Currently, 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. The exposure to the electric field of industrial frequency with the strength of 5 kV/m for the entire working day is unallowable, whereas the short-time exposure to the electric field with the strength exceeding as much as 20 kV/m is allowed. However, in 2012 the EU Directive 2004/40/EC [1] will come into effect in Lithuania. This Directive prohibits even a short-term exposure to electric field of industrial frequency 50 Hz with the effective strength value exceeding 10kV/m. According to the research, the findings and results of which have been discussed [2], surroundings of the 330 kV overhead power-line include some areas that are hazardous to humans with the electric field values exceeding limits set out in the EU Directive. The situation in the 330 kV outdoor switch-gear might turn out to be even more hazardous as phase wires are at a lower height here. Consequently, particular safety measures are necessary to keep the electric field exposure to employees working both in the surroundings of the high-voltage transformer and at the 330 kV outdoor switch-gear, below the limit values indicated in the EU directive. This research paper involves analytical and simulating investigation of the electric field distribution at the 330 kV switch-gear, identification of areas hazardous to humans, discussion of safety measures used to diminish electric field to the permissible limit values, as well as research into their effectiveness.
展开▼
