Analisa Tahanan Isolasi pada Transformator di Gardu Induk 150 KV Jekulo

Abstract A power transformer is an electrical power system equipment that is used to transform from high voltage to low voltage. One part of the transformer is insulation. Over time the transformer must be tested, namely insulation testing in order to reduce the operation failure on the transformer. The insulation test consists of calculating the polarization index to ensure the equipment is feasible to operate. Testing the polarization index is comparing the results of the prisoner after testing the voltage for 10 minutes with the detainee at the first minute, calculating the delta tangent to determine the quality of insulation of an electrical equipment, and to test the oil to find out whether the oil is still good or not. The results of testing at the 150 kV Jekulo substation on the polarization index data have an average of 1.25 - 2.0, which is still in good condition, tan delta testing is also still in a good condition below 0.5%, while for oil testing the transformer has an average of 78 , 3 kV which is still in good condition and in oil OLTC (On Load Tap Changer) has an average of 80.1 kV which is still in good condition. In transformer oil, if it is not good, filtering must be done or it must be replaced, while oil if brown or cloudy indicates oil must be replaced