Kelayakan Current Transformer (CT) Pada Gardu Induk 150 kV Cilegon Baru ULTG Cilegon

Abstract

This study aimed to analyze the operational feasibility of the Current Transformer (CT) at the 150 kV Cilegon Baru Substation of PT. PLN (Persero). Current transformers play a vital role in protection and measurement systems, where insulation failure can cause fatal disruptions to power distribution. The research methods used included insulation resistance testing, grounding resistance testing, and tangent delta (tan delta) testing on phases R, S, and T. Voltage injection tests were conducted with variations from 500 V to 5 kV to measure current leakage. The results showed that the insulation resistance values on the primary-ground, secondary-ground, and inter-winding sides exceeded the minimum standard of 1000 MΩ, indicating excellent insulation conditions. The measured grounding resistance was below 1 Ω, meeting safety standards for personnel and equipment. Furthermore, the tangent delta testing yielded values of 0.30% (Phase R), 0.31% (Phase S), and 0.32% (Phase T). Since all tan delta values were below the threshold of 1%, it was concluded that the current transformer was in feasible operating condition and had not experienced dielectric degradation.

Abstrak

Penelitian ini bertujuan untuk menganalisis kelayakan operasional Transformator Arus (CT) pada Gardu Induk 150 kV Cilegon Baru PT. PLN (Persero). Transformator arus memiliki peran vital dalam sistem proteksi dan pengukuran, di mana kegagalan isolasi dapat menyebabkan gangguan fatal pada penyaluran tenaga listrik. Metode penelitian yang digunakan meliputi pengujian tahanan isolasi, tahanan pentanahan, dan pengujian tangen delta (tan delta) pada fasa R, S, dan T. Pengujian injeksi tegangan dilakukan dengan variasi 500 V hingga 5 kV untuk mengukur kebocoran arus. Hasil pengujian menunjukkan bahwa nilai tahanan isolasi pada sisi primer-tanah, sekunder-tanah, dan antar belitan melebihi standar minimum 1000 MΩ, yang mengindikasikan kondisi isolasi sangat baik. Nilai tahanan pentanahan terukur di bawah 1 Ω, memenuhi standar keamanan personil dan peralatan. Selanjutnya, pengujian tangen delta menghasilkan nilai 0,30% (Fasa R), 0,31% (Fasa S), dan 0,32% (Fasa T). Karena seluruh nilai tan delta berada di bawah batas ambang 1%, disimpulkan bahwa transformator arus dalam kondisi layak operasi dan tidak mengalami degradasi dielektrik.