Resetting the ground fault relay on a 28 MVA power transformer due to grounding method retrofit

• Main Authors: Hamzah, Eteruddin, Arlenny, -, Hadiana, Siswanto, Yanuar Z., Arief, Fathimah, Hasanti
• Format: Proceeding
• Language: English
• Published: IOP Publishing 2022
• Online Access: http://ir.unimas.my/id/eprint/40381/1/Resetting%20the%20ground%20-%20Copy.pdf; http://ir.unimas.my/id/eprint/40381/; https://iopscience.iop.org/article/10.1088/1755-1315/1041/1/012021

. The goal of the retrofit at Zamrud substation is to transform a 28 MVA power transformer's neutral point grounding system from direct grounding to grounding using a 20 Ohm Neutral Grounding Resistor (NGR). The amount of short-circuit current produced will fluctuate with the installation of NGR. It is necessary to re-setting the Ground Fault Relay (GFR) on Zamrud substation. To estimate the value of the short-circuit current after installing the NGR, the impedance matrix approach is used to calculate it. According to the results, LG's largest short-circuit current is 397.83 A and its smallest is 313.55 A. Meanwhile LLG has a maximum short-circuit current of 5.334.30 A and a minimum short-circuit current of 943.31 A. Therefore, after NGR installation, the value of the relay setting is as follows: GFR pickup current on the transformer grounding GFR relay is 234.29 A, GFR pickup current on the neutral feeder 1 is 19.96 A, GFR pickup current on the neutral feeder 2 is 30.42 A, and GFR pickup current on the neutral feeder 3 is 38.40 A.