A lightning/surge arrester is a device used to limit the over voltages that may occur across transformers and other electrical apparatus due to lightning or switching surges. A lightning arrester may be a spark gap or may have a block of a semiconducting material such as zinc oxide. Lightning Arresters act as non linear resistors: - Low resistance during surges, so that overvoltages are limited - High resistance during normal operation to avoid negative effects on the power system Routine Testing carried out on Lightning Arresters: 1) Insulation Resistance (IR) Test 2) Thermo Vision Scanning 3) Leakage Current Measurement ----------------------------------------------------------------- Recommended Videos: Power Transformer Nameplate Details Explained in Hindi : https://youtu.be/6HrTgIOZC5k Difference between Metering CT & Protection CT : https://youtu.be/VSwLHAZLj6Y Tan Delta testing of CT: https://youtu.be/iFWFyM3rhuo Nameplate details of Current Transformer: https://youtu.be/eznFythQz3c Testing of Various Substation Equipments: https://www.youtube.com/playlist?list=PLohZ_Ucl1PNpWcwScyH2STs-vNvyOJt5N Testing of Lightning Arresters/Surge Arresters: https://youtu.be/AKJeiRaWGuY --------------------------------------------------------------------------