T his substation is a power plant outlet for Muara Karang Lama PLTU. This substation with a one and a half breaker type has 12 diameters consisting of 8 AIS (Air Insulated Switchyard) diameters and 4 GIS (Gas Insulated Switchyard) diameters. The research entitled "Line Current Differential Relay Analysis Study on the SKTT 150KV Angke Line at Muara Karang Lama Substation", has formulated the problem of how reliable the line current differential relay is and what causes disruption to the SKTT 150KV Angke - Muara Karang Lama transmission line. The disturbance that occurs is caused by the application of inappropriate relay settings which can cause work errors in the relay, so that the Ic Compensat parameter is not activated which causes an increase in Idiff current, so the value is not selective when load fluctuations occur. The purpose of this study is to determine the disturbance that occurs in the protection, determine the relay setting current, and determine the calculation results of the relay settings. This research can use the method of field studies and literature. The data obtained are line current differential relay conductor data, cable technical data, and interference data and a single line diagram is obtained on the Angke-Muara Karang Lama SKTT 150KV transmission line. The data obtained were analyzed using Mathcad software. Then the simulation results are obtained where the first simulation is the calculation of the differential current on the line current differential relay, it is found that the setting at the beginning of the application is that the Ic Compensat setting (C1 and C0) has not been activated, causing interference with the transmission of SKTT 150KV Angke - Muara Karang Lama, which second is for the calculation of Ic Compensate the value is 0.47μF, the calculation for Is1 and Is2 is obtained 0.2 and the calculation for k1 is obtained 30% while k2 is obtained by 150% (k1 and k2 are in accordance with the value of the manufacture).