ANALISIS RELE ARUS BERLEBIH (OVER CURRENT RELAY ) PADA TRANSFORMATOR DI PT. PLN GARDU INDUK 150 KV BANTUL

The distribution of electrical energy must meet the standards and get better, but there are various kinds of disturbances in the distribution. One of the disturbances in the substation is a short circuit, resulting in the interruption of the flow of electricity. One type is a 3-phase short-circuit fault which if it occurs will produce a very large current and can cause the transformer to burn out. Therefore, a protection system is needed to protect the disturbed area and reduce the damage by limiting the disturbed area. This study discusses the comparison of the 150 kV and 20 kV side OCR settings using manual calculations with field settings on the 3 transformers at the 150 kV Substation Bantul. The method used in this research is data collection at the 150 kV substation Bantul and interviews which are then followed by mathematical calculations and then simulated with ETAP 12.6. Comparison between setting in the field and setting the calculation results there is no significant difference, on the 150 kV side of transformer I the relay working time is 1.34 seconds while the field setting is 1.33 seconds has a difference of 0.01 seconds, for the 20 kV side the relay working time is 0.89 seconds while setting in the field of 0.815 seconds has a difference of 0.075 seconds. Transformers I, I has a primary I set of 277.2 A for the 150 kV side while for the 20 kV side the value is 2080.8 A then for the secondary I set the 150 kV side is 0.92 A and on the 20 kV side TF I is 5.2 A. the protection system is well coordinated and complies with IEC standards.