Patent Number: 059862769
Section: summary

BACKGROUND OF THE INVENTION Field of the Invention The present invention relates generally to electric power systems and electrostatic and electromagnetic fields associated with high voltage fields; more particularly the invention relates to X-ray radiation in such fields, which is suspect in the etiology of leukemia and other forms of cancer. Health hazards to persons from prolonged exposure to such fields are eliminated by preventive systems and equipment shielding according to the invention. For several years studies have indicated a strong statistical relation between various childhood cancers and proximity of persons to high tension power lines. A Johns Hopkins University study by S. J. London et al. showed an especially high correlation of cancers to extremely high voltage lines. This study was done by comparing the utility power configurations associated with childhood leukemia with a random sampling of people in the Los Angeles area. It showed two to three times higher occurrence of high power lines in the vicinity of the leukemia patients than for the general public. Other studies have shown an occurrence of breast cancer in male power line workers approximately four times that of the general public. Because of such studies, power companies have been attempting to ascertain a causal relation between the presence of power lines and the health effects. When the locations studied in the Johns Hopkins University study were checked for electric field strength--i.e., electric and magnetic fields, no correlation was found. Despite the lack of correlation to electric field strength or magnetic field strength, reduction of these fields has been the primary focus of the power companies, for lack of more definitive approaches. Certain relevant technical aspects are well known in the art. The electric field surrounding a low frequency conductor is approximately perpendicular to the surface of the conductor, as with power lines with corona discharge, and field strength increases near small radii. The equipotential lines are parallel to the conductor and the gradient is perpendicular to the surface in the vicinity of the surface. The wavelength at 60 Hz is sufficiently long with respect to the ionization zone around the conductor to ignore the component in the direction of the conductor. The high electric field provides the energy to accelerate the free electrons to sufficient energy levels to generate X-rays. Soft X-ray levels are only 2-10 times the energy of hard ultraviolet UV, and continue up from there. Extraneous electric and magnetic fields, which were thought to be a health risk associated with electric power transmission, were avoided in the prior art by using various cable and wiring arrangements, particularly coaxial transmission lines configured so that return current flows in the outer conductors in a bi-polar field-cancelling mode particularly suited to reducing electromagnetic fields. See U.S. Pat. No. 5,218,507 to Ashley, June 1993. However, little attention has been given to X-rays caused by high voltage fields accelerating electrons in coronas. It has been believed that X-rays produced thereby are too soft to be of concern. Recently, there have been statistical studies of correlations of cancer cases with the possibility of X-ray generation in power plants in the vicinity of patients' normal activity. See IEEE Transactions on Broadcasting, Vol. 36, No. 1, March 1990. BRIEF SUMMARY OF THE INVENTION Recent research indicates a plausible cause and effect relationship between ionizing radiation and cancer effects. The electrical and magnetic fields emanating from 60 Hz power lines are nowhere near the energy bands that should produce ionizing radiation. Therefore, high voltage discharge corona effects appear to be a possible cause of X-ray generation. X-rays for common medical imaging are in the 20 keV (20 kilovolt electron) energy band. The energy released when an electron drifts in vacuum, through a 20,000 volt field, gaining kinetic energy, and impinging on an appropriate target, converts kinetic energy to energetic photons, producing X-rays. An electron drifting through the same field in air would normally encounter a significant number of air molecules which, because of impacts, would slow the electrons down and prevent sufficient kinetic energy to produce X-rays. As the electric field strength increases, however, the distance necessary to travel to gain the same kinetic energy decreases. This increases the chance that an electron will gain the energy necessary to produce an X-ray when it impacts a target. The target material also affects the generation of X-rays, the efficiency increasing rapidly with increasing atomic number (Z) of the target. High tension power lines produce extremely high local fields. In places, these are higher than the 20 kilovolts/inch necessary to ionize the air. The corona thus produced is visible as a slight glowing, under proper conditions, or may be heard as crackling on a radio when passing near high tension power lines. A strong discharge may even be audible in the proximity of high tension lines, but not all of this is corona, because some arcing also occurs due to surface contamination of the insulators and faulty insulators. In accordance with the invention, the electric field strength may be reduced by several means and the target material may be changed. Providing such means and modifications are objects of the instant invention. A primary object of the invention is to reduce quantity and energy of X-rays generated by high voltage apparatus, by use of low atomic number materials as corona discharge targets. The materials being conductive, insulating, or semiconductive, are used to coat, cover, or sheath high voltage transmission lines and components. An object of the invention is to use such materials to coat or form the discharge points of high voltage devices, including lightning rods, high voltage contacts, switches and relays, and to use these materials (semiconductive or conductive) to form a coating material capable of covering rough/pointed areas including junctions and hardware to further reduce X-ray generation by reducing arcing. This increases the effective radius of the conductor to reduce the electric field strength and reduce target efficiency. Additionally, shielding may be employed against X-rays emitted from high voltage switches, relays, and interconnects. Another object of the invention is to provide a method and means for remote sensing of ionizing radiation, including instrumentation to detect and measure, combined with a transponder to report arcing in power equipment, including poles and tower installations. The detection methods include ultrasonics, X-ray, and radio frequency emissions monitoring.