6. Consider the customer end substation given in Fig. 26. For the metallic single-line-to-ground (SLG) fault at bus 3, i

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6 Consider The Customer End Substation Given In Fig 26 For The Metallic Single Line To Ground Slg Fault At Bus 3 I 1 (112.37 KiB) Viewed 50 times

6. Consider the customer end substation given in Fig. 26. For the metallic single-line-to-ground (SLG) fault at bus 3, it is required to calculate the fault current and bus 3 voltage. (a) Draw the equivalent positive, negative and zero sequence networks. (7 marks) (b) Establish the sequence network connection for SLG fault at bus 3; calculate the fault current (IF) and bus 3 voltage (V3) in phase (abc) quantities. (8 marks) (c) Find the required size of grounding reactor (in (2) for the transformer T1 to be inserted between its neutral and the ground to limit the fault current to 1000A. (5 marks) In your calculations, Ignore the resistance of the system components, Ignore the nonrotating loads, Assume 1 pu prefault voltage, Neglect the prefault currents, - Use 5 MVA power base. G 220 kV X1 = 96.8 X0 = 242 2 *** 6.3 kV, 5 MVA, 0.85 pf generator X1 (Xd') = 24% Xn X2 = 19% X0 = 9% Xn = 1.35 Utility 1 2 A 220 kV/ 34.5 kV 10 MVA X = 8% Hi T1 6.3 kV/ 34.5 kV T25 MVA X = 6% to T 3 Fault Nonrotating Loads