@thesis{thesis, author={Budi S Purnomo Willy and MALIK DEDE SAEPUL}, title ={Kajian Penyetelan Rele Diferensial 87GT Pada Generator-Tranformator Unit 1 PLTP Gunung Salak PT. Indonesia Power UPJP Kamojang}, year={2019}, url={http://156.67.221.169/1622/}, abstract={Power plant has several components, one of which arre generator and transformers which are vital equipment in a power plant. In operating condition, generator and transformers can have short circuit fault which can cause electricity services to be disrupted. This short circuit fault can be overcome with differential relay. The differential relay works only if the differential current is greater or equal than setting current. This relay works comparing the incoming current and outgoing current. The calculated components are current transformer (CT) ratio, mismatch error and other parameters during normal condition and then calculate the value of relay parameter when its fault. The CT ratio installed to 150 kV generator-transformers side is 500:5 with consideration of the calculating of rating current is 269.37 A and on 11.8 kV side is 4000:5 A. Setting current (Iset) obtained from the calclutaion was 1.56 A and differential current (Id) was 1.59 A and the result of 3 phase short circuit fault current on secondary CT was 6.5 A.} }