A substation is quiet until it is not. The things that break are slow: gas leaking past a seal, a cooling group losing flow, an arrester ageing. All three are measured continuously and all three are usually found by a person on a round, at whatever interval the rounds happen to be.
The data problem here is sharper than in a works. An RTU point is AI:1043 and nothing else: no name, no unit, no equipment. An IEC 61850 tag has the meaning buried in a logical node. The station SCADA uses a mnemonic cut to seven characters. Three systems, three ideas of what a tag is, and the drawings that reconcile them are in a cabinet.
Indices are handed out in blocks, one block per bay, so a number that falls inside a block belongs to that bay. That is what an engineer does with the drawings on the table, and it is what the compiler does in a few milliseconds. On our substation it places the great majority and refuses the rest with a reason, which is the list you work through in week one.