@thesis{thesis, author={Koerniawan Tony and Rahmadani Safira Salma}, title ={PEMASANGAN AUTOMATIC CHANGE OVER (ACO) UNTUK MENINGKATKAN KEANDALAN PADA PELANGGAN PREMIUM TEGANGAN MENENGAH DIGARDU CP255}, year={2019}, url={http://156.67.221.169/1814/}, abstract={ACO cubicles are cubicles which have two different sources that can work automatically to move to a backup source in the event of a breakdown/voltage loss of one source. The two voltage source parallel system uses a medium voltage cubicle called Automatic Change Over (ACO). Increasing demand for electricity every time, this is because the number of customers continues to grow every year, so that if there is a power outage will cause losses. The loss can be calculated by calculating ENS (Energy Not Supplied). The use of ACO cubicles can improve the reliability of the electricity supply network, the reliability of the network in question is to keep electricity from going out to premium customers, the indices that show the reliability of the distribution system are SAIDI and SAIFI. the smaller the value of the two indexes, the more reliable the network system. The premium customers of Yayasan Kharisma Bangsa Gardu CP255 are supplied by 2 feeders, Pakde feeders and Friend feeders at the Gandul substation. Before using ACO energy that is not channeled is 1,367,887.99 kWh whereas after using ACO 63,74 kWh. Length of outage before using ACO SAIDI value 318 minutes/customer, after using ACO SAIDI value 0.9 seconds/customer.} }