused by a combination of three effects: lateral heterogeneity of density and velocities, actual lateral heterogeneity of Q−1 in the earth, and measurement error. The last two effects can only reduce the amount of lateral heterogeneity of density and velocities which is required to produce the observed scatter. Thus, by attributing the entire multiplet broadening to lateral heterogeneity of elastic properties, we can obtain an upper bound on its effect. It seems reasonable to assume that the maximum fraction of lateral heterogeneity in the mantle at the depths sampled by these modes (roughly from the surface to 1000 km deep) is on the same order (14 × 10−4) as the maximum multiplet broadening found by our analysis.

On the effects of a sudden change in the albedo of the Earth

1979 ◽  
Vol 60 (2) ◽  
pp. 505-511 ◽  
Author(s):  
Elizabeth J. Butler ◽  
Fred Hoyle
Keyword(s):  
Sudden Change ◽  
The Earth

Propagation Effectiveness Prediction and Simulation of VLF Communication

2013 ◽  
Vol 380-384 ◽  
pp. 3487-3492
Author(s):  
Guang Ming Li ◽  
Cui Hua Liu ◽  
Guang You Cai
Keyword(s):  
Wave Propagation ◽  
Radio Wave ◽  
System Performance ◽  
Waveguide Mode ◽  
Great Accuracy ◽  
Variable Parameters ◽  
The Earth ◽  
Effectiveness Prediction ◽  
Prediction And Simulation ◽  
Waveguide Problem

The vlf radio wave propagation is usually treated as a waveguide problem. It should be noted that many of the parameters that describe the boundaries of the earth-ionosphere waveguide are not known with great accuracy over all regions and times. In order to know the effect of underwater platform receiving in corresponding region and time, this paper makes use of the waveguide mode theory to predict the propagation effectiveness of vlf radio, offers the service of propagation environment for the system to adjust the variable parameters or abstain from propagation attenuation, makes the system performance matching the channel character and advancing the effects of vlf communication.

scholarly journals The Development of Spark Discharges in Hydrogen

1969 ◽  
Vol 22 (2) ◽  
pp. 155 ◽  
Author(s):  
MC Cavenor ◽  
J Meyer
Keyword(s):  
Glow Discharge ◽  
Low Voltage ◽  
Sudden Change ◽  
Coaxial Cable ◽  
Gas Temperature ◽  
Additional Information ◽  
Spark Discharges ◽  
Current Flows ◽  
Two Stages ◽  
Diffuse Glow

Streak photography has been used to supplement the earlier shutter photo. graphic investigation of Doran and Meyer (1967) using the same coaxial cable discharge circuit. Additional information has also been obtained from measurement of the potential distribution between the electrodes at two stages in the spark development. Redistribution of space charge is shown to give rise firstly to a transient diffuse glow discharge that has a close similarity with a normal d.c. glow discharge. It has also been shown that, even while the diffuse glow discharge expands, a partial constriction occurs in which most of the current flows along a narrow axial column. The resulting maximum in electron density eventually causes a rapid increase in dissociation of molecular hydrogen on the axis of the discharge brought about by a rise in the gas temperature. Owing to its greater electrical conductivity this axial column soon carries the entire current and the discharge becomes filamentary though still being maintained by a high cathode fall field, which exists until a sudden change in the cathode mechanism gives rise to the low voltage arc channel. Both the filamentary glow and arc columns are observed to expand according to an r cc ti law.

Sign in / Sign up

Export Citation Format

Share Document