Overcurrent and Ground Fault Relay Protection Settings at Tranformator-1 150kV/20kV Braga Substation


  • Handoko Iskandar Universitas Jenderal Achmad Yani


DigSilent power factory 15.1, Braga substation, Ground Fault Relay, Over Current Relay.


The occurrence of malfunctions in the substation results in power outages and losses in the electrical energy distribution system to consumers. Many tests are carried out to see the performance of the protection system, including the parameters of the Over Current Relay (OCR) and Ground Fault Relay (GFR) on the electrical energy distribution system. This study uses several test parameters including setting current, pick-up, drop-off, ratio, characteristics and instantaneous working time. Afterward, we simulate using DigSilent Power Factory 15.1 software based on existing equipment specification data of Braga Substation. The results show an OCR accuracy rate of 94.4% on the 20kV side and 94.6% on the 150kV side. Meanwhile, the GFR for the 20kV side is 92.39% and the 150kV side is 94.87%. The OCR setting value for the 20kV side is 5.2A with a pick-up current of 5.23A and a drop-off current of 4.939 while on the 150kV side it is 0.93A with a pick-up current of 0.93A and a drop-off current of 0.88A. The GFR setting value on the 20kV side is 0.9A with a pick-up current of 0.92A and a drop-off current of 0.85A while on the 150kV side it is 0.39A with a pick-up current of 0.39A and a drop-up current of 0.37A. The setting value on the 20kV side is greater than on the 150kV side due to the difference in the Current Transformer ratio value. The simulation results reveal that the OCR and GFR characteristic curves on both sides match the criteria for a high-performance protection system.



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