System pentanahan (grounding) merupakan komponen proteksi dalam jaringan transmisi tegangan tinggi, karena berperan dalam menjaga keamanan jaringan akibat sambaran petir. Akibat ganguan petir dengan arus puncak sambaran sebesar -71 kA berdasarkan data Lightning Detection System (LDS) pada 28,29,30,32 SUTT 70 kV Kedung Badak− Kracak yang terjadi pada tanggal 24 November 2024, ditemukan anomali pada ke empat tersebut, anomali yang ada pada ke empat tersebut ditemukannya flash pada isolator fasa R, S, T dan hasil nilai tahanan pentanahan yang buruk melebihi Standar Pelayanan Listrik Nasional (SPLN) T5.012, 2020 yaitu < 10 Ω pasca gangguan. Tindak lanjut dari hasil temuan dilapangan dilakukan analisis dampak apa yang dapat merusak peralatan pada serta pencegahan system proteksi pada agar tetap handal apabila terjadi gangguan akibat petir. Analisis yang digunakan dalam kasus sambaran petir pada ada dua, yang pertama mencari nilai Back Flashover (BFO) dan yang kedua mencari nilai Shielding Failures (SF) kedua hal ini adalah ancaman utama pada akibat sambaran petir. Hasil analisis perhitungan BFO pada 28,29,30 hasilnya nilai BFO > BIL isolator SUTT 70kV dan nilai Shielding Failures (SF) masih dalam katagori standar 11.59° ≤ 15°. Dari permasalahan ini penulis melakukan penlitian untuk menurunkan nilai BFO apabila terjadi sambaran petir di Saluran Udara Tegangan Tinggi (SUTT) 70 kV. Implementasi pada system grounding di SUTT 70 kV dengan menerapkan metode Multi Direct Grounding (MDG). Metode MDG ini dapat menurunkan nilai BFO yang lebih besar dari Basic Isulation Level (BIL) isolator pada. Implementasi MDG dilakukan dengan menambahan titik pentanahan dari Ground Steel Wire (GSW) langsung ke tanah tanpa melewati sebagai media isolasinya untuk menurunkan impedansi total system. Hasil studi menunjukkan penggunaan MDG secara signifikan dapat menurunkan nilai BFO hingga lebih kecil dari BIL isolator sesuai dengan standar SPLN. Dengan demikian, implementasi MDG terbukti efektif dalam meningkatkan performa system pentanahan di jalur transmisi 70 kV Kedung Badak− Kracak.

The grounding system is a protection component in a high voltage transmission network, because it plays a role in maintaining network security due to lightning strikes. Due to lightning disturbances with a peak current of -71 kA based on LDS data on towers 28,29,30,32 SUTT 70 kV Kedung Badak - Kracak which occurred on November 24, 2024, anomalies were found in the four towers, the anomalies in the four towers were found to be flashes on the R, S, T phase insulators and the results of poor grounding resistance values exceeding the SPLN T5.012, 2020 standard, which is <10Ω after the disturbance. Follow-up to the findings in the field was carried out an analysis of what impacts could damage the equipment on the tower as well as prevention of the protection system on the tower so that it remains reliable in the event of disturbances due to lightning. There are two analyses used in cases of lightning strikes on towers, the first is to look for the Back Flashover (BFO) value and the second is to look for the Shielding Failures (SF) value. These two things are the main threats to towers due to lightning strikes. The results of the Back Flashover (BFO) calculation analysis on towers 28, 29, 30 show that the BFO value is > BIL of the 70kV SUTT tower insulator and the Shielding Failures (SF) value is still in the standard category of 11.59° ≤ 15°. From this problem, the author conducted a study to reduce the BFO value if a lightning strike occurs on the 70 kV SUTT tower. Implementation of the grounding system on the 70 kV SUTT tower by applying the Multi Direct Grounding (MDG) method. This MDG method can reduce the BFO value which is greater than the Basil Insulation Level (BIL) of the insulator on the tower. MDG implementation is carried out by adding a grounding point from the Ground Steel Wire (GSW) tower directly to the ground without passing through the tower as an isolation medium to reduce the total impedance of the system. The study results show that the use of MDG can significantly reduce the BFO value to less than the BIL of the tower insulator, as per the SPLN standard. Therefore, the implementation of MDG has proven effective in improving the performance of the grounding system on the 70 kV Kedung Badak-Kracak transmission line.