Analisis Hasil Pengujian Tahanan Isolasi Transformator Daya Berdasarkan Hasil Uji Indeks Polarisasi, Tangen Delta, Rasio Tegangan, BDV(Break Down Voltage)

Power transformer is main equipment in electric power systems that connect directly with electrical transmission and distribution systems. One of the most important parts of a power transformer is isolation system. As the age and operation of the insulation conditions can worsening which can cause operational failure and damage to the transformer. The purpose of this research is knowing the quality condition of insulation resistance in the power transformer. Method used in this study the form of literature study by the author to deepen the material related to the title of research and data retrieval in the Main Substation Wonosari and Substation Sragen. The Data taken in form of polarization index test results, voltage ratio, tangent delta, and testing of oil breakdown voltage. After the data collected, then done the calculation and analyzed to get better results. Test results at the Wonosari Mainstay shows the value of polarization index on the ground-primary deterioration of 0,95. The result voltage of ratio test shows good condition with average value below 0,5%. The result of tangent delta test indicates the occurrence of worsening in CL mode 0,83- 1,65%. Average oil test results show good condition that is oil bottom 64,5kV and oil oltc 54,4kV. The results of the test at the Sragen Substation shows the value of the polarization index still good average value above 1,1-1,25. The result of voltage ratio test shows good condition with average value below 0,5%. The result of delta tangent test shows the decrease of negative delta tan in mode (UST) that is equal to -0.12% and slightly worsening in CL mode by 0,55%. Average oil test results show good condition that is oil bottom 86,4kV and oil oltc 85,2k