Occupational exposure to extremely low-frequency magnetic fields near 20 kV, 3-phase shunt reactors at substations

Abstract

Directive 2013/35/EU of the European Parliament and Council, among other things, sets values for the occupational exposure of workers regarding the health and safety risks arising from electromagnetic fields. In order to ensure worker safety, the Finnish national grid operator, Fingrid Oyj, conducted several measurements of electromagnetic fields at its substations. One of the goals of the measurements was to ensure that a magnetic flux density of 1000 µT (rms), set as the lower action value by the EU directive, was not reached in any location accessible to substation workers. The highest magnetic flux densities at substations can be found near shunt reactors and their cables, which is why the measurements were focused on those areas. The lower action value of 1000 µT (rms) was surpassed at two locations. This discovery led to immediate actions to prevent workers from accessing these locations.