Wahani, Mikhael Richardo and Patras, Lily S. and Tulung, Novi M.
(2025)
Analisis Kegagalan Netral Grounding Resistor Pada Transformator Daya Di PLTD.
Fakultas Teknik Unsrat.
Abstract
Neutral Grounding Resistor (NGR) is one of the
important components in the transformer protection system in
Diesel Power Plants (PLTD), especially in maintaining system
stability when a ground fault occurs. This study analyzes the
causes of NGR failure in Laiwui PLTD which resulted in a
blackout for more than 12 hours on Obi Island. Based on the
results of technical calculations, it is known that the fault
current exceeded the NGR design capacity of 300 A, with an
actual current value reaching 442 A and heat energy of 54.5
MJ. The conductor temperature increased to 2000°C, causing
the cable to burn and the grounding system to fail. In addition,
the NGR resistance value decreased from 39.8 Ω to 27.9 Ω,
indicating internal degradation. Calculations of single-phase
to ground fault current, capacitive current, and transformer
impedance support the conclusion that the combination of
current surges, resistance degradation, and cable durability
mismatches are the main factors in system failure. These
results are expected to be a reference in improving the
reliability of protection systems in similar installations.
Keywords: Neutral Grounding Resistor, fault current,
PLTD, system failure, protection reliability.
Abstrak — Neutral Grounding Resistor (NGR)
merupakan salah satu komponen penting dalam sistem
proteksi transformator di Pembangkit Listrik Tenaga Diesel
(PLTD), khususnya dalam menjaga kestabilan sistem saat
terjadi gangguan hubung tanah. Penelitian ini menganalisis
penyebab kegagalan NGR pada PLTD Laiwui yang
mengakibatkan blackout selama lebih dari 12 jam di Pulau
Obi. Berdasarkan hasil perhitungan teknis, diketahui bahwa
arus gangguan melebihi kapasitas desain NGR sebesar 300
A, dengan nilai arus aktual mencapai 442 A dan energi panas
sebesar 54,5 MJ. Suhu konduktor meningkat hingga 2000°C,
menyebabkan kabel terbakar dan sistem pentanahan gagal
berfungsi. Selain itu, nilai tahanan NGR menurun dari 39,8
Ω menjadi 27,9 Ω, menunjukkan adanya degradasi internal.
Perhitungan arus gangguan satu fasa ke tanah, arus
kapasitif, dan impedansi trafo mendukung kesimpulan
bahwa kombinasi lonjakan arus, penurunan tahanan, dan
ketidaksesuaian daya tahan kabel menjadi faktor utama
kegagalan sistem. Hasil ini diharapkan dapat menjadi acuan
dalam peningkatan keandalan sistem proteksi di instalasi
sejenis.
Kata kunci : Neutral Grounding Resistor, arus gangguan,
PLTD, kegagalan sistem, keandalan proteksi.
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