Abstract
The technique of the electric field distribution analysis in the 330 kV outdoor switch-gear is proposed. There are the zones in which electric field strength is greater than maximum permissible values by European Directive 2004/40/EU. The peak values of electric field strength are under the wires of A and C phases. These results are confirmed using programme package COMSOL. The electric field strength can be diminished to permissible values by shielding. It can be used as a shield comprised of some metal bars mounted parallel to wires of A and C phases over the shielding place. For the purpose of shielding it is sufficient to mount two bars provided they are mounted in the height of at least 2,4 m. Ill. 5, bibl. 4, tabl. 1 (in English; abstracts in English and Lithuanian). http://dx.doi.org/10.5755/j01.eee.112.6.435
Highlights
The Hygiene Norm HN110: 2001 "The electromagnetic field of industrial frequency in the workplace" is valid in Lithuania providing that the maximum allowable level of the electric field strength is dependent on the exposure time to this electric field
Particular safety measures are necessary to keep the electric field exposure to employees working both in the surroundings of the highvoltage transformer and at the 330 kV outdoor switch-gear, below the limit values indicated in the EU directive
There are potential employee exposure areas in the 330 kV outdoor switch-gear where electric field strength exceeds maximum limit values indicated in the EU directive 2004/40/EC
Summary
The Hygiene Norm HN110: 2001 "The electromagnetic field of industrial frequency in the workplace" is valid in Lithuania providing that the maximum allowable level of the electric field strength is dependent on the exposure time to this electric field. Phase wires represent the source of electric field at the outdoor switch-gear They are arranged at two different heights. Maximum values of the electric field strength can be evaluated through approximation of the power line by the straight wires without a sag, arranged at the height of the maximal wire sag In this case the field becomes two-dimensional and can be readily calculated. The electric field strength EMi (i=A, B, C) generated by the charge with density τi at the observation point M can be calculated using the equation as follows [3]. Results of simulation (see upper curve of the Fig. 3) were found to be close to the analytical results, the proposed methodology can be used for investigation the electric field which the three phase line creates
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