The post fault $22$ kV network is shown in Figure Q$2$a$.$ The network is only protected by overcurrent relay and the $8$ tripped breakers activated by overcurrent relays are shown in white rectangles in Figure Q$2$a$.$ The overcurrent relay settings for each feeder are shown in Table Q$2$a$,$ and the load at each node in Table Q$2$b$.$

Figure Q$2$a

Table Q$2$a Table Q$2$b

$($a$)$ Identify the possible fault location. Give reasons to support your fault diagnose inference.

$(10$ marks$)$

$($b$)$ The fault is subsequently cleared and supply has been all restored. However, on the next day, all breakers connected to Bus$1$ failed and cannot be closed as shown in Figure Q$2$b$.$ As a result the feeder from Bus$2$ to Bus$7$ tripped resulting in a loss of supply to Bus$1,$ Bus$3,$ Bus$4,$ Bus$7,$ Bus$9,$ Bus$10,$ Bus$13,$ Bus$15,$ Bus$16$ and Bus$17.$ List the appropriate switching steps so that supply to all nodes can be fully restored, or to as many nodes as possible. Determine the two highest$-$loading circuits in amperes and also nodes that supply cannot be restored if any.