Evaluate Lightning Protection Zone of DC Electric Railway at Solo - Yogyakarta Track Using Rolling Sphere Method

The overhead electrical line for electric train between Solo - Yogyakarta route worked at 1500 volts DC voltage. The intensity of lightning strikes in the region is relatively high. Especially in Brambanan Segment has a fault density of 1.8 to 2.37 events/km²/month, This network construction has lightning strike map over than 60,000 Cloud to Ground (CG) strikes. Lightning strikes striking the railway power transmission network have the potential to disrupt the train operations. This research was conducted to calculate the lightning strike current and evaluate the lightning protection zone. The lightning protection zone is determined using the rolling sphere method according to the IEC/EN 62305–3 standard. The protection area can be found by simulating the rolling sphere to the v-trust beam and cantilever structure with a certain radius touching the ground and ground wire. After evaluation, the maximum lightning peak current value is 40.125 kA with a rolling sphere radius of 88.17 m, yet this lightning strike has not been covered in the four lightning protection levels. The minimum lightning peak current value is 5 kA with a rolling sphere radius of 34.43 m and it is covered in level III lightning protection level. In general, the lightning arrester and overhead grounding wire (OHGW) installed in the v-trust beam and cantilever construction of overhead electrical line are protected by direct average lightning strikes.