power system analysis - symmetrical fault

3. Three identical generators are linked to a set of 66k V busbar through 11/66k V transformer as illustrated in Fig.2. Calculate reactance of reactor (10MVA) in per unit so that a symmetrical fault at point F will not exceed 250MVA. Use 50MVA as base value. 50MVA N 0.2 p.u 60MVA 10MVA 10MVA 0.12 p.u