ConstructionofcoalhandlingfacilityPTXdemandingtheneedforan analysisofthe equipmentratingcircuitbreaker(CircuitBreaker),sothatthe CircuitBreaker(CB)can secure thepowersystemagainstharmfulinterference,especiallyinterference symmetrical short-circuitthree-phase.Foritwas doneastudyofshortcircuitintheelectricpower system.Calculationofthesymmetricalshort-circuitfaultcurrentis basedonsoftware simulationETAP 12.6. The conclusionisthatthe biggestfaultcurrent. The results obtainedforsymmetricalthree-phasedisorders,thegreatestdisruptionoccursinLV MCCbus(400V) withinitialsymmetricalfaultcurrent(I "k) amountedto62.170kA,the maximum short circuit current (Ip)of 130.450 kA. Keywords: power systemanalysis, 3-phaseshortcircuit, ETAP.