The need for electrical energy nowadays increases as the growth of population, economy and industry. It should be supported by a reliable and continuous distribution system of human resources. Therefore, it is required an electric power system that has quality in accordance with the standards set by PT. PLN. This research aims to know the distribution of 20 kV system in every feeder at PT. PLN (Persero) Rayon Sedayu using SAIFI, SAIDI, ENS and AENS calculation index based on the monitoring data of power outage that has been occurring since 2017. Results obtained by the distribution system of Rayon Sedayu in 2017 if it is evaluated by SPLN 68-2 1986 standard is the values of SAIFI and SAIDI are two non-standard feeders, those are GDN 01 and GDN 04 feeder, while the other connection has met the standard. Beside that, when it is evaluated by IEEE std 1366-2003 standard, the values of SAIFI and SAIDI are four non-standard out of seven Rayon Sedayu feeders. Those are GDN 01, GDN 03, GDN 04 and GDN 05 feeder. If it is evaluated by ENS and AENS calculations, there will be an energy loss in every Rayo Sedayu feeders that are not channeled due to the power outages in the distribution network.