@thesis{thesis, author={Hadi Byanta Dhaniswara and Hariyanto Agung}, title ={ANALISIS SETTING RELE DIFERENSIAL PADA TRANSFORMATOR PLTU UNIT 3 DI PT. PJB UP GRESIK}, year={2018}, url={http://156.67.221.169/716/}, abstract={Protection on the transformer is a form of protection against the transformer to avoid damage to the equipment and also so that the stability of power distribution is maintained. Steam power plant at PT. PJB UP Gresik which has a total power amounting to 2255 MW, use some protection system in every equipment of its generation. One of the protection system contained in the PLTU transformer power plant unit 3, which has a capacity of 240 MVA for the primary/secondary voltage, has several relays coordinated in such a way as to secure the transformer. All the relays contained in the protection system transformer, there is a relay that workds not affected the setting of the coordination between the relay of the other, namely differential relay. This relay is used as the primary security in the transformer so that if interference occurs on the transformer, this relay will directly work quickly and accurately without any time delay to other relay works. The working principle of differential relay this is to compare the current secondary entry of the primary CT to secondary CT must be equal to zero. But in reality, there are several factors that effect the accuracy of the differential relay in this work, namely the error mismatch. Error mismatch obtained by 1,98%, which can be tolerated with a maximum error of mismatch by 4% which is the standard of the PLN. And the relay setting is obtained by 0,94 A which is assumed to be 0,3 A or 30% because the standard of PLN} }