The line is located in the open, without natural protection, exposed to frequent lightning impacts, and is characterized by high frequency of non-steady lightning outages.The line was built in an area characterized by high lightning density, absence of natural shielding and high soil resistivity. Not surprising, that it was exposed to outages resulted by lightning impacts. The lightning protection means previously deployed in power lines were II class metal oxide arresters (MOA). MOAs are effective with low earthing resistance.Their application with high earthing resistance (>15Ω) entails premature aging, high maintenance costs and reduced reliability of all power grid.

    Poles are located in high soil resistivity area (top/middle layer > 200 Ωm) with earthing resistance > 15 Ω.

    In June 2016, 33 kV distribution line was equipped with SAdM35z LLPDs and fault indicators under Lodestar brand (designed by A-TREE Research & Development Company Ltd.). For 10 months of line performance monitoring, from June 2016 to March 2017, the faults number was compared with the data on storm activity in the vicinity of the considered distribution line.

    According to the line lightning performance analysis, prior to SAd35z installation, from January 2015 to May 2016 the line have been tripped 22 times. After SAd35z installation, from June 2016 to March 2017, there were only 3 outages. Therefore, SAd35z installation resulted in 86% reduction of lightning outages.

    Cost of replacing prematurely-aged components of MOV arresters installed in areas with high soil resistivity decreased more than 10 times after SAdM35z application.

    TNB recognized the results of the pilot project as positive and is planning large-scale SAd35z installation in distribution grids located in open areas and territories with high soil resistivity.

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