Power Line Environment Research Articles

Magnetic field-induced currents in the human body in proximity of power lines

Electric currents induced due to 60 Hz magnetic fields in a human body placed in close proximity to various high voltage transmission lines are computed. A realistic model of the human body from the anatomical and electrical point of view with resolution of 1.3 cm for the body and 0.665 cm for the head is used. The computations are performed using the impedance method. Three representative configurations of high voltage transmission lines, namely 500 kV, 138 kV and 25 kV are analyzed. The results indicate that the maximum current densities of the order of 0.2 /spl mu/A/cm/sup 2/ can be induced in a lineman working on a 500 kV line (0.5 m away from closest conductors). A good correlation can be seen between the computed magnetic field in the location of the human body and the induced current densities. The induced currents computed here and estimated from measured magnetic fields in various power line environments are compared to those for typical home and office exposures, including appliances.

Object oriented expert system estimates line ampacity

In a competitive power supply business environment, line ampacity predictions are required by electric power utilities for economic generation planning, system dispatching, contingency planning, security analysis, and for normal and emergency operation of electric power systems. The line ampacity system featured in this article calculates ampacity from general purpose National Weather Service (NWS) forecasts and does not require additional hardware on power lines. By designing the ampacity expert system with objects and rules, it can be easily implemented in small and large electric companies. The Line Ampacity System (LINEAMPS) is a PC/Windows-based, power-line ampacity, expert-system program for the estimation of line ampacity during steady-state, dynamic state, and transient conditions. It was developed by the application of artificial intelligence using object-oriented, knowledge-base design of the power line environment. The expert system provides hourly values of line ampacity up to 7 days in advance and is used for the operation, planning, and design of transmission and distribution lines at all voltages. >

1980 Prize Paper Environmental Considerations Concerning the Biological Effects of Power Frequency (50 or 60 Hz) Electric Fields

The results of a comprehensive literature survey on the biological effects of 60 Hz electric fields are summarized to describe two contrasting sets of research findings. On one hand, research results in Western Europe and America have failed to provide any evidence that human exposure to present levels of fields from high voltage overhead power lines, as normally encountered, has any harmful biological effect. On the other hand, studies performed in the USSR report some undesirable effects on workers--not in the typical power line environment--but in the more complex environments found in high voltage switchyards. The disparity in results could be attributed to differences between the environments found near high voltage lines and within switchyards. Special measurements ments of the low-frequency acoustical noise in a high voltage switchyard disclosed a high level (104 dB) of 120 Hz sound. This high intensity, 100 or 120 Hz sound, found in switchyards (but not near transmission lines) could produce symptoms similar to those reported for Soviet switchyard workers. Other possible biologically significant environmental influences include repeated spark discharges and the chemical environment. Numerous studies have similarly neglected the total environment and examples are presented in this paper. This neglect presents a major obstacle in trying to use the results of these studies.

Environmental Considerations Concering The Biological Effects of Power Frequency (50 or 60 Hz) Electric Fields

The results of a comprehensive literature survey on the biological effects of 60 Hz electric fields are summarized to describe two contrasting sets of research findings. On one hand, research results in Western Europe and America have failed to provide any evidence that human exposure to present levels of fields from high voltage overhead power lines, as normally encountered, has any harmful biological effect. On the other hand, studies performed in the USSR report some undesirable effects on workers--not in the typical power line environment--but in the more complex environments found in high voltage switchyards.

Power Line Communication an Essential Tool for Digital Bangladesh

An estimation for the power line communications (PLC) for Bangladesh is made referring various technical research papers and current Journals. The aim of this study is to identify essential aspect of the power line communications for both domestic and outdoor application and the use of consumer communication when various possible services are developed worldwide commercially [1,9]. Possible services, bandwidth, service area, quality, reliability, and the cost are also taken into considerations. The signal in a transmission line is impaired by the presence of unwanted extraneous signals (noise and interference) on the line. The frequency dependent characteristics of the transmission line are also responsible to impair the transmission of signals along the lines. Noise and interference, with its presence tends to impede the reception of the desired signal and is usually the limiting factor in its detection. Noise is usually composed of randomly occurring voltages, which are unrelated in phase or frequency and may sometimes be of a very peak in nature. Interference on the other hand is usually more structured than noise since it arises as unwanted coupling from just a few signals in the network. In this paper a brief discussion of noise in a power line environment and need for power line communication in Bangladesh is presented as an essential tool for digital Bangladesh. KEY WORDS: Cyclostationary noise; Attenuation; PDF(probability density function); White noise; Interference; Variance DOI: http://dx.doi.org/10.3329/mist.v3i0.8047