Field Test Results of Passive Loop for 154kV Overhead Transmission Lines for
Mitigation of Power Frequency Magnetic Field
(2013)Abstract
Power frequency magnetic field is still a critical problem for new construction of overhead
power transmission lines in Korea because most people have been concerned about possibly
carcinogenic effects of it. Although reference level of power frequency( 60Hz) magnetic field
has been set to 200uT in ICNIRP guidelines published in 2010, Korean government has no
intention of adjusting 83.3uT specified by law in 2006 to this new reference level in
consideration of people's concerns for the time being. Regardless of the current regulated
magnetic field value, electric utility company has been trying to reduce magnetic field in the
residential area in the vicinity of overhead power transmission lines to take into account of
public concerns on the long-term effect of magnetic fields. In an effort to reduce magnetic
field, engineering side has made considerable efforts to develop passive loop based, costeffective
mitigation technique of power frequency magnetic field almost for ten years. In
order to verify developed power frequency magnetic field mitigation technique based on
passive loop, a horizonal type of passive loop was designed and installed for commercially
operating 154kV overhead power transmission line for the first time in Korea. The
measurement results before and after the installation of passive loop showed that magnetic
field could be reduced to about 20%. It has been confirmed from the field test results that
passive loop could be commercially and cost-effectively utilized to mitigate power frequency
magnetic field, compared with other reduction methods, such as active loop, increase in
transmission line height, and power transmission using underground cables.
