Transmission Line Magnetic Fields Research Articles

An energy-efficient CMOS interface circuit with maximum power point tracking and power management capabilities for self-powered sensor node applications using 50/60 Hz transmission line magnetic field harvesters

An energy-efficient CMOS interface circuit with maximum power point tracking and power management capabilities for self-powered sensor node applications using 50/60 Hz transmission line magnetic field harvesters

Computation of transmission line magnetic field harmonics

AbstractThis work presents an accurate procedure to evaluate low‐frequency magnetic fields produced by overhead power line distorted currents containing several harmonic orders. The analysis is conducted in the framework of quasi‐stationary regimes where wave‐propagation phenomena are of little relevance. Bearing in mind that international regulations for safe public exposure to electromagnetic fields establish increasingly stringent reference levels for the magnetic‐field intensity as the frequency increases, the key issue addressed here is whether the presence of higher order harmonics may cause those reference levels to be exceeded. Complying with standard power quality requirements, our analysis considers that the harmonics have prescribed small magnitudes. Computation examples, including balanced and non‐balanced loads, are presented. It is shown that the worst‐case scenario corresponds to the injection of harmonics produced by balanced loads whose order is a multiple of three. Copyright © 2006 John Wiley & Sons, Ltd.

The soil aggregate stability under the energy transmission line magnetic field

In recent years, there has been increasing interest in finding effects of magnetic fields on soil properties. Some minerals presents in soil have magnetic susceptibilities. In this case, it is expected that physical and chemical properties of soil can be affected by magnetic fields. In this research, the effects of magnetic field on aggregate stability of the soil in Isparta- Kuleönü, Turkey, were studied. The research area was intersected by the energy transmission line (ETL) of 154 kV (50 Hz), on a clay loam soil (Vertic Haploxeroll). Soil samples were taken from 0–15 cm layers at gradually increased distances in relation to ETL. The changes in dispersion ratio, aggregate stability and mean weighed diameter (MWD) were measured. Magnetic field densities (MFD) at adjacent distances to ETL were much higher than those other distances. The average dispersion ratio, aggregate stability and MWD values at perpendicular direction to ETL ranged from 16.65±1.46 % to 25.24±1.03 %, from 32.64±3.36 % to 48.19±3.40 %, and from 0.39±0.01 mm to 0.68±0.06 mm, respectively. The data obtained for stability parameters were in accordance with each other, and indicated a relatively low relationship between MFD and stability parameters.

The Influence of Conductor Sag on Spatial Distribution of Transmission Line Magnetic Field

Conunon methods for the calculation of electric fields created by power transmission lines assume straight lines parallel to a flat ground and the influence of the sag due to the line weight is neglected. In this paper the magnetic fields of a catenary 3-Phase line that has a change in direction was calculated and discussed. It is believed that this work has not been published before.

Principles in transmission line magnetic field reduction

The basic principles of transmission line magnetic field generation are addressed in order to enhance understanding when designing for low fields. For structured analysis, the B-field RMS-value is represented as a product of autonomous factors. The range of applicability spans phase-split arrangements, active shielding by impressed shield currents, and passive shielding using induced currents with and without series compensation of the shield-conductor loop. An innovative four-conductor scheme is presented.

96/03167 - Determining EHV transmission line magnetic fields by applying the vector magnetic potential concept

96/03167 - Determining EHV transmission line magnetic fields by applying the vector magnetic potential concept

Determining EHV transmission line magnetic fields by applying the vector magnetic potential concept

These days renewed attention is being given to the biological effects of non-ionizing radiations from the power frequency electromagnetic fields of extra-high-voltage (EHV) transmission lines. Prior to fixing limits about the safe levels of human exposure to such radiation, it is essential to determine its field magnitudes. In this paper the concept of vector magnetic potential has been extended for a multiphase multiconductor transmission line and expressions for the flux densities of the resulting magnetic field components have been developed. This approach for determining the transmission line magnetic fields quantitatively is new and straightforward. It requires only easy-to-obtain physical parameters having specific values and involves no uncertainty. The proposed approach was applied to determine the magnetic field distribution within and beyond the rights of way of five transmission systems at 132, 230, 345, 500 and 765 kV. The results obtained were in close agreement with the measured field values. The proposed approach is expected to be useful for transmission line designers as a convincing and fast analytical tool for designing the allowable line current magnitude, conductor height and spacings, and number of circuits in order to result in a prespecified magnetic field. However, the results reported herein are expected to benefit researchers engaged in assessing whether magnetic fields of the orders of magnitude obtained for various transmission systems can have any adverse effects on the health of living beings exposed to the lines.

Series-capacitor compensated shield scheme for enhanced mitigation of transmission line magnetic fields

A new magnetic field mitigation concept involving a series-compensated shield circuit paralleling a transmission line between the line and the right-of-way edge is presented. An evaluation methodology is proposed which is valid for analyzing magnetic field mitigation concepts in general. The research discussed identifies the shield circuit and compensation requirements and shows the effectiveness of the scheme. Practical implementation considerations are included. >

Magnetic coupling to a prolate spheroid model of man

Calculations are given for the induced current density and power absorbed by a prolate spheroid model of a man when exposed to transmission line magnetic fields. The spheroid model can be expected to provide values of the right order of magnitude. Biological hazards from exposure to magnetic fields are considered.