The distribution system indicated below is to be protected with overcurrent protection. Identify the locations where essentially directional overcurrent relays will be required considering proper fault discrimination. [Figure description: A single-line diagram. Bus-1 (left, fed by a Grid) connects through breaker Br-1 along a horizontal line to breaker Br-2 which connects to Bus-2 (centre). From Bus-2 another breaker Br-3 continues along the line to breaker Br-4 and Bus-3 (right, fed by another Grid). From Bus-2 a feeder goes down through breaker Br-6 and then through breaker Br-7 to Bus-4 (fed by a third Grid). Also from Bus-2, breaker Br-5 feeds a Load. So there are three grid sources (at Bus-1, Bus-3 and Bus-4) and one load fed via Br-5.]
- A. Br-1, Br-4, Br-8 and Br-7
- B. Br-2, Br-3, Br-5 and Br-6
- C. Br-2, Br-3 and Br-6
- D. Br-1, Br-4, Br-7, Br-5
Answer: C. Br-2, Br-3 and Br-6
Explanation: Breakers Br-2, Br-3, and Br-6 feed directly into Bus-2 from parallel tie lines/grid sources; they require directional overcurrent relays pointing into their respective lines to discriminate internal from external faults.