@thesis{thesis,
		author={Satya Dini  Hasna and Sirait  Deviana Fransiska},
		title ={EVALUASI SISTEM KOORDINASI PROTEKSI UTAMA DAN
PROTEKSI CADANGAN PADA TRAFO DAYA 60 MVA DI GI
PEMATANG SIANTAR},
		year={2023},
		url={http://156.67.221.169/5968/},
		abstract={Power transformers are the main components that are very important in the
transmission system, so they must have protection from interference that can reduce
transformer performance. The differential relay is the main protection in power
transformers. Differential relays work by comparing the incoming current in the relay
with the outgoing current in the relay. The relay detects interference and instructs a
circuit breaker (CB) for the trip. The purpose of this study is to evaluate the differential
relay protection system on a 60 MVA transformer when internal and external
interference occurs to find out whether the relay is working in accordance with
exsisting needs or needs to be resetting. The method used is by collecting the necessary
data at a 150 kV substation which is then processed by mathematical calculations or
manually and by simulating the work of differential relays using ETAP software. The
result of the mathematical calculation is that the differential current setting value is
0.1 A. The results of the simulation of the differential relay work system using ETAP
software, in internal interference show that the differential relay works at 0 ms and CB1
and CB2 work at 55 ms and 70 ms, while when there is an external disturbance the
differential relay does not work but what works is the feeder side OCR relay detects a
fault current (If) of 8347 kA at the time 2000 ms, therefore when the OCR relay will
order the PMT to trip with a time of 70 ms.}
		}