Analisis Dampak Teknis Gangguan Hubung Singkat Terhadap Kinerja Jaringan Distribusi 20 kV di PT. PLN ULP Siantar

Abstract

Short-circuit faults are one of the main causes of reduced reliability in power distribution systems. This study analyses the characteristics of short-circuit currents in the 20 kV distribution network at PT PLN ULP Siantar using ETAP 12.6.0 software, covering symmetrical faults (three-phase) and asymmetrical faults (line-to-ground, line-line-to- ground, and line-to—line). Focus of this research is to determine the magnitude of fault currents and to evaluate the suitability of protection equipment ratings, namelyyy overcurrent relays (OCR) and circuit breakers (CB). Simulation results at 14 fault locations shot what the largest short-circuit current in the medium-voltage side occurs at MVCB A55 in feeder PT.07 with value of 4.21 kA, while in the low-voltage side it occurs at LVCB L2SISIP with value of 10.51 kA. Three-phase faults are used as the main reference in determining the breaking capacity of protection devices because they generate the highest current. All selected protection devices meet technical criteria with breaking capacities exceeding the fault current values. In addition, protection coordination demonstrates good selectivity, where the LVCB operates faster than the MVCB, allowing the system to isolate faults locally without affecting the entire network