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In this paper, a new type of portable horizontal grid earth electrode has been designed for mobile equipments. With FDTD method and the impulse ground measurement system, different number of earth electrodes' responses to double exponential pulse current have been tested on grassplot. After filtering and calculating, the curve of Transient Grounding Resistance (TGR) in time domain can be gotten. The...
Lightning fields are commonly obtained by integrating the output of antennas that produce replicas of the derivatives of the wanted quantities. The integration is carried out using RC integral circuits that introduce a distortion in the form of a decay time constant that may affect the response of the LEMP electric field sensor. As the decay time constant demonstrate different feature of the electric...
According to the existing non-orthogonal error of lightning electromagnetic pulse (LEMP) magnetic field measurement device, the paper derives theoretical and actual output voltage of antennas induced by the alternating magnetic flux, which are generated by the current-carrying loop antenna injected with sine wave, gets the orthogonal extent and corrects the non-orthogonality of the device through...
In many electrical and electronic systems, metallic enclosures are used to provide electromagnetic shielding. These enclosures normally contain thin wires, thin slots, and frequency-selective slots that degrade the shielding effects. The capacitance thin-slot formalism (C-TSF) by [2] has been around for quite some time in the finite-difference time-domain analysis (FDTD) of thin-slot penetration....
In this paper, the model of six-degree-of-freedom electromagnetic tracking system is introduced. To promote the precision and stability of calculating an object's parameters, a new improved arithmetic is presented, which is a combination of the maximal ponderance of unit pointing vector tracking arithmetic and the eigenvector arithmetic. The correction is validated by the numerical simulation results...
To simulate the EMP propagation in large-scale and long-distances vaulted tunnel, an effective MW-FDTD method based on parallel computing was presented. The convolution PML (CPML) is adopted to truncate the computation domain, which reduces the reflection error greatly. The accuracy and the efficiency of the proposed method have been verified by comparing the results of the parallel FDTD algorithm...
In this paper, a new rectangular enclosure model for shielding effectiveness (SE) is established, which is in more accordant with practical engineering environment for it considered the ground reflection. The SE is analyzed by using different thin-slot formalism methods and the results given by C-TSF, ETSF and CP are compared with results of the finer resolution. When the width of the slot is comparable...
In this paper, a perfectly matched layer (PML) implementation for an unconditionally stable finite-difference time-domain scheme based on weighted Laguerre polynomials(WLP-FDTD) in cylindrical coordinates is presented. A numerical example is introduced to validate the proposed formulations.
The shielding effectiveness of conductive cement-based materials to HEMP is analyzed using theoretical method when the materials' conductivity range 10-3~10 S/m. The threshold of materials' conductivity is achieved when their shielding effectiveness increases suddenly. Furthermore, the effect of monolayer and double layer conductive cement shielding rooms on shielding effectiveness to HEMP is discussed...
This work aims at studying detailed design of the transient grounding test system based on the experiment. The influence of some factors on transient grounding test is experimented. Finally, some valuable advice about detailed design of the transient grounding test system is given.
The shielding effectiveness of conductive cement-based materials to HEMP is analyzed using theoretical and FDTD method when the materials' conductivity range 10-3~102 S/m. The effect of materials' conductivity on shielding effectiveness to HEMP is obtained and the threshold of materials' conductivity is achieved when their shielding effectiveness increases suddenly. Finally, the experimental shielding...
The characteristics of transient voltage, current and grounding resistance of two kinds of radialized grounding electrodes were investigated based on field measurements. Each kind of grounding electrode was made of reinforcing steel bars with diameter of 10 mm, and had the same total length of 16 m, and were buried horizontally at the depth of 0.6 m from the ground surface. The star-shape grounding...
The characteristics of transient voltage, current and grounding resistance of a spokewise grounding electrode is investigated based on field measurements. The grounding electrode is composed of 8 reinforcing steel bars with diameter of 10 mm, every bar with the length of 2 m, and is buried at the depth of 0. 6 m from the ground surface. A pulse discharge from a high-voltage capacitor is applied at...
Electromagnetic shielding is the technique that reduces and prevents coupling of undesired radiated electromagnetic energy into equipment, so as to enable it to operate compatibly in its electromagnetic environment. Usually, the frequency considered for electromagnetic shielding design is above 10 kHz, but the lower frequency for some special demand is 50 Hz or even 0.01 Hz sometimes. This paper mainly...
In this paper, electric field near ground during thunderstorm process is discussed with field data measured by thunderstorm electric field mill and numerical simulation. The measured field data shows that the atmospheric field became strong as measure height increased. The cause is given out by the numerical simulation. And the result of numerical simulation shows accordance with measured data. The...
The proposed DF-FDTD method can be used to build a model for the transfer impedance. According to this transfer impedance model and the induced current of the outer conductor, the induced current and voltage of the inner conductor can be obtained by the transmission line (TL) model. This work can provide the theory support for the protection of the inner conductor from the EMP field.
This paper discussed the influence of the parameters of the transient grounding model on numerical analysis using FDTD method; some useful results are given and verified by the experiment.
This paper presents the measurements of shielding effectiveness of reinforcing bar loops (RBL) and reinforcing bar cage (RBC) to magnetic field. A testing method was applied to measure the shielding effectiveness of RBL and RBC with its joints wired or welded. The signals in this experiment are continuous wave with frequency of 14 kHz, 100 kHz and 200 kHz. The variation of the shielding effectiveness...
A three-dimensional (3-D) sensor is proposed for transient electric field measurements in this paper. Three direction components of total fields can be measured simultaneously by using 3-D sensor. The 3-D antenna can convert fields to induced voltages, and the optical transmitter can transform electricity signals to light signals. In order to validate the antenna' s configuration, numerical simulation...
In this paper, a new scheme of circuits to an electromagnetic sensitivity system is designed. The system is to be used in stimulant training equipments. Through the test of experiments, it can be seen that the results of experiments agree with the theory, so the scheme is reliable and desirable. The maximum distance of measuring is 150 cm. The measuring error of distance is less than 1.5 cm and the...
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