OK,
Here is the outage from a Liney's point of view.
Take what you like from this, but hold me to nothing!.
One Generator(alternator), goes out on over-current trip, because it cannot supply the Grid with the required current base, this could be 5000-8000A at a voltage of 60kV(over here it is 11kV).
OK, Station A goes off line, due to an over current trip, the rest of the Grid has to make up for the loss in Generation capacity, meaning that Stations B,C,D and E have to carry the load of Station A, too.
This is just not possible, meaning that Stations B,C,D and E, will eventually trip out through over-current, hence the Black-out effect.
Anyone want to question this?, go right ahead!.