QUESTION Question 4: (12 marks) Consider the single line diagram of a distribution network as given in Figure Q4. The maximum fault current in line BC is 3000 A and in line AB is 9000 A. Operation time for circuit breakers at Bus A and Bus B is 0.5 s. All relays are 1 A, normal inverse BS142 IDMT relays. Use the following general expression for the relays operating time: T KxTMS PSM-1 The available relay tap settings are : 2.5 A, 3.75 A, 5 A, 6.25 A, 7.5 A, 8.75 A and 10 A. The maximum load currents are as shown in Figure Q4. Design a suitable protection scheme for Feeder I as shown in Figure Q4. 11W ORV GRY 2-600 2-03-2 2-02 415V 415 V 415V R10 R12 R14 Bus AE RA Feeder 2 Feeder Feeder 4 Ferdir Feeder Fender 100 A Bus B RE LA Bus C Feeder