Power system fault analysis
You are giving incomplete info, which makes it difficult to give clear help. That is probably from a test or assignment as just pasting here the end of the question makes it harder than it should be. Just asking straight up where is the fault makes no sense if you don't get told what protection triggered or other info.

that aside, the basic method.

just assume the fault happens at each node, and compare the current that flows through each protection device and see what would trip first.

this is just an example, Imagine the fault is 1000 Amperes(it isn't, you need to calculate on your own)

Now go to every element see at 1000 Amperes and find out what triggers first, so depending on what triggered you can figure out what protection will trip.

if you go to a different location, the current will be different and the protections involved will be different so every case does not give the same answer, I believe you were told earlier in the problem what tripped or something of the like.