Lightning protection system for high voltage transmission line in area with high grounding resistance

Abstract

Most disturbance on High Voltage Transmission Line (HVTL) caused by direct lightning strikes that can hit transmission tower or earth wire and produce back flashover (BFO) on insulators at the tower. Direct lightning strike to the phase wire produce travelling wave that will damage also the insulators and it's called Sheilding Failures (SF). These disturbances take place more often in the tropical area and have high tower grounding resistance. Appropriate lightning protection systems and grounding can minimize the damage caused by the strike. To solve the problem some of innovation technology have already installed and gave a significant result, such as Extended mast terminal [1]. Hight voltage 70 kV transmission line in Kupang area at east side of Indonesia suffer of disturbance due to lightning strikes. The existing protection by using additional grounded earth wire isolated by a 20 kV insulators installed at the top of the tower and connected to ground give no improvement to the protection system. With high ground resistance of the existing soil condition the disturbance is getting worse. Analysis on this sytem is carried out and improvement can be taken by using the EMT technology and the use of enhancement grounding cement.