Two 13 kV, 50 MVA three-phase generators with a reactance of 0.4 pu per phase are connected to a busbar (referred to as

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Two 13 Kv 50 Mva Three Phase Generators With A Reactance Of 0 4 Pu Per Phase Are Connected To A Busbar Referred To As 1 (73.11 KiB) Viewed 24 times

Two 13 kV, 50 MVA three-phase generators with a reactance of 0.4 pu per phase are connected to a busbar (referred to as busbar A). Two identical generators are connected to a second busbar (referred to as busbar B). The two busbars are connected via a bus-section circuit breaker which is normally closed. A 300km long overhead three-phase radial feeder is supplied from busbar A via a 20MVA, 13kV/132kV three-phase step-up transformer with a reactance of 8% per phase. The reactance of the overhead line is 0.49 per phase per kilometre. All circuit resistances may be assumed negligible. a) Draw a one line diagram of the system described above. [6 marks] b) Using a common base of 50MVA, calculate the fault current that would result from a symmetrical three-phase short-circuit fault at the end of the overhead feeder. [10 marks] c) Calculate the fault level at busbar A. [4 marks] d) Calculate the required reactance of a reactor to connect busbar A to busbar B in order to limit the fault level at busbar A to 400 MVA. [10 marks]