Frequency Dependence Of Electrical Parameters Research Articles

Modeling the Frequency Dependence of Electrical Parameters of Soil

An original semitheoretical causal model was developed to describe the frequency dependence of electrical parameters of soil in the representative frequency range of lightning currents. The expressions of such model, based simply on the measured low-frequency soil resistivity, can be promptly applied to general soils in practical problems. The model allows the user to adopt different levels of conservativeness to take the dispersion of the frequency dependence of soil and eventual uncertainties into account. The comparison of experimental results and those provided by this model denoted its consistency.

Lightning-Induced Voltages Over Lossy Ground: The Effect of Frequency Dependence of Electrical Parameters of Soil

The impact of the frequency dependence of soil resistivity and permittivity on lightning overvoltages induced on overhead lines over lossy ground is investigated. The Visacro-Alipio expressions were implemented on the hybrid electromagnetic model to take this effect into account. Systematic simulations were performed considering representative current waveforms of first and subsequent strokes and different stroke locations near the simulated overhead line. In general, the results indicated that this effect is responsible for a reduction of the induced overvoltage. This reduction increases with increasing soil resistivity and becomes relevant for soil resistivity above 1000 Ω·m.

New model for overhead lossy multiconductor transmission lines

A new model for time-domain electromagnetic transient analysis of overhead multiconductor transmission lines with frequency-dependent electrical parameters is presented. The model is based on the method of characteristics, which has been used before by means of the application of finite difference schemes. Conversely to the regular method of characteristics, the model presented here does not require the spatial discretisation along the line. Also, the frequency dependence of the electrical parameters is included by means of a transient resistance matrix. To validate the model, the results are compared to those from a frequency-domain method, the alternative transients program/electromagnetic transients program (ATP/EMTP) and the electromagnetic transients program-restructured version (EMTP-RV).

Dielectric and electrical properties of a tungsten bronze tantalate ceramic

Using high temperature solid state reaction the polycrystalline sample of K2Pb2Dy2W2Ti4Ta4O30 was prepared. Single-phase compound formation was confirmed by preliminary X-ray structural analysis. The surface morphology recorded by scanning electron microscope at room temperature exhibits a dense uniform grain distribution on the surface of the sample. Ferroelectricity in the material is confirmed by the variation of polarization with temperature. The temperature and frequency dependence of electrical parameters (impedance, modulus, conductivity, etc.) of the material exhibits a strong correlation with its microstructure (i.e., bulk, grain boundary, etc.) and electrical properties. A typical Arrhenius behavior was observed in the temperature dependence of dc conductivity. The nature of frequency dependence of ac conductivity obeys Jonscher's universal power law. The variation of current with temperature shows that the material has high pyroelectric coefficient and figure of merit, thus making it useful for pyroelectric sensors with working temperature upto 500 °C.

Effects of Additional Amount of Carbon Micro-Coils on the Electrical Properties of Carbon Micro-Coils Composite Sheet as a Tactile Sensor

The morphology and electrical properties, tactile sensing properties of carbon micro-coils (CMC) composite sheet were examined. Frequency dependence of electrical parameters; inductance (L), capacitance (C) and impedance (Z) were measured on single and double-helix composite sheets. It was found that these parameters of carbon micro-coils/polysilicone composites extensively changed with the additional amount of CMC with polysilicone resine. It was also observed that the higher additional amount (0 - 10 wt%) of CMC is appropriate for high sensitivity as a tactile sensor. DOI: http://dx.doi.org/10.3329/jbas.v36i2.12961 Journal of Bangladesh Academy of Sciences, Vol. 36, No. 2, 177-186, 2012

A Single-Probe On-Site Method of Measuring the Dielectric Constant And Conductivity of Soft Earth Media over a 1-GHz Bandwidth

A single-conductor transmission line inserted into the ground is used to measure the frequency-dependent dielectric constant and conductivity of soils and other soft earth media up to at least 1 GHz, as a function of depth. Wide band pulses are launched up the line from a transmitting stub at the tip, and a computer is used to Fourier transform the pulses received at the surface and compute the frequencydependent electrical parameters. If computer use is inconvenient, singlevalue measurements can be made directly from the received pulses.

Frequency Dependent Electrical Properties of Ferroelectric Ba0.8Sr0.2TiO3 Thin Film

The frequency dependent electrical parameters, such as impedance, electric modulus, dielectric constant and AC conductivity for ferroelectric Ba0.8Sr0.2TiO3 thin film have been investigated within the range of 1 Hz and 106 Hz at room temperature. Z* plane shows two regions corresponding to the bulk mechanism and the distribution of the grain boundaries-electrodes process. M" versus frequency plot reveals a relaxation peak, which is not observed in the ε″ plot and it has been found that this peak is a non-Debye-type. The frequency dependent conductivity plot shows three regions of conduction processes, i. e., a low-frequency region due to DC conduction, a mid-frequency region due to translational hopping motions and a high-frequency region due to localized hopping and/or reorientational motion.http://dx.doi.org/10.5755/j01.ms.17.2.490